Immobilization of BoPAL3 Phenylalanine Ammonia-Lyase on Electrospun Nanofibrous Membranes of Polyvinyl Alcohol/Nylon 6/Chitosan Crosslinked with Dextran Polyaldehyde.

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.24) is common in plants and catalyzes the formation of trans-cinnamic acid and ammonia via phenylalanine deamination. Recombinant Bambusa oldhamii BoPAL3 protein expressed in Escherichia coli was immobilized on an electrospun nanofibrous membrane using dextran polyaldehyde as a crosslinker. The immobilized BoPAL3 protein exhibited comparable kinetic properties with the free BoPAL3 protein and could be recycled for six consecutive cycles compared with the free BoPAL3 protein. The residual activity of the immobilized BoPAL3 protein was 84% after 30 days of storage at 4 °C, whereas the free BoPAL3 protein retained 56% residual activity in the same storage conditions. Furthermore, the resistance of the immobilized BoPAL3 protein to chemical denaturants was greatly increased. Therefore, the BoPAL3 protein can be immobilized using the natural dextran polyaldehyde crosslinker in place of the conventional chemical crosslinker. Nanofibrous membranes made from polyvinyl alcohol (PVA), nylon 6, and chitosan (CS) are incredibly stable and useful for future industrial applications.

Recombinant Streptomyces netropsis transglutaminase expressed in Komagataella phaffii (Pichia pastoris) and applied in plant-based chicken nugget.

Transglutaminase (TG, EC 2.3.2.13) is widely used to modify functional properties in food systems, which can catalyze cross-linking reaction of proteins. In this work, microbial transglutaminase (MTG) from Streptomyces netropsis was heterologously expressed in the methylotrophic yeast Komagataella phaffii (Pichia pastoris). The specific activity of recombinant microbial transglutaminase (RMTG) was 26.17 ± 1.26 U/mg, and the optimum pH and temperature were measured as 7.0 and 50 °C, respectively. Bovine serum albumin (BSA) was used as a substrate to evaluate the effect of cross-linking reaction, and we found that RMTG had significant (p < 0.05) cross-linking effect for more than 30 min reactions. RMTG was further utilized in the investigation of plant-based chicken nuggets. Results showed that the hardness, springiness and chewiness of nuggets increased, and the adhesiveness decreased after RMTG treatment, which can prove that RMTG has the potential to improve the texture properties of plant-based chicken nuggets.

Cloning of Three Cytokinin Oxidase/Dehydrogenase Genes in Bambusa oldhamii.

Cytokinin oxidase/dehydrogenase (CKX) catalyzes the irreversible breakdown of active cytokinins, which are a class of plant hormones that regulate cell division. According to conserved sequences of CKX genes from monocotyledons, PCR primers were designed to synthesize a probe for screening a bamboo genomic library. Cloned results of three genes encoding cytokinin oxidase were named as follows: BoCKX1, BoCKX2, and BoCKX3. In comparing the exon-intron structures among the above three genes, there are three exons and two introns in BoCKX1 and BoCKX3 genes, whereas BoCKX2 contains four exons and three introns. The amino acid sequence of BoCKX2 protein shares 78% and 79% identity with BoCKX1 and BoCKX3 proteins, respectively. BoCKX1 and BoCKX3 genes are particularly closely related given that the amino acid and nucleotide sequence identities are more than 90%. These three BoCKX proteins carried putative signal peptide sequences typical of secretion pathway, and a GHS-motif was found at N-terminal flavin adenine dinucleotide (FAD) binding domain, suggesting that BoCKX proteins might covalently conjugate with an FAD cofactor through a predicted histidine residue.

Identification and characterization of immunomodulatory peptides from pepsin-soy protein hydrolysates.

To obtain immunomodulatory peptides from isolated soy protein (ISP), pepsin was selected to prepare hydrolysates and 4-h treatment (Pepsin-ISPH4h) showed the highest yield and immunomodulatory activities. The Pepsin-ISPH4h was sequentially fractionated by 30, 10 and 1-kDa molecular weight cut-off (MWCO) membranes, in which 1-kDa MWCO permeate (1P) exhibited the most significant enhancement of phagocytosis activity without causing excessive inflammation as compared with Pepsin-ISPH4h. To further purify and enhance the immunomodulatory activity, 1P was distinct by high-performance liquid chromatography equipped with a reverse-phase column and in vivo immunomodulatory activity of fractions was examined in mice. Fraction 1 (F1) significantly elevated phagocytosis activity of mice spleen macrophages and neutrophils. However, increase of phagocytosis activity did not result from the induction of macrophages M1 or M2 polarization. The immunomodulatory peptide sequence, EKPQQQSSRRGS, from F1 was identified by LC-MS/MS. Phagocytosis activity and macrophage M1 polarization were elevated by synthetic peptide treatment. Hence, our results indicated that isolated soy protein hydrolysates prepared by pepsin could provide a source of peptides with immunomodulatory effects.

Production of Trans-Cinnamic Acid by Immobilization of the Bambusa oldhamii BoPAL1 and BoPAL2 Phenylalanine Ammonia-Lyases on Electrospun Nanofibers.

Phenylalanine ammonia-lyase (PAL) catalyzes the nonoxidative deamination of phenylalanine to yield trans-cinnamic acid and ammonia. Recombinant Bambusa oldhamii BoPAL1/2 proteins were immobilized onto electrospun nanofibers by dextran polyaldehyde as a cross-linking agent. A central composite design (CCD)-response surface methodology (RSM) was utilized to optimize the electrospinning parameters. Escherichia coli expressed eBoPAL2 exhibited the highest catalytic efficiency among four enzymes. The optimum conditions for fabricating nanofibers were determined as follows: flow rate of 0.10 mL/h, voltage of 13.8 kV, and distance of 13 cm. The response surface models were used to obtain the smaller the fiber diameters as well as the highest PAL activity in the enzyme immobilization. Compared with free BoPALs, immobilized BoPALs can be reused for at least 6 consecutive cycles. The remained activity of the immobilized BoPAL proteins after storage at 4 °C for 30 days were between 75 and 83%. In addition, the tolerance against denaturants of the immobilized BoPAL proteins were significantly enhanced. As a result, the dextran polyaldehyde natural cross-linking agent can effectively replace traditional chemical cross-linking agents for the immobilization of the BoPAL enzymes. The PAL/nylon 6/polyvinyl alcohol (PVA)/chitosan (CS) nanofibers made are extremely stable and are practical for industrial applications in the future.

NLIP and HAD-like Domains of Pah1 and Lipin 1 Phosphatidate Phosphatases Are Essential for Their Catalytic Activities.

Saccharomyces cerevisiae Pah1 phosphatidate phosphatase (PAP) catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol, controlling phospholipids and triacylglycerol metabolisms. Pah1 and human Lipin 1 are intrinsically disordered proteins with 56% and 43% unfolded regions, respectively. Truncation analysis of the conserved and non-conserved regions showed that N- and C-conserved regions are essential for the catalytic activity of Pah1. PAP activities can be detected in the conserved N-terminal Lipin (NLIP) domain and C-terminal Lipin (CLIP)/haloacid dehalogenase (HAD)-like domain of Pah1 and Lipin 1, suggesting that the evolutionarily conserved domains are essential for the catalytic activity. The removal of disordered hydrophilic regions drastically reduced the protein solubility of Pah1. Thioredoxin is an efficient fusion protein for production of soluble NLIP-HAD recombinant proteins in Escherichia coli.

Cloning and characterization of the Bambusa oldhamii BoMDH-encoded malate dehydrogenase.

Malate dehydrogenase (MDH), which is ubiquitously occurred in nature, catalyzes the interconversion of malate and oxaloacetate. Higher plants contain multiple forms of MDH that differ in coenzyme specificity, subcellular localization and physiological function. A putative Bambusa oldhamii BoMDH cDNA was screened with the specific probe from the bamboo cDNA library. Sequence alignment shows that there's a high homology between the deduced amino acid sequence of BoMDH and MDH protein in Oryza sativa glyoxysome (92%). A 57 kDa fusion protein was expressed by IPTG induction in Escherichia coli BL21 (DE3), and an obvious MDH activity was detected in the recombinant protein. The molecular mass of recombinant BoMDH was estimated to be 120 kDa, and the subunit form was 57 kDa by denatured SDS-PAGE, indicating that BoMDH presents as a homodimer. The optimum temperature and pH for BoMDH activity were 40 °C and 9.5, respectively. The Km values of BoMDH for malate and NAD+ were 5.2 mM and 0.52 mM. The kcat/Km values of BoMDH for malate and NAD+ were 163 min-1 mM-1 and 3060 min-1 mM-1.

Enhancement of Agricultural Processed By-Products: Qualities Analysis of Fermentation Method in Gradient Salt Adding Treatment of Tuna Cooking Juice with Black Bean Koji Added.

Fish sauce is popular for fermenting food in Southeast and Eastern Asia, while black bean is used to ferment condiments in Taiwan. Researchers have recently investigated the use of fish and black bean sauce in places where combining both fish and black bean is rare. This study was focused on fish sauce made from concentrated tuna cooking juice mixed with black bean koji. The experiment was divided into two stages. In the pre-fermentation stage, a suitable fermentation time with no salt added was determined. In the later fermentation stage, two preformatted samples of 4 and 7 days were added to salt water at 20 °Bé. In the pre-fermentation stage, the results show that the protease activity increased as time passed, but the pH value decreased. The highest browning degree was achieved after 120 days. In the later fermentation period, the total nitrogen contents for both experimental groups of 4 days and 7 days reached up to twice that of soy sauce. The total nitrogen content increased with time. In addition, the level of ammonia nitrogen increased from 0.08 to 0.15 g/dL in the first month. In conclusion, a new flavor of fermented sauce was produced in a shorter time and more effectively by combining tuna cooking juice and black bean.

Yck1 casein kinase I regulates the activity and phosphorylation of Pah1 phosphatidate phosphatase from Saccharomyces cerevisiae.

The PAH1-encoded phosphatidate phosphatase in Saccharomyces cerevisiae plays a major role in triacylglycerol synthesis and the control of phospholipid synthesis. For its catalytic function on the nuclear/endoplasmic reticulum membrane, Pah1 translocates to the membrane through its phosphorylation/dephosphorylation. Pah1 phosphorylation on multiple serine/threonine residues is complex and catalyzed by diverse protein kinases. In this work, we demonstrate that Pah1 is phosphorylated by the YCK1-encoded casein kinase I (CKI), regulating Pah1 catalytic activity and phosphorylation. Phosphoamino acid analysis coupled with phosphopeptide mapping of the CKI-phosphorylated Pah1 indicated that it is phosphorylated mainly on multiple serine residues. Using site-directed mutagenesis and phosphorylation analysis of Pah1, we identified eight serine residues (i.e. Ser-114, Ser-475, Ser-511, Ser-602, Ser-677, Ser-705, Ser-748, and Ser-774) as the target sites of CKI. Of these residues, Ser-475 and Ser-511 were specific for CKI, whereas the others were shared by casein kinase II (Ser-705), Cdc28-cyclin B (Ser-602), Pho85-Pho80 (Ser-114, Ser-602, and Ser-748), protein kinase A (Ser-667 and Ser-774), and protein kinase C (Ser-677). CKI-mediated phosphorylation of Pah1 stimulated both its phosphatidate phosphatase activity and its subsequent phosphorylation by casein kinase II. However, the CKI-mediated phosphorylation of Pah1 strongly inhibited its subsequent phosphorylation by Pho85-Pho80, protein kinase A, and protein kinase C. In a reciprocal analysis, Pah1 phosphorylation by Pho85-Pho80 inhibited subsequent phosphorylation by CKI. CKI-mediated Pah1 phosphorylation was also inhibited by a peptide containing the Pah1 residues 506-517, including the kinase-specific Ser-511 residue. These findings advance our understanding of how Pah1 catalytic activity and phosphorylation are regulated by multiple protein kinases.

Phosphorylation of Yeast Pah1 Phosphatidate Phosphatase by Casein Kinase II Regulates Its Function in Lipid Metabolism.

Pah1 phosphatidate phosphatase in Saccharomyces cerevisiae catalyzes the penultimate step in the synthesis of triacylglycerol (i.e. the production of diacylglycerol by dephosphorylation of phosphatidate). The enzyme playing a major role in lipid metabolism is subject to phosphorylation (e.g. by Pho85-Pho80, Cdc28-cyclin B, and protein kinases A and C) and dephosphorylation (e.g. by Nem1-Spo7) that regulate its cellular location, catalytic activity, and stability/degradation. In this work, we show that Pah1 is a substrate for casein kinase II (CKII); its phosphorylation was time- and dose-dependent and was dependent on the concentrations of Pah1 (Km = 0.23 µm) and ATP (Km = 5.5 µm). By mass spectrometry, truncation analysis, site-directed mutagenesis, phosphopeptide mapping, and phosphoamino acid analysis, we identified that >90% of its phosphorylation occurs on Thr-170, Ser-250, Ser-313, Ser-705, Ser-814, and Ser-818. The CKII-phosphorylated Pah1 was a substrate for the Nem1-Spo7 protein phosphatase and was degraded by the 20S proteasome. The prephosphorylation of Pah1 by protein kinase A or protein kinase C reduced its subsequent phosphorylation by CKII. The prephosphorylation of Pah1 by CKII reduced its subsequent phosphorylation by protein kinase A but not by protein kinase C. The expression of Pah1 with combined mutations of S705D and 7A, which mimic its phosphorylation by CKII and lack of phosphorylation by Pho85-Pho80, caused an increase in triacylglycerol content and lipid droplet number in cells expressing the Nem1-Spo7 phosphatase complex.

Phosphorylation regulates the ubiquitin-independent degradation of yeast Pah1 phosphatidate phosphatase by the 20S proteasome.

Saccharomyces cerevisiae Pah1 phosphatidate phosphatase, which catalyzes the conversion of phosphatidate to diacylglycerol for triacylglycerol synthesis and simultaneously controls phosphatidate levels for phospholipid synthesis, is subject to the proteasome-mediated degradation in the stationary phase of growth. In this study, we examined the mechanism for its degradation using purified Pah1 and isolated proteasomes. Pah1 expressed in S. cerevisiae or Escherichia coli was not degraded by the 26S proteasome, but by its catalytic 20S core particle, indicating that its degradation is ubiquitin-independent. The degradation of Pah1 by the 20S proteasome was dependent on time and proteasome concentration at the pH optimum of 7.0. The 20S proteasomal degradation was conserved for human lipin 1 phosphatidate phosphatase. The degradation analysis using Pah1 truncations and its fusion with GFP indicated that proteolysis initiates at the N- and C-terminal unfolded regions. The folded region of Pah1, in particular the haloacid dehalogenase-like domain containing the DIDGT catalytic sequence, was resistant to the proteasomal degradation. The structural change of Pah1, as reflected by electrophoretic mobility shift, occurs through its phosphorylation by Pho85-Pho80, and the phosphorylation sites are located within its N- and C-terminal unfolded regions. Phosphorylation of Pah1 by Pho85-Pho80 inhibited its degradation, extending its half-life by ∼2-fold. The dephosphorylation of endogenously phosphorylated Pah1 by the Nem1-Spo7 protein phosphatase, which is highly specific for the sites phosphorylated by Pho85-Pho80, stimulated the 20S proteasomal degradation and reduced its half-life by 2.6-fold. These results indicate that the proteolysis of Pah1 by the 20S proteasome is controlled by its phosphorylation state.

Yeast Pah1p phosphatidate phosphatase is regulated by proteasome-mediated degradation.

Yeast PAH1-encoded phosphatidate phosphatase is the enzyme responsible for the production of the diacylglycerol used for the synthesis of triacylglycerol that accumulates in the stationary phase of growth. Paradoxically, the growth phase-mediated inductions of PAH1 and phosphatidate phosphatase activity do not correlate with the amount of Pah1p; enzyme abundance declined in a growth phase-dependent manner. Pah1p from exponential phase cells was a relatively stable protein, and its abundance was not affected by incubation with an extract from stationary phase cells. Recombinant Pah1p was degraded upon incubation with the 100,000 × g pellet fraction of stationary phase cells, although the enzyme was stable when incubated with the same fraction of exponential phase cells. MG132, an inhibitor of proteasome function, prevented degradation of the recombinant enzyme. Endogenously expressed and plasmid-mediated overexpressed levels of Pah1p were more abundant in the stationary phase of cells treated with MG132. Pah1p was stabilized in mutants with impaired proteasome (rpn4Δ, blm10Δ, ump1Δ, and pre1 pre2) and ubiquitination (hrd1Δ, ubc4Δ, ubc7Δ, ubc8Δ, and doa4Δ) functions. The pre1 pre2 mutations that eliminate nearly all chymotrypsin-like activity of the 20 S proteasome had the greatest stabilizing effect on enzyme levels. Taken together, these results supported the conclusion that Pah1p is subject to proteasome-mediated degradation in the stationary phase. That Pah1p abundance was stabilized in pah1Δ mutant cells expressing catalytically inactive forms of Pah1p and dgk1Δ mutant cells with induced expression of DGK1-encoded diacylglycerol kinase indicated that alteration in phosphatidate and/or diacylglycerol levels might be the signal that triggers Pah1p degradation.

Combination of lipid metabolism alterations and their sensitivity to inflammatory cytokines in human lipin-1-deficient myoblasts.

Lipin-1 deficiency is associated with massive rhabdomyolysis episodes in humans, precipitated by febrile illnesses. Despite well-known roles of lipin-1 in lipid biosynthesis and transcriptional regulation, the pathogenic mechanisms leading to rhabdomyolysis remain unknown. Here we show that primary myoblasts from lipin-1-deficient patients exhibit a dramatic decrease in LPIN1 expression and phosphatidic acid phosphatase 1 activity, and a significant accumulation of lipid droplets (LD). The expression levels of LPIN1-target genes [peroxisome proliferator-activated receptors delta and alpha (PPARδ, PPARα), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), acyl-coenzyme A dehydrogenase, very long (ACADVL), carnitine palmitoyltransferase IB and 2 (CPT1B and CPT2)] were not affected while lipin-2 protein level, a closely related member of the family, was increased. Microarray analysis of patients' myotubes identified 19 down-regulated and 51 up-regulated genes, indicating pleiotropic effects of lipin-1 deficiency. Special attention was paid to the up-regulated ACACB (acetyl-CoA carboxylase beta), a key enzyme in the fatty acid synthesis/oxidation balance. We demonstrated that overexpression of ACACB was associated with free fatty acid accumulation in patients' myoblasts whereas malonyl-carnitine (as a measure of malonyl-CoA) and CPT1 activity were in the normal range in basal conditions accordingly to the normal daily activity reported by the patients. Remarkably ACACB invalidation in patients' myoblasts decreased LD number and size while LPIN1 invalidation in controls induced LD accumulation. Further, pro-inflammatory treatments tumor necrosis factor alpha+Interleukin-1beta(TNF1α+IL-1ß) designed to mimic febrile illness, resulted in increased malonyl-carnitine levels, reduced CPT1 activity and enhanced LD accumulation, a phenomenon reversed by dexamethasone and TNFα or IL-1ß inhibitors. Our data suggest that the pathogenic mechanism of rhabdomyolysis in lipin-1-deficient patients combines the predisposing constitutive impairment of lipid metabolism and its exacerbation by pro-inflammatory cytokines.

Molecular characterization of a phenylalanine ammonia-lyase gene (BoPAL1) from Bambusa oldhamii.

Phenylalanine ammonia-lyase is the first enzyme of general phenylpropanoid pathway. A PAL gene, designated as BoPAL1, was cloned from a Bambusa oldhamii cDNA library. The open reading frame of BoPAL1 was 2,139 bp in size and predicted to encode a 712-amino acid polypeptide. BoPAL1 was the first intronless PAL gene found in angiosperm plant. Several putative cis-acting elements such as P box, GT-1motif, and SOLIPs involved in light responsiveness were found in the 5'-flanking sequence of BoPAL1 which was obtained by TAIL-PCR method. Recombinant BoPAL1 protein expressed in Pichia pastoris was active. The optimum temperature and pH for BoPAL1 activity was 50°C and 9.0, respectively. The molecular mass of recombinant BoPAL1 was estimated as 323 kDa using gel filtration chromatography and the molecular mass of full-length BoPAL was about 80 kDa, indicating that BoPAL1 presents as a homotetramer. The Km and kcat values of BoPAL1 for L-Phe were 1.01 mM and 10.11 s(-1), respectively. The recombinant protein had similar biochemical properties with PALs reported in other plants.

Cloning, expression, site-directed mutagenesis and immunolocalization of phenylalanine ammonia-lyase in Bambusa oldhamii.

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) from green bamboo was isolated and cloned from the shell of Bambusa oldhamii. The K(m) of bamboo shell PAL for L-Phe was 476 µM, and the molecular mass of native PAL was estimated as 275 kDa and the molecular mass of a subunit was about 76 kDa, indicating that PAL from bamboo also exists as a tetramer. The optimum temperature for PAL activity was 50°C and the optimal pH 9.0. The identity of the purified bamboo shell PAL was confirmed using Q-TOF tandem MS/MS de novo sequencing. Four PAL genes, designated as BoPAL1 to BoPAL4, were cloned from B. oldhamii. The open reading frames of BoPAL3 and BoPAL4 were 2142 and 2106 bp in size, respectively: BoPAL2-4 contained one intron and two exons, but no intron was found in BoPAL1. BoPAL4 expressed in Escherichia coli possessed both PAL and tyrosine ammonia-lyase activities. While recombinant wild-type PAL proteins had similar biochemical properties to the native bamboo shell PAL, both site-directed mutagenesis of BoPAL1 F133H and BoPAL2 F134H, respectively, showed decreased k(cat)/K(m) values toward L-Phe, whereas BoPAL2 F134H showed a slightly increased k(cat)/K(m) value toward L-Tyr. These data suggest other residues largely control Phe/Tyr substrate specificity. An antibody raised against the purified shell PAL was generated for histochemical studies. In bamboo shell and branch shoots, PAL was localized primarily in sclerenchyma cells.

Cloning and expression of a phenylalanine ammonia-lyase gene (BoPAL2) from Bambusa oldhamii in Escherichia coli and Pichia pastoris.

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) is the first committed enzyme of phenylpropanoid pathway. A PAL gene, designated as BoPAL2, was cloned from a Bambusa oldhamii cDNA library. The open reading frame of BoPAL2 was 2142bp in size encoding a 713-amino acid polypeptide. BoPAL2 was heterologous expressed in Escherichia coli and Pichia pastoris. The recombinant proteins were exhibited PAL and tyrosine ammonia-lyase activities. The recombinant BoPAL2 had a subunit mass of 80kDa and existed as a homotetramer. The optimum temperature and pH of BoPAL2 were 50-60 degrees C and 8.5-9.0, respectively. The K(m) and k(cat) values of BoPAL2 expressed in E. coli were 250microM and 10.12s(-1). The K(m) and k(cat) values of BoPAL2 expressed in P. pastoris were 331microM and 16.04s(-1). The recombinant proteins had similar biochemical properties and kinetic parameters with PALs reported in other plants.