Site-directed mutagenesis enhances the activity of benzylidene acetone synthase of polyketide synthase from Polygonum cuspidatum / 生物工程学报

Polygonum cuspidatum polyketide synthase 1 (PcPKS1) has the catalytic activity of chalcone synthase (CHS) and benzylidene acetone synthase (BAS), which can catalyze the production of polyketides naringenin chalcone and benzylidene acetone, and then catalyze the synthesis of flavonoids or benzylidene acetone. In this study, three amino acid sites (Thr133, Ser134, Ser33) that may affect the function of PcPKS1 were identified by analyzing the sequences of PcPKS1, the BAS from Rheum palmatum and the CHS from Arabidopsis thaliana, as well as the conformation of the catalytic site of the enzyme. Molecular modification of PcPKS1 was carried out by site-directed mutagenesis, and two mutants were successfully obtained. The in vitro enzymatic reactions were carried out, and the differences in activity were detected by high performance liquid chromatography (HPLC). Finally, mutants T133LS134A and S339V with bifunctional activity were obtained. In addition to bifunctional activities of BAS and CHS, the modified PcPKS1 had much higher BAS activity than that of the wild type PcPKS1 under the conditions of pH 7.0 and pH 9.0, respectively. It provides a theoretical basis for future use of PcPKS1 in genetic engineering to regulate the biosynthesis of flavonoids and raspberry ketones.

Novel Pathogenic Mutation of PNPLA1 Identified in Autosomal Recessive Congenital Ichthyosis: A Case Report / 中国医学科学杂志(英文版)

Autosomal recessive congenital ichthyosis (ARCI) is characterized by being born as collodion babies, hyperkeratosis, and skin scaling. We described a collodion baby at birth with mild ectropion, eclabium, and syndactyly. Whole exome sequencing showed a compound heterozygous variant c.[56C>A], p.(Ser19X) and c.[100G>A], p.(Ala34Thr) in the PNPLA1 gene [NM_001145717; exon 1]. The protein encoded by PNPLA1 acts as a unique transacylase that specifically transfers linoleic acid from triglyceride to ω-hydroxy fatty acid in ceramide, thus giving rise to ω-O-acylceramide, a particular class of sphingolipids that is essential for skin barrier function. The variant was located in the patatin core domain of PNPLA1 and resulted in a truncated protein which could disrupt the function of the protein. This case report highlights a novel compound heterozygous mutation in PNPLA1 identified in a Chinese child.

Cloning and function analysis of chalcone isomerase gene and chalcone synthase gene in Lonicera macranthoides / 中国中药杂志

In order to explore the functions of genes of key rate-limiting enzymes chalcone isomerase(CHI) and chalcone synthase(CHS) in the biosynthesis of flavonoids in Lonicera macranthoides, this study screened and cloned the cDNA sequences of CHI and CHS genes from the transcriptome data of conventional variety and 'Xianglei' of L. macranthoides. Online bioinformatics analysis software was used to analyze the characteristics of the encoded proteins, and quantitative reverse-transcription polymerase chain reaction(qRT-PCR) to detect the expression of CHI and CHS in different parts of the varieties at different flowering stages. The content of luteo-loside was determined by high performance liquid chromatography(HPLC) and the correlation with the expression of the two genes was analyzed. The results showed that the CHI and CHS of the two varieties contained a 627 bp and 1170 bp open reading frame(ORF), respectively, and the CHI protein and CHS protein were stable, hydrophilic, and non-secretory. qRT-PCR results demonstrated that CHI and CHS of the two varieties were differentially expressed in stems and leaves at different flowering stages, particularly the key stages. Based on HPLC data, luteoloside content was in negative correlation with the relative expression of the genes. Thus, CHI and CHS might regulate the accumulation of flavonoids in L. macranthoides, and the specific functions should be further studied. This study cloned CHI and CHS in L. macranthoides and analyzed their expression for the first time, which laid a basis for investigating the molecular mechanism of the differences in flavonoids such as luteoloside in L. macranthoides and variety breeding.

Structure, function and application of serine carboxypeptidase-like acyltransferases from plants / 生物工程学报

Plant serine carboxypeptidase-like acyltransferases (SCPL-AT) have similar structural characteristics and high homology compared to the serine carboxypeptidase. They can transfer the acyl from acyl glucose esters to many natural products, participate in the acylation modification of plant secondary metabolites, enrich the structural diversity of natural products, and improve the physicochemical properties such as water solubility and stability of compounds. This review summarizes the structural characteristics, catalytic mechanism, functional characterization, and biocatalytic applications of SCPL-AT from plants. This will help to promote the functional characterization of these acyltransferase genes and the biosynthesis of useful plant secondary metabolites by synthetic biotechnology.

Cloning and characterization of chalcone synthase and chalcone isomerase genes in Arisaema heterophyllum / 中国中药杂志

Chalcone synthase( CHS) and chalcone isomerase( CHI) are key enzymes in the biosynthesis pathway of flavonoids. In this study,unigenes for CHS and CHI were screened from the transcriptome database of Arisaema heterophyllum. The open reading frame( ORFs) of chalcone synthase( Ah CHS) and chalcone isomerase( Ah CHI) were cloned from the plant by RT-PCR. The physicochemical properties,expression and structure characteristics of the encoded proteins Ah CHS and Ah CHI were analyzed. The ORFs of Ah CHS and Ah CHI were 1 176,630 bp in length and encoded 392,209 amino acids,respectively. Ah CHS functioned as a symmetric homodimer. The N-terminal helix of one monomer entwined with the corresponding helix of another monomer. Each CHS monomer consisted of two structural domains. In particular,four conserved residues define the active site. The tertiary structure of Ah CHI revealed a novel open-faced β-sandwich fold. A large β-sheet( β4-β11) and a layer of α-helices( α1-α7) comprised the core structure. The residues spanning β4,β5,α4,and α6 in the three-dimensional structure were conserved among CHIs from different species. Notably,these structural elements formed the active site on the protein surface,and the topology of the active-site cleft defined the stereochemistry of the cyclization reaction. The homology comparison showed that Ah CHS had the highest similarity to the CHS of Anthurium andraeanum,while Ah CHI had the highest similarity to the CHI of Paeonia delavayi. This study provided the basis for the functional study of Ah CHS and Ah CHI and the further study on plant flavonoid biosynthesis pathway.

MicroRNA-340-5p modulates cisplatin resistance by targeting LPAATβ in osteosarcoma

MicroRNAs (miRNAs) play an important role in drug resistance and modulate the efficiency of chemotherapy. A recent study indicated that miR-340 functions as a tumor suppressor in various types of cancer. However, the role of miR-340 in chemotherapy has not been reported yet. In this study, we found that miR-340 enhanced cisplatin (CDDP)-induced cell death. Induction of miR-340-5p expression decreased the IC50 of CDDP and increased the apoptosis of CDDP-resistant MG-63 and Saos-2 cells. Moreover, miR-340-5p decreased the accumulation of MRP1 and MDR1. We further explored the mechanism underlying the promoting effects of miR-340-5p on CDDP-induced cell death. We identified a potential target of miR-340 in the 3′ untranslated region of lysophosphatidic acid acyltransferase (LPAATβ) using the online program Targetscan (http://www.microrna.org). Luciferase reporter assays showed that miR-340 binds to the 3′UTR of LPAATβ. Enforced expression of miR-340-5p decreased the accumulation of LPAATβ in both MG-63 and Saos-2 cells. Silencing LPAATβ decreased the IC50 of CDDP and increased the apoptosis of CDDP-resistant MG-63 and Saos-2 cells, which is consistent with the effect of miR-340-5p on CDDP-induced cell death. Moreover, induced expression of LPAATβ compromised the effects of miR-340-5p on CDDP-induced cell death and accumulation of MRP1 and MDR1. Taken together, our data indicated that miR-340-5p enhanced the sensitivity to CDDP by targeting LPAATβ.

Interaction of antimicrobial peptide with mycolyl transferase in Mycobacterium tuberculosis

It is estimated that about 40% of the Indian population are infected with tuberculosis [TB] and that 3,000,000 people die as a result of TB annually. TB is caused by Mycobacterium tuberculosis. In 2011, the World Health Organization declared India as having the highest TB burden worldwide. An important criteria for pathogenicity is the presence of mycolic acid linked to the protective outer membrane of bacteria. Mycolyl transferase catalyzes the transfer of mycolic acid and promotes cell wall synthesis. This is also considered as a novel target for drug-mediated intervention strategies. Here, we have attempted to understand the interaction between the antimicrobial peptide [AMP], dermcidin, and mycolyl transferase in M. tuberculosis using a computational approach. The present study was undertaken in order to elucidate the capability of AMPs to treat this bacteria, which is less sensitive to available antibiotics, and to design a novel method for new therapies

Cloning and expression analysis of a hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferasegene(IiHCT) from Isatis indigotica / 中国中药杂志

Based on the transcriptome data, we cloned the open reading frame of IiHCT gene from Isatis indigotica, and then performed bioinformatic analysis of the sequence. Further, we detected expression pattern in specific organs and hairy roots treated methyl jasmonate( MeJA) by RT-PCR. The IiHCT gene contains a 1 290 bp open reading frame( ORF) encoding a polypeptide of 430 amino acids. The predicted isoelectric point( pI) was 5.7, a calculated molecular weight was about 47.68 kDa. IiHCT was mainly expressed in stem and undetectable in young root, leaf and flower bud. After the treatment of MeJA, the relative expression level of IiHCT increased rapidly. The expression level of IiHCT was the highest at 4 h and maintained two fold to control during 24 h. In this study, cloning of IiHCT laid the foundation for illustrating the biosynthesis mechanism of phenylpropanoids in I. indigotica.

Regulation of N-Myristoyltransferase by the Calpain and Caspase Systems.

N-myristoyltransferase (NMT) is an essential eukaryotic enzyme which catalyzes the transfer of the myristoyl group to the terminal glycine residue of a number of proteins including those involved in signal transduction and apoptotic pathways. In higher eukaryotes, two isoforms of NMT have been identified (NMT1 and NMT2) which share about 76% amino acid sequence identity in humans. Protein-protein interactions of NMTs reveal that m-calpain interacts with NMT1 whereas caspase-3 interacts with NMT2. These findings reveal differential interactions of both isoforms of NMT with various signaling molecules. This minireview provides an overview of the regulation of N-myristoyltransferase by calpain and caspase systems.

Expression pattern of Mycobacterium tuberculosis Ag85B and its value in pathological diagnosis / 中华病理学杂志

<p><b>OBJECTIVE</b>To detect the expression of Mycobacterium tuberculosis secreted protein Ag85B in paraffin-embedded tissues by immunohistochemistry (IHC), and to evaluate its application in the pathological diagnosis of tuberculosis.</p><p><b>METHODS</b>One hundred and five tuberculosis specimens (54 pulmonary tuberculosis, 51 lymph nodal tuberculosis) and 51 specimens of other diseases (8 lung cancer, 10 pulmonary abscess, 10 bronchiectasis, 7 lymphoma, 5 necrotizing lymphadenitis, 4 reactive hyperplasia lymphoid, and 7 sarcoidosis) were collected from January 2012 to July 2013 from Beijing Chest Hospital, Capital Medical University. One-step IHC was performed on paraffin-embedded tissues using antibody directed against Ag85B.</p><p><b>RESULTS</b>IHC and Ziehl-Neelsen (ZN) acid-fast staining showed that distribution and intensity of Ag85B expression were concordant with the distribution and number of acid-fast bacilli. IHC showed significantly higher sensitivity than ZN staining (50.5%, 53/105 vs. 31.4%, 33/105; χ² = 7.877, P = 0.005). The combined sensitivity of IHC and ZN staining was 59.0%. Moreover, oil immersion was not necessary for IHC, allowing more rapid diagnosis.</p><p><b>CONCLUSION</b>IHC detection of Ag85B is a simple method with higher sensitivity than ZN staining, and demonstrated good value in the pathological diagnosis of tuberculosis.</p>

Construction and expression of a eukaryotic vector co-expressing immunodominant antigens of CFP10, ESAT6, Ag85A and Ag85B of Mycobacterium tuberculosis / 生物工程学报

CFP10, ESAT6, Antigen 85A (Ag85A) and antigen 85B (Ag85B) are the key immunodominant antigens of Mycobacterium tuberculosis. In order to construct a eukaryotic vector able to co-express the four genes in one vector, we amplified the target gene fragments encoding the CFP10, ESAT6, Ag85A and Ag85B antigens and inserted them into the multicloning site of the shuttle plasmid vector pcDNA3.1 (+), of which the CFP10 and ESAT6 encoding genes were in frame fused with a linker encoding (Gly4Ser)3 residue, before the fused gene was inserted downstream of CMV promoter with a bovine growth hormone poly A(BGH pA) sequence at the 3'-end; Ag85A and Ag85B encoding genes were fused with a separation of internal ribosome entry site (IRES) sequence before the fused gene cassette was inserted downstream of RSV promoter with a BGH pA sequence at the 3'-end. The final plasmid containing all four genes was confirmed by sequence analysis and designated as pcDNA-CFP10-ESAT6-Ag85A-Ag85B (pcDNA-CEAB). In order to verify the ability of this construct to express target proteins, we then transfected the recombinant plasmid into Human embryonic kidney (HEK) 293T cells and harvested the cell lysates, and the cell lysates were then separated by SDS-PAGE and subjected to Western blot analysis 48 h after transfection. All four of the target proteins were detected in the cell lysates against the respective specific antibodies, suggesting that we have successfully constructed a eukaryotic vector co-expressing the four immunodominant antigens of Mycobacterium tuberculosis, which lay a foundation for the further study of the immunogenicity and protective activity of the four antigens.

Advances of resveratrol synthase gene in the application of genetic engineering and biofunctional investigation / 生物工程学报

Resveratrol synthase (RS) plays a key role in resveratrol (Res) biosynthesis. RS gene has been formerly reported to be transformed into many plant species and microorganisms, and to play certain roles in metabolic and regulation processes. In this paper, the transformations of RS gene in plants, and the related changes of biological properties, such as metabolites, anti-pathogen activities, anti-radical properties, and developmental characters in transgenic plants, as well as the production of resveratrol in microbes by utilizing RS gene were summarized. Moreover, the application prospects of RS gene in bioengineering were also addressed.

Expression of 4"-O-isovaleryltransferase gene from Streptomyces thermotolerans in Streptomyces lividans TK24 / 生物工程学报

4"-O-isovaleryltransferase gene (ist) was regulated by positive regulatory genes of midecamycin 4"-O-propionyltransferase gene (mpt) in Streptomyces lividans TK24. A BamH I ~8.0 kb fragment from Streptomyces mycarofaciens 1748 was proved that it contained mpt gene and linked with two positive regulatory genes, orf27 and orf28. Orf of mpt was replaced by orf of ist and linked with two regulatory genes or orf27 single, and individually cloned into the vectors pKC1139 or pWHM3 (high copy number), and then transformed into S. lividans TK24. The levels of mpt and ist expression were evaluated by the bio-tramsformation efficacy of spiramycin into 4"-O-acylspiramycins in these transformants. The results showed that 4"-O-isovalerylspiramycins could be detected only in the transformants containing the plasmids constructed with pWHM3. The efficacy of bio-transformation of the transformants containing two regulatory genes was higher than that of orf27 single. So, the positive regulatory genes system of mpt gene could enhance ist gene expression.

Comparison of stilbene synthase from different plant sources for resveratrol biosynthesis / 生物工程学报

Resveratrol is a natural phytoalexin with special pharmacological and health functions. Stilbene synthase (STS) is a key and rate-limiting enzyme in the biosynthesis of resveratrol that is present only in a limited number of plants. The content of resveratrol from Polygonum cuspidatum is more than 1000 times higher than grapes and peanuts. We speculate that the catalytic ability of different STS may be one of the reasons causing differences in the content of resveratrol. To verify the above speculation, Vitis vinifera stilbene synthase gene (VvSTS) was amplified according to overlap PCR protocol with genomic DNA as template. VvSTS and PcSTS (PcPKS5) were analyzed through heterologous expression in Escherichia coli. The expression products were purified with Ni-NTA sepharose affinity chromatography and desalted through PD-10 column. The molecular weight of the two fusion proteins was about 43 kDa. Enzyme reaction and product analysis showed that the two products were resveratrol. The enzyme kinetic analysis showed that the catalyze efficiency (Kcat/Km) of PcPKS5 was 2.4 times of the VvSTS. Our findings confirms that STS from certain plants has much higher catalytic capability.

Cloning and bioinformatics analysis of chalcone synthase (AsCHS1) gene in Aquilaria sinensis / 中国中药杂志

<p><b>OBJECTIVE</b>The study aimed to clone the open reading frame of chalcone synthase (CHS) from Aquilaria sinensis and analyze the bioinformatics and expression of the gene.</p><p><b>METHOD</b>One unique sequence containing CHS domain was discovered in our previous reported wound transcriptome dataset of A. sinensis. The open reading frame of CHS was cloned by RT-PCR strategy with the template of mixed RNA extracted from A. sinensis stem which treated by different wound time. The bioinformatic analysis of this gene and its corresponding protein was performed. The AsCHS1 expression in calli was analyzed with histone gene as an internal control gene under wound condition by qRT-PCR technique.</p><p><b>RESULT</b>One unique sequence of CHS, named as AsCHS1, was cloned from A. sinensis. The full length of AsCHS1 cDNA was containing a 1 192 bp ORF that encoded 397 amino acids. The result of qRT-PCR displayed that the highest expression level was at 12 h, which indicated that it was possibly involved in early-stage response to wound.</p><p><b>CONCLUSION</b>Cloning and analyzing AsCHS1 gene from A. sinensis provided basic information for study the function and expression regulation of AsCHS1 in the flavonoids biosynthesis.</p>

Relationship between expression of chalcone synthase gene (CHS) and scutellarin content in Erigeron breviscapus / 中国中药杂志

<p><b>OBJECTIVE</b>Scutellarin from Erigeron breviscapus is a flavonoid with remarkable pharmacological activity, whose route of biosynthesis is still fully clear. Chalcone synthase (CHS) is the key enzyme regulating flavonoids biosynthesis, and the aim of this study is to explain the relationship between patterns of the gene expression and scutellarin content through studying CHS gene expression patterns combined with scutellarin content in various parts of E. breviscapus.</p><p><b>METHOD</b>Through RT-PCR and RACE, the full length of CHS was cloned and analyzed by fluorescent quantitative PCR. The scutellarin content in tissues was analyzed by HPLC.</p><p><b>RESULT</b>The full-length gene sequence was 1 270 bp, encoding 405 amino acids. Software analysis found that the DNA sequence was 80% similarity with Compositae plant homeo-box gene. Fluorescence quantitative analysis showed that CHS had the highest expression level in leaves, far higher than that in root, stem and flower. HPLC analysis showed that the scutellarin was the highest in leaves, followed by the flowers and stems, scutellarin was not detected in root.</p><p><b>CONCLUSION</b>Correlation analysis showed that CHS expression amount and scutellarin content in different parts of E. breviscapus is positive correlation (r = 0.761, P < 0.05), it suggests that CHS gene expression level has important effect on biosynthesis of scutellarin.</p>

Virulence potential and antibiotic susceptibility pattern of motile aeromonads associated with freshwater ornamental fish culture systems: a possible threat to public health

Aeromonas spp. are ubiquitous aquatic organisms, associated with multitude of diseases in several species of animals, including fishes and humans. In the present study, water samples from two ornamental fish culture systems were analyzed for the presence of Aeromonas. Nutrient agar was used for Aeromonas isolation, and colonies (60 No) were identified through biochemical characterization. Seven clusters could be generated based on phenotypic characters, analyzed by the programme NTSYSpc, Version 2.02i, and identified as: Aeromonas caviae (33.3%), A. jandaei (38.3%) and A. veronii biovar sobria (28.3%). The strains isolated produced highly active hydrolytic enzymes, haemolytic activity and slime formation in varying proportions. The isolates were also tested for the enterotoxin genes (act, alt and ast), haemolytic toxins (hlyA and aerA), involved in type 3 secretion system (TTSS: ascV, aexT, aopP, aopO, ascF-ascG, and aopH), and glycerophospholipid-cholesterol acyltransferase (gcat). All isolates were found to be associated with at least one virulent gene. Moreover, they were resistant to frequently used antibiotics for human infections. The study demonstrates the pathogenic potential of Aeromonas, associated with ornamental fish culture systems suggesting the emerging threat to public health.

Lipid homeostasis and the formation of macrophage-derived foam cells in atherosclerosis

Atherosclerosis is a chronic, inflammatory disorder characterized by the deposition of excess lipids in the arterial intima. The formation of macrophage-derived foam cells in a plaque is a hallmark of the development of atherosclerosis. Lipid homeostasis, especially cholesterol homeostasis, plays a crucial role during the formation of foam cells. Recently, lipid droplet-associated proteins, including PAT and CIDE family proteins, have been shown to control the development of atherosclerosis by regulating the formation, growth, stabilization and functions of lipid droplets in macrophage-derived foam cells. This review focuses on the potential mechanisms of formation of macrophage-derived foam cells in atherosclerosis with particular emphasis on the role of lipid homeostasis and lipid droplet-associated proteins. Understanding the process of foam cell formation will aid in the future discovery of novel therapeutic interventions for atherosclerosis.

Plant-specific type III polyketide synthases superfamily: crystal structures and functions / 生物工程学报

Plant type III polyketide synthase (PKS) generates backbones of a variety of plant secondary metabolites with diverse functions, and has long been models to elucidate the relationship between the three-dimensional structure and function. More than 80 type IIII PKS crystal structures with different functions have been reported in Protein Data Bank, including the crystal structures of the well-studied Chalcone Synthase of plant type III PKS, as well as the 6 other kinds of PKSs in the family, which are critical for understanding the structural basis for diverse starter molecule selectivity, polyketide chain length and the cyclization reaction. Structure-based analysis and site-directed mutagenesis are foundation for the investigation of enzyme engineering, genetic and metabolic engineering. This review summarized 7 plant-specific type III PKS in the aspects of their crystal structures and functions.

Effect of different developmental stage on plant growth and active compounds in Scutellaria baicalensis / 中国中药杂志

<p><b>OBJECTIVE</b>To study the developmental phase on the growth and active compounds in Scutellaria baicalensis.</p><p><b>METHOD</b>Seeds of wild plants were collected from Laiwu and sowed in Fangshan (Beijing) and Laiwu (Shandong). Samples of aerial and underground parts were collected in five growth periods of sprouts, seedlings, flowering, seed drop and withered periods respectively. The length of taproot, fresh weight of root, diameter of taproot and the length of stem were determined. The content of active compounds and total flavonoids were determined by HPLC and ultraviolet spectrophotometry respectively. The transcripted level of PAL1, PAL2, PAL3, C4H, 4CL, CHS, GUS and UBGAT were analyzed with RT-PCR.</p><p><b>RESULT</b>The results showed that the aerial part of S. baicalensis grew quickly before flowering stage, and the underground part grew mostly between the periods of flowering and withered. In the whole growing developmental periods, the content of total flavonoids was not changed significantly, the content of baicalin was increased gradually and the content of baicalein was decreased gradually. Expression level of PAL and 4CL was the highest in withered period, CHS was increased between flowering and seed drop and decreased in withered period.</p><p><b>CONCLUSION</b>Seedlings and withered periods may be the key phase affecting the growth and active compounds in S. baicalensis.</p>