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1.
Plant Cell Rep ; 43(6): 149, 2024 May 23.
Article in English | MEDLINE | ID: mdl-38780624

ABSTRACT

KEY MESSAGE: The small-molecule glucosyltransferase loss-of-function mutant ugt76b1 exhibits both SID2- or NPR1-dependent and independent facets of enhanced plant immunity, whereupon FMO1 is required for the SID2 and NPR1 independence. The small-molecule glucosyltransferase UGT76B1 inactivates salicylic acid (SA), isoleucic acid (ILA), and N-hydroxypipecolic acid (NHP). ugt76b1 loss-of-function plants manifest an enhanced defense status. Thus, we were interested how UGT76B1 genetically integrates in defense pathways and whether all impacts depend on SA and NHP. We study the integration of UGT76B1 by transcriptome analyses of ugt76b1. The comparison of transcripts altered by the loss of UGT76B1 with public transcriptome data reveals both SA-responsive, ISOCHORISMATE SYNTHASE 1/SALICYLIC ACID INDUCTION DEFICIENT 2 (ICS1/SID2)- and NON EXPRESSOR OF PR GENES 1 (NPR1)-dependent, consistent with the role of UGT76B1 in glucosylating SA, and SA-non-responsive, SID2/NPR1-independent genes. We also discovered that UGT76B1 impacts on a group of genes showing non-SA-responsiveness and regulation by infections independent from SID2/NPR1. Enhanced resistance of ugt76b1 against Pseudomonas syringae is partially independent from SID2 and NPR1. In contrast, the ugt76b1-activated resistance is completely dependent on FMO1 encoding the NHP-synthesizing FLAVIN-DEPENDENT MONOOXYGENASE 1). Moreover, FMO1 ranks top among the ugt76b1-induced SID2- and NPR1-independent pathogen responsive genes, suggesting that FMO1 determines the SID2- and NPR1-independent effect of ugt76b1. Furthermore, the genetic study revealed that FMO1, ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), SID2, and NPR1 are required for the SA-JA crosstalk and senescence development of ugt76b1, indicating that EDS1 and FMO1 have a similar effect like stress-induced SA biosynthesis (SID2) or the key SA signaling regulator NPR1. Thus, UGT76B1 influences both SID2/NPR1-dependent and independent plant immunity, and the SID2/NPR1 independence is relying on FMO1 and its product NHP, another substrate of UGT76B1.


Subject(s)
Arabidopsis Proteins , Arabidopsis , Gene Expression Regulation, Plant , Glucosyltransferases , Salicylic Acid , Salicylic Acid/metabolism , Arabidopsis Proteins/genetics , Arabidopsis Proteins/metabolism , Arabidopsis/genetics , Arabidopsis/microbiology , Arabidopsis/immunology , Arabidopsis/metabolism , Glucosyltransferases/genetics , Glucosyltransferases/metabolism , Plant Immunity/genetics , Pseudomonas syringae/pathogenicity , Pseudomonas syringae/physiology , Pipecolic Acids/metabolism , Plant Diseases/microbiology , Plant Diseases/genetics , Plant Diseases/immunology , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism
2.
J Chem Inf Model ; 64(9): 3933-3941, 2024 May 13.
Article in English | MEDLINE | ID: mdl-38666964

ABSTRACT

ß-Amyrin synthase (bAS) is a representative plant oxidosqualene cyclase (OSC), and previous studies have identified many functional residues and mutants that can alter its catalytic activity. However, the regulatory mechanism of the active site architecture for adjusting the catalytic activity remains unclear. In this study, we investigate the function of key residues and their regulatory effects on the catalytic activity of Glycyrrhiza glabra ß-amyrin synthase (GgbAS) through molecular dynamics simulations and site-directed mutagenesis experiments. We identified the plasticity residues located in two active site regions and explored the interactions between these residues and tetracyclic/pentacyclic intermediates. Based on computational and experimental results, we further categorize these plasticity residues into three types: effector, adjuster, and supporter residues, according to their functions in the catalytic process. This study provides valuable insights into the catalytic mechanism and active site plasticity of GgbAS, offering important references for the rational enzyme engineering of other OSC enzyme.


Subject(s)
Biocatalysis , Catalytic Domain , Intramolecular Transferases , Molecular Dynamics Simulation , Intramolecular Transferases/metabolism , Intramolecular Transferases/chemistry , Intramolecular Transferases/genetics , Mutagenesis, Site-Directed
3.
J Agric Food Chem ; 72(18): 10584-10595, 2024 May 08.
Article in English | MEDLINE | ID: mdl-38652774

ABSTRACT

Triterpenoids from Camellia species comprise a diverse class of bioactive compounds with great therapeutic potential. However, triterpene biosynthesis in tea plants (Camellia sinensis) remains elusive. Here, we identified eight putative 2,3-oxidosqualene cyclase (OSC) genes (CsOSC1-8) from the tea genome and characterized the functions of five through heterologous expression in yeast and tobacco and transient overexpression in tea plants. CsOSC1 was found to be a ß-amyrin synthase, whereas CsOSC4, 5, and 6 exhibited multifunctional α-amyrin synthase activity. Molecular docking and site-directed mutagenesis showed that the CsOSC6M259T/W260L double mutant yielded >40% lupeol, while the CsOSC1 W259L single mutant alone was sufficient for lupeol production. The V732F mutation in CsOSC5 altered product formation from friedelin to taraxasterol and ψ-taraxasterol. The L254 M mutation in the cycloartenol synthase CsOSC8 enhanced the catalytic activity. Our findings shed light on the molecular basis governing triterpene diversity in tea plants and offer potential avenues for OSC engineering.


Subject(s)
Camellia sinensis , Intramolecular Transferases , Plant Proteins , Triterpenes , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , Intramolecular Transferases/chemistry , Triterpenes/metabolism , Triterpenes/chemistry , Plant Proteins/genetics , Plant Proteins/metabolism , Plant Proteins/chemistry , Camellia sinensis/genetics , Camellia sinensis/enzymology , Camellia sinensis/metabolism , Camellia sinensis/chemistry , Molecular Docking Simulation , Genome, Plant
4.
Org Lett ; 26(15): 3119-3123, 2024 Apr 19.
Article in English | MEDLINE | ID: mdl-38588021

ABSTRACT

Six oxidosqualene cyclases (NiOSC1-NiOSC6) from Neoalsomitra integrifoliola were characterized for the biosynthesis of diverse triterpene scaffolds, including tetracyclic and pentacyclic triterpenes from the 2,3-oxidosqualene (1) and oxacyclic triterpenes from the 2,3:22,23-dioxidosqualene (2). NiOSC1 showed high efficiency in the production of naturally rare (20R)-epimers of oxacyclic triterpenes. Mutagenesis results revealed that the NiOSC1-F731G mutant significantly increased the yields of (20R)-epimers compared to the wild type. Homology modeling and molecular docking elucidated the origin of the (20R)-configuration in the epoxide addition step.


Subject(s)
Intramolecular Transferases , Squalene/analogs & derivatives , Triterpenes , Molecular Docking Simulation , Pentacyclic Triterpenes , Intramolecular Transferases/genetics
5.
J Nat Prod ; 87(4): 1036-1043, 2024 Apr 26.
Article in English | MEDLINE | ID: mdl-38600636

ABSTRACT

Triterpenoids are a type of specialized metabolites that exhibit a wide range of biological activities. However, the availability of some minor triterpenoids in nature is limited, which has hindered our understanding of their pharmacological potential. To overcome this limitation, heterologous biosynthesis of triterpenoids in yeast has emerged as a promising and time-efficient production platform for obtaining these minor compounds. In this study, we analyzed the transcriptomic data of Enkianthus chinensis to identify one oxidosqualene cyclase (EcOSC) gene and four CYP716s. Through heterologous expression of these genes in yeast, nine natural pentacyclic triterpenoids, including three skeleton products (1-3) produced by one multifunctional OSC and six minor oxidation products (4-9) catalyzed by CYP716s, were obtained. Of note, we discovered that CYP716E60 could oxidize ursane-type and oleanane-type triterpenoids to produce 6ß-OH derivatives, marking the first confirmed C-6ß hydroxylation in an ursuane-type triterpenoid. Compound 9 showed moderate inhibitory activity against NO production and dose-dependently reduced IL-1ß and IL-6 production at the transcriptional and protein levels. Compounds 1, 2, 8, and 9 exhibited moderate hepatoprotective activity with the survival rates of HepG2 cells from 61% to 68% at 10 µM.


Subject(s)
Anti-Inflammatory Agents , Cytochrome P-450 Enzyme System , Intramolecular Transferases , Triterpenes , Triterpenes/pharmacology , Triterpenes/chemistry , Humans , Cytochrome P-450 Enzyme System/metabolism , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/chemistry , Molecular Structure , Saccharomyces cerevisiae , Hydroxylation , Hep G2 Cells , Interleukin-1beta/metabolism , Interleukin-6/metabolism , Protective Agents/pharmacology , Protective Agents/chemistry
6.
RNA ; 30(5): 530-536, 2024 Apr 16.
Article in English | MEDLINE | ID: mdl-38531650

ABSTRACT

Pseudouridine is an abundant mRNA modification found in diverse organisms ranging from bacteria and viruses to multicellular plants and humans. New developments in pseudouridine profiling provide quantitative tools to map mRNA pseudouridylation sites. Sparse biochemical studies establish the potential for mRNA pseudouridylation to affect most stages of the mRNA life cycle from birth to death. This recent progress sets the stage for deeper investigations into the molecular and cellular functions of specific mRNA pseudouridines, including in disease.


Subject(s)
RNA, Messenger , Research , RNA, Messenger/chemistry , RNA, Messenger/metabolism , Intramolecular Transferases/metabolism , Transcription, Genetic , RNA Precursors/chemistry , RNA Precursors/metabolism , RNA-Binding Proteins/metabolism , Protein Biosynthesis , Protein Binding , Humans , Animals , Research/trends
7.
Biochemistry ; 63(7): 913-925, 2024 Apr 02.
Article in English | MEDLINE | ID: mdl-38471967

ABSTRACT

Several anaerobic bacterial species, including the Gram-negative oral bacterium Fusobacterium nucleatum, ferment lysine to produce butyrate, acetate, and ammonia. The second step of the metabolic pathway─isomerization of ß-l-lysine to erythro-3,5-diaminohexanoate─is catalyzed by the adenosylcobalamin (AdoCbl) and pyridoxal 5'-phosphate (PLP)-dependent enzyme, lysine 5,6-aminomutase (5,6-LAM). Similar to other AdoCbl-dependent enzymes, 5,6-LAM undergoes mechanism-based inactivation due to loss of the AdoCbl 5'-deoxyadenosyl moiety and oxidation of the cob(II)alamin intermediate to hydroxocob(III)alamin. Herein, we identified kamB and kamC, two genes responsible for ATP-dependent reactivation of 5,6-LAM. KamB and KamC, which are encoded upstream of the genes corresponding to α and ß subunits of 5,6-LAM (kamD and kamE), co-purified following coexpression of the genes in Escherichia coli. KamBC exhibited a basal level of ATP-hydrolyzing activity that was increased 35% in a reaction mixture that facilitated 5,6-LAM turnover with ß-l-lysine or d,l-lysine. Ultraviolet-visible (UV-vis) spectroscopic studies performed under anaerobic conditions revealed that KamBC in the presence of ATP/Mg2+ increased the steady-state concentration of the cob(II)alamin intermediate in the presence of excess ß-l-lysine. Using a coupled UV-visible spectroscopic assay, we show that KamBC is able to reactivate 5,6-LAM through exchange of the damaged hydroxocob(III)alamin for AdoCbl. KamBC is also specific for 5,6-LAM as it had no effect on the rate of substrate-induced inactivation of the homologue, ornithine 4,5-aminomutase. Based on sequence homology, KamBC is structurally distinct from previously characterized B12 chaperones and reactivases, and correspondingly adds to the list of proteins that have evolved to maintain the cellular activity of B12 enzymes.


Subject(s)
Intramolecular Transferases , Lysine , Lysine/metabolism , Intramolecular Transferases/metabolism , Cobamides/metabolism , Adenosine Triphosphate
8.
Mol Microbiol ; 121(5): 912-926, 2024 May.
Article in English | MEDLINE | ID: mdl-38400525

ABSTRACT

Fungal cell walls represent the frontline contact with the host and play a prime role in pathogenesis. While the roles of the cell wall polymers like chitin and branched ß-glucan are well understood in vegetative and pathogenic development, that of the most prominent galactose-containing polymers galactosaminogalactan and fungal-type galactomannan is unknown in plant pathogenic fungi. Mining the genome of the maize pathogen Colletotrichum graminicola identified the single-copy key galactose metabolism genes UGE1 and UGM1, encoding a UDP-glucose-4-epimerase and UDP-galactopyranose mutase, respectively. UGE1 is thought to be required for biosynthesis of both polymers, whereas UGM1 is specifically required for fungal-type galactomannan formation. Promoter:eGFP fusion strains revealed that both genes are expressed in vegetative and in pathogenic hyphae at all stages of pathogenesis. Targeted deletion of UGE1 and UGM1, and fluorescence-labeling of galactosaminogalactan and fungal-type galactomannan confirmed that Δuge1 mutants were unable to synthesize either of these polymers, and Δugm1 mutants did not exhibit fungal-type galactomannan. Appressoria of Δuge1, but not of Δugm1 mutants, were defective in adhesion, highlighting a function of galactosaminogalactan in the establishment of these infection cells on hydrophobic surfaces. Both Δuge1 and Δugm1 mutants showed cell wall defects in older vegetative hyphae and severely reduced appressorial penetration competence. On intact leaves of Zea mays, both mutants showed strongly reduced disease symptom severity, indicating that UGE1 and UGM1 represent novel virulence factors of C. graminicola.


Subject(s)
Cell Wall , Colletotrichum , Fungal Proteins , Galactose , Mannans , Plant Diseases , UDPglucose 4-Epimerase , Virulence Factors , Zea mays , Colletotrichum/genetics , Colletotrichum/metabolism , Colletotrichum/pathogenicity , Zea mays/microbiology , Galactose/metabolism , Galactose/analogs & derivatives , Plant Diseases/microbiology , Cell Wall/metabolism , Virulence Factors/genetics , Virulence Factors/metabolism , UDPglucose 4-Epimerase/metabolism , UDPglucose 4-Epimerase/genetics , Mannans/metabolism , Fungal Proteins/genetics , Fungal Proteins/metabolism , Galactans/metabolism , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , Hyphae/metabolism , Virulence/genetics
9.
Nucleic Acids Res ; 52(8): 4644-4658, 2024 May 08.
Article in English | MEDLINE | ID: mdl-38375885

ABSTRACT

Pseudouridine, one of the most abundant RNA modifications, is synthesized by stand-alone or RNA-guided pseudouridine synthases. Here, we comprehensively mapped pseudouridines in rRNAs, tRNAs and small RNAs in the archaeon Sulfolobus islandicus and identified Cbf5-associated H/ACA RNAs. Through genetic deletion and in vitro modification assays, we determined the responsible enzymes for these modifications. The pseudouridylation machinery in S. islandicus consists of the stand-alone enzymes aPus7 and aPus10, and six H/ACA RNA-guided enzymes that account for all identified pseudouridines. These H/ACA RNAs guide the modification of all eleven sites in rRNAs, two sites in tRNAs, and two sites in CRISPR RNAs. One H/ACA RNA shows exceptional versatility by targeting eight different sites. aPus7 and aPus10 are responsible for modifying positions 13, 54 and 55 in tRNAs. We identified four atypical H/ACA RNAs that lack the lower stem and the ACA motif and confirmed their function both in vivo and in vitro. Intriguingly, atypical H/ACA RNAs can be modified by Cbf5 in a guide-independent manner. Our data provide the first global view of pseudouridylation in archaea and reveal unexpected structures, substrates, and activities of archaeal H/ACA RNPs.


Subject(s)
Pseudouridine , RNA, Archaeal , RNA, Transfer , Sulfolobus , Pseudouridine/metabolism , Sulfolobus/genetics , Sulfolobus/metabolism , RNA, Transfer/metabolism , RNA, Transfer/genetics , RNA, Archaeal/genetics , RNA, Archaeal/metabolism , RNA, Archaeal/chemistry , RNA, Ribosomal/metabolism , RNA, Ribosomal/genetics , Archaeal Proteins/metabolism , Archaeal Proteins/genetics , RNA Processing, Post-Transcriptional , RNA, Guide, CRISPR-Cas Systems/genetics , RNA, Guide, CRISPR-Cas Systems/metabolism , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism
10.
Plant J ; 118(3): 731-752, 2024 May.
Article in English | MEDLINE | ID: mdl-38226777

ABSTRACT

Prunella vulgaris is one of the bestselling and widely used medicinal herbs. It is recorded as an ace medicine for cleansing and protecting the liver in Chinese Pharmacopoeia and has been used as the main constitutions of many herbal tea formulas in China for centuries. It is also a traditional folk medicine in Europe and other countries of Asia. Pentacyclic triterpenoids are a major class of bioactive compounds produced in P. vulgaris. However, their biosynthetic mechanism remains to be elucidated. Here, we report a chromosome-level reference genome of P. vulgaris using an approach combining Illumina, ONT, and Hi-C technologies. It is 671.95 Mb in size with a scaffold N50 of 49.10 Mb and a complete BUSCO of 98.45%. About 98.31% of the sequence was anchored into 14 pseudochromosomes. Comparative genome analysis revealed a recent WGD in P. vulgaris. Genome-wide analysis identified 35 932 protein-coding genes (PCGs), of which 59 encode enzymes involved in 2,3-oxidosqualene biosynthesis. In addition, 10 PvOSC, 358 PvCYP, and 177 PvUGT genes were identified, of which five PvOSCs, 25 PvCYPs, and 9 PvUGTs were predicted to be involved in the biosynthesis of pentacyclic triterpenoids. Biochemical activity assay of PvOSC2, PvOSC4, and PvOSC6 recombinant proteins showed that they were mixed amyrin synthase (MAS), lupeol synthase (LUS), and ß-amyrin synthase (BAS), respectively. The results provide a solid foundation for further elucidating the biosynthetic mechanism of pentacyclic triterpenoids in P. vulgaris.


Subject(s)
Chromosomes, Plant , Genome, Plant , Pentacyclic Triterpenes , Prunella , Prunella/genetics , Prunella/metabolism , Pentacyclic Triterpenes/metabolism , Genome, Plant/genetics , Chromosomes, Plant/genetics , Plant Proteins/genetics , Plant Proteins/metabolism , Phylogeny , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , Triterpenes/metabolism
11.
Int J Biol Macromol ; 259(Pt 2): 129369, 2024 Feb.
Article in English | MEDLINE | ID: mdl-38218271

ABSTRACT

The impact of the cell wall structure of Monascus purpureus M9 on the secretion of extracellular monascus pigments (exMPs) was investigated. To modify the cell wall structure, UDP-galactopyranose mutase (GlfA) was knocked out using Agrobacterium-mediated transformation method, leading to a significant reduction in the Galf-based polysaccharide within the cell wall. Changes in mycelium morphology, sporogenesis, and the expression of relevant genes in M9 were also observed following the mutation. Regarding MPs secretion, a notable increase was observed in six types of exMPs (R1, R2, Y1, Y2, O1 and O2). Specifically, these exMPs exhibited enhancement of 1.33, 1.59, 0.8, 2.45, 2.89 and 4.03 times, respectively, compared to the wild-type strain. These findings suggest that the alteration of the cell wall structure could selectively influence the secretion of MPs in M9. The underlying mechanisms were also discussed. This research contributes new insights into the regulation of the synthesis and secretion of MPs in Monascus spp..


Subject(s)
Galactose/analogs & derivatives , Intramolecular Transferases , Mannans , Monascus , Monascus/genetics , Monascus/metabolism , Pigments, Biological , Carbohydrate Metabolism , Fermentation
12.
Chemistry ; 30(23): e202304163, 2024 Apr 22.
Article in English | MEDLINE | ID: mdl-38258332

ABSTRACT

Ectoine synthase (EctC) catalyses the ultimate step of ectoine biosynthesis, a kosmotropic compound produced as compatible solute by many bacteria and some archaea or eukaryotes. EctC is an Fe2+-dependent homodimeric cytoplasmic protein. Using Mössbauer spectroscopy, molecular dynamics simulations and QM/MM calculations, we determined the most likely coordination number and geometry of the Fe2+ ion and proposed a mechanism of the EctC-catalysed reaction. Most notably, we show that apart from the three amino acids binding to the iron ion (Glu57, Tyr84 and His92), one water molecule and one hydroxide ion are required as additional ligands for the reaction to occur. They fill the first coordination sphere of the Fe2+-cofactor and act as critical proton donors and acceptors during the cyclization reaction.


Subject(s)
Amino Acids, Diamino , Hydro-Lyases , Iron , Molecular Dynamics Simulation , Amino Acids, Diamino/chemistry , Amino Acids, Diamino/metabolism , Iron/chemistry , Iron/metabolism , Intramolecular Transferases/metabolism , Intramolecular Transferases/chemistry , Biocatalysis , Bacteria/enzymology , Catalysis , Cyclization , Ligands , Water/chemistry
13.
Gene ; 894: 147971, 2024 Feb 05.
Article in English | MEDLINE | ID: mdl-37949417

ABSTRACT

Saponins derived from holothurians have high potential medicinal value. However, the de novo synthesis of the derivatization of triterpenes is still unclear. Oxidative squalene cyclase (OSC) can catalyze 2,3-Oxidosqualene into diverse products that serve as important precursors for triterpene synthesis. However, the function of theOSCgene in Chiridotasp. hasnot been elucidated. In this study, an OSCgenederived from the deep-sea holothurianChiridota sp. was cloned and characterized functionally in a yeast system. The open reading frame of the OSC gene was 2086 bp, which encoded 695 amino acids. The Chiridota sp. OSC gene has a similarity of 66.89 % to the OSC of other holothurian species and 63.51 % to that of Acanthaster planci. The phylogenetic tree showed that the echinozoan OSCsclustered together, and then they formeda sister group to fungi and plant homologs. Chiridota sp. OSC catalyzed 2,3-Oxidosqualene into parkeol.Under high pressure, the relative enzymatic activity and stability of cyclase inChiridota sp. was higher than that in the shallow-sea holothurianStichopus horrens. The newly cloned OSC of Chiridota sp.provideskey information for the interpretation of the saponin synthesis pathway in deep-sea holothurians.


Subject(s)
Intramolecular Transferases , Triterpenes , Phylogeny , Triterpenes/metabolism , Cloning, Molecular , Oxidative Stress , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism
14.
Mol Genet Genomic Med ; 12(1): e2320, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37947113

ABSTRACT

BACKGROUND: Patients with biallelic variants in the lanosterol synthase (LSS) gene has been reported to exhibit phenotypes as follows: non-syndromic form of hypotrichosis, congenital cataracts, and alopecia with intellectual disability or growth retardation. However, genotype-phenotype correlations in the LSS gene are still not completely clear. METHODS: In this study, we reported a Chinese girl who had congenital cataracts with hypotrichosis. The trio exome sequencing was performed to elucidate the genetic cause of the patient. RESULTS: We identified compound heterozygous variants (c.296G>A, p.G99D and c.1025T>G, p.I342S) in the LSS gene. Both variants altered the amino acid coding at highly conserved amino acid residues and were predicted to be deleterious using prediction software. CONCLUSION: Our report expands the spectrum of variants in the LSS gene and will be helpful for genotype-phenotype correlations study.


Subject(s)
Cataract , Hypotrichosis , Intramolecular Transferases , Female , Humans , Hypotrichosis/genetics , Alopecia/genetics , Cataract/genetics , Amino Acids
15.
Microb Biotechnol ; 17(1): e14309, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37537795

ABSTRACT

As one of the main precursors, acetyl-CoA leads to the predominant production of even-chain products. From an industrial biotechnology perspective, extending the acyl-CoA portfolio of a cell factory is vital to producing industrial relevant odd-chain alcohols, acids, ketones and polyketides. The bioproduction of odd-chain molecules can be facilitated by incorporating propionyl-CoA into the metabolic network. The shortest pathway for propionyl-CoA production, which relies on succinyl-CoA catabolism encoded by the sleeping beauty mutase operon, was evaluated in Pseudomonas taiwanensis VLB120. A single genomic copy of the sleeping beauty mutase genes scpA, argK and scpB combined with the deletion of the methylcitrate synthase PVLB_08385 was sufficient to observe propionyl-CoA accumulation in this Pseudomonas. The chassis' capability for odd-chain product synthesis was assessed by expressing an acyl-CoA hydrolase, which enabled propionate synthesis. Three fed-batch strategies during bioreactor fermentations were benchmarked for propionate production, in which a maximal propionate titre of 2.8 g L-1 was achieved. Considering that the fermentations were carried out in mineral salt medium under aerobic conditions and that a single genome copy drove propionyl-CoA production, this result highlights the potential of Pseudomonas to produce propionyl-CoA derived, odd-chain products.


Subject(s)
Intramolecular Transferases , Propionates , Propionates/metabolism , Acyl Coenzyme A/metabolism , Pseudomonas/genetics , Pseudomonas/metabolism , Minerals
16.
New Phytol ; 241(2): 764-778, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37904576

ABSTRACT

Bioactive triterpenes feature complex fused-ring structures, primarily shaped by the first-committed enzyme, 2,3-oxidosqualene cyclases (OSCs) in plant triterpene biosynthesis. Triterpenes with B,C-ring-opened skeletons are extremely rare with unknown formation mechanisms, harbouring unchartered chemistry and biology. Here, through mining the genome of Chenopodium quinoa followed by functional characterization, we identified a stress-responsive and neofunctionalized OSC capable of generating B,C-ring-opened triterpenes, including camelliol A and B and the novel (-)-quinoxide A as wax components of the specialized epidermal bladder cells, namely the quinoxide synthase (CqQS). Protein structure analysis followed by site-directed mutagenesis identified key variable amino acid sites underlying functional interconversion between pentacyclic ß-amyrin synthase (CqbAS1) and B,C-ring-opened triterpene synthase CqQS. Mutation of one key residue (N612K) in even evolutionarily distant Arabidopsis ß-amyrin synthase could generate quinoxides, indicating a conserved mechanism for B,C-ring-opened triterpene formation in plants. Quantum computation combined with docking experiments further suggests that conformations of conserved W613 and F413 of CqQS might be key to selectively stabilizing intermediate carbocations towards B,C-ring-opened triterpene formation. Our findings shed light on quinoa triterpene skeletal diversity and mechanisms underlying B,C-ring-opened triterpene biosynthesis, opening avenues towards accessing their chemistry and biology and paving the way for quinoa trait engineering and quality improvement.


Subject(s)
Chenopodium quinoa , Intramolecular Transferases , Triterpenes , Chenopodium quinoa/metabolism , Triterpenes/metabolism , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism
17.
Plant Physiol ; 194(4): 2580-2599, 2024 Mar 29.
Article in English | MEDLINE | ID: mdl-38101922

ABSTRACT

Triterpenes are a class of bioactive compounds with diverse biological functions, playing pivotal roles in plant defense against biotic stressors. Oxidosqualene cyclases (OSCs) serve as gatekeepers in the biosynthesis of triterpenes. In this study, we utilized a Nicotiana benthamiana heterologous expression system to characterize NaOSC1 from Nicotiana attenuata as a multifunctional enzyme capable of synthesizing lupeol, dammarenediol II, 3-alpha,20-lupanediol, and 7 other triterpene scaffolds. We also demonstrated that NaOSC2 is, in contrast, a selective enzyme, producing only the ß-amyrin scaffold. Through virus-induced gene silencing and in vitro toxicity assays, we elucidated the roles of NaOSC1 and NaOSC2 in the defense of N. attenuata against Manduca sexta larvae. Metabolomic and feature-based molecular network analyses of leaves with silenced NaOSC1 and NaOSC2 unveiled 3 potential triterpene glycoside metabolite clusters. Interestingly, features identified as triterpenes within these clusters displayed a significant negative correlation with larval mass. Our study highlights the pivotal roles of NaOSC1 and NaOSC2 from N. attenuata in the initial steps of triterpene biosynthesis, subsequently influencing defense against M. sexta through the modulation of downstream triterpene glycoside compounds.


Subject(s)
Intramolecular Transferases , Manduca , Triterpenes , Animals , Nicotiana/genetics , Triterpenes/metabolism , Pentacyclic Triterpenes , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , Larva/metabolism
18.
PLoS One ; 18(11): e0291267, 2023.
Article in English | MEDLINE | ID: mdl-37939088

ABSTRACT

The chemical modification of RNA bases represents a ubiquitous activity that spans all domains of life. Pseudouridylation is the most common RNA modification and is observed within tRNA, rRNA, ncRNA and mRNAs. Pseudouridine synthase or 'PUS' enzymes include those that rely on guide RNA molecules and others that function as 'stand-alone' enzymes. Among the latter, several have been shown to modify mRNA transcripts. Although recent studies have defined the structural requirements for RNA to act as a PUS target, the mechanisms by which PUS1 recognizes these target sequences in mRNA are not well understood. Here we describe the crystal structure of yeast PUS1 bound to an RNA target that we identified as being a hot spot for PUS1-interaction within a model mRNA at 2.4 Å resolution. The enzyme recognizes and binds both strands in a helical RNA duplex, and thus guides the RNA containing the target uridine to the active site for subsequent modification of the transcript. The study also allows us to show the divergence of related PUS1 enzymes and their corresponding RNA target specificities, and to speculate on the basis by which PUS1 binds and modifies mRNA or tRNA substrates.


Subject(s)
Intramolecular Transferases , Saccharomyces cerevisiae , Saccharomyces cerevisiae/metabolism , RNA, Messenger/metabolism , RNA/metabolism , Intramolecular Transferases/genetics , Intramolecular Transferases/metabolism , RNA, Transfer/metabolism , Pseudouridine/metabolism
19.
Angew Chem Int Ed Engl ; 62(48): e202313429, 2023 11 27.
Article in English | MEDLINE | ID: mdl-37840440

ABSTRACT

The oxidosqualene cyclase (OSC) catalyzed cyclization of the linear substrate (3S)-2,3-oxidosqualene to form diverse pentacyclic triterpenoid (PT) skeletons is one of the most complex reactions in nature. Friedelin has a unique PT skeleton involving a fascinating nine-step cation shuttle run (CSR) cascade rearrangement reaction, in which the carbocation formed at C2 moves to the other side of the skeleton, runs back to C3 to yield a friedelin cation, which is finally deprotonated. However, as crystal structure data of plant OSCs are lacking, it remains unknown why the CSR cascade reactions occur in friedelin biosynthesis, as does the exact catalytic mechanism of the CSR. In this study, we determined the first cryogenic electron microscopy structure of a plant OSC, friedelin synthase, from Tripterygium wilfordii Hook. f (TwOSC). We also performed quantum mechanics/molecular mechanics simulations to reveal the energy profile for the CSR cascade reaction and identify key residues crucial for PT skeleton formation. Furthermore, we semirationally designed two TwOSC mutants, which significantly improved the yields of friedelin and ß-amyrin, respectively.


Subject(s)
Intramolecular Transferases , Triterpenes , Triterpenes/chemistry , Intramolecular Transferases/genetics , Catalysis , Cations
20.
Transfus Med Rev ; 37(3): 150748, 2023 07.
Article in English | MEDLINE | ID: mdl-37827586

ABSTRACT

Biphosphoglycerate mutase (BPGM) is a tri-functional enzyme expressed exclusively in erythroid cells and tissues that is responsible for the production of 2,3-biphosphoglycerate (2,3-BPG) through the Rapoport-Luebering shunt. The 2,3-BPG is required for efficient glycolysis and ATP production under anaerobic conditions, but is also a critical allosteric regulator of hemoglobin (Hb), acting to regulate oxygen release in peripheral tissues. In humans, BPGM deficiency is very rare, and is associated with reduced levels of erythrocytic 2,3-BPG and ATP, left shifted Hb-O2 dissociation curve, low P50, elevated Hb and constitutive erythrocytosis. BPGM deficiency in mice recapitulates the erythroid defects seen in human patients. A recent report has shown that BPGM deficiency in mice affords striking protection against both severe malaria anemia and cerebral malaria. These findings are reminiscent of studies of another erythrocyte specific glycolytic enzyme, Pyruvate Kinase (PKLR), which mutational inactivation protects humans and mice against malaria through impairment of glycolysis and ATP production in erythrocytes. BPGM, and PKLR join glucose-6-phosphate dehydrogenase (G6PD) and other erythrocyte variants as modulating response to malaria. Recent studies reviewed suggest glycolysis in general, and BPGM in particular, as a novel pharmacological target for therapeutic intervention in malaria.


Subject(s)
Intramolecular Transferases , Malaria , Humans , Mice , Animals , Erythrocytes , Hemoglobins , Oxygen , Malaria/drug therapy , Adenosine Triphosphate
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