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At least 19 recordsLinked to original sources
PubMed1976

Histidine ammonia-lyase from rat liver. Purification, properties, and inhibition by substrate analogues.

Histidine ammonia-lyase (EC 4.3.1.3) from rat liver was purified more than 250-fold to near homogeneity. Electrophoretic determinations indicated a native molecular weight of approximately 200,000. The enzyme has a pH optimum of approximately pH 8.5. The minimum Km for L-histidine was 0.5 mM at pH 9.0. The Michaelis constant in the physiological pH range was, however, more than 2.0 mM. D-alpha-hydrazinoimidazolylpropionic acid was found to be a potent competitive inhibitor of liver histidine ammonia-lyase (Kis=75 muM); the L enantiomer of this compound was less effective in this regard. The enzyme was also inhibited competitively by L-histidine hydroxamate (Kis=0.4 mM), and to a lesser extent by L-histidinol, D-histidine, and glycine. Failure of a wide variety of other histidine analogues to inhibit the enzyme substantially indicates high specificity of the active site for L-histidine. No alternate substrates were identified for the enzyme. DL-alpha-Hydrazinophenylpropionic acid, the alpha-hydrzino analogue of phenylalanine, was similarly shown to be a very potent competitive inhibitor of a mechanistically similar L-phenylalanine ammonia-lyase purified from Rhodotorula glutinis. The properties of histidine ammonia-lyase from rat liver differ significantly from those of the enzyme from Pseudomonas fluorescens which has been studied most extensively to date.

Ammonia-Lyases↗
PubMed1976

Studies on the production and assessment of experimental histidinemia in the rat.

Intraperitoneal administration to rats of D- or DL-alpha-hydrazinoimidazolylpropionic acid was found to produce a substantial inactivation of hepatic histidine ammonia-lyase (EC 4.3.1.3) in vivo. Proportional to this loss in enzyme activity was an impairment of the ability of treated rats to oxidize L-[ring-2-14C] histidine to 14CO2. Rats in which hepatic histidine ammonia-lyase activity was either depressed by DL-hydrazinoimidazolylproprionic acid injection or elevated by feeding a high protein diet displayed proportionately altered rates of 3H2O release into plasma water following L-[3-3H] histidine administration. Plasma L-histidine clearance following loading with this amino acid was similarly affected by these treatments. Administration of DL-alphal-hydrazinoimisazolylproprionic acid to rats was also found to inactivate non-specifically pyridoxal 5-phosphate enzymes in vivo; pyridoxine injection was found to reverse the DL-alpha-hydrazinoimidazolylproprionic acid-induced inactivation of hepatic aspartate aminotransferase (EC 2.6.1.1) in vivo, but not that of hepatic histidine ammonia-lyase. These findings demonstrate that histidine ammonia-lyase is the rate-limiting factor in L-histidine degradation in the rat. The potential usefulness of DL-hydrazinoimidazolylproprionic acid in the production of an animal model for histidinemia (hereditary histidine ammonia-lyase deficiency) is discussed.

Ammonia-Lyases↗
PubMed2026

Evolution and Expression Divergence of Legume PAL Genes Suggest Associations with Drought Response and Root Nodule Development.

Comparative genomic analyses provide insight into the mechanisms underlying gene-family evolution and crop adaptation. Here, we used the legume phenylalanine ammonia-lyase (PAL) gene family as a model and integrated pan-genomic, phylogenetic, molecular evolutionary, duplication-mode, and transcriptomic analyses, while developing GFtool for gene family identification. Across 45 genomes, we identified 302 PAL genes and classified them into five Groups. Groups 1-3 represented ancient lineages shared with outgroups, whereas Groups 4 and 5 were legume-specific. Molecular-clock analyses placed the divergence of Group 2 near the Paleocene-Eocene transition, while Groups 4 and 5 diversified from the middle Eocene to the early Oligocene. WGD/segmental duplication broadly contributed to PAL copy-number expansion, whereas tandem duplication was enriched in Group 5 of Papilionoideae. Group 2 genes showed drought-induced expression, whereas Group 5 genes were associated with early root nodule development. GFtool provides a scalable framework for gene-family studies.

Fabaceae↗
PubMed2026

Genome-Wide Identification of the PAL Gene Family in Idesia polycarpa and Transcriptomic Responses to Botryosphaeria dothidea Infection.

Idesia polycarpa is a woody oil tree threatened by stem canker caused by Botryosphaeria dothidea, yet the organization and infection-responsive behavior of its phenylalanine ammonia-lyase (PAL) gene family remain poorly understood. Here, we identified five IpPAL genes and characterized their phylogenetic relationships, conserved features, duplication patterns, promoter cis-elements, and infection-associated expression profiles. Segmental and tandem duplication contributed to IpPAL family evolution, and all duplicated pairs showed Ka/Ks ratios below 1, consistent with purifying selection. RNA sequencing (RNA-seq) of contrasting Chengdu and Zhangjiajie provenances revealed distinct temporal responses. In Chengdu, IpPAL2-IpPAL4 were significantly upregulated at 24 h after inoculation, whereas all five genes were upregulated at 96 h. In Zhangjiajie, all five IpPAL genes were significantly upregulated at 24 h, while IpPAL2-IpPAL5 remained upregulated at 96 h. No IpPAL gene met the differential-expression criteria between provenances under mock conditions or at 24 h; at 96 h, IpPAL1 and IpPAL3 were lower and IpPAL5 was higher in Zhangjiajie than in Chengdu. Scanning electron microscopy (SEM) provided complementary qualitative evidence of provenance-associated tissue responses. These findings demonstrate time- and gene-specific IpPAL responses to B. dothidea and identify candidate genes for further functional analysis.

Ascomycota↗
PubMed2025

Dual genetic loci and flavonoid metabolism orchestrate fruiting body coloration in Flammulina filiformis: a multi-omic roadmap for fungal pigmentation.

BACKGROUND: The fruiting bodies of macrofungi exhibit diverse coloration, traditionally attributed to melanin and carotenoid biosynthesis. This study is the first to reveal that flavonoids, rather than these classical pigments, are the predominant contributors to yellow pigmentation in the Flammulina filiformis. OBJECTIVE: To uncover the genetic basis and key regulatory genes involved in pigment formation in F. filiformis fruiting bodies, and to establish a model framework for studying color genetics in macrofungi. METHODS: Metabolomic profiling was conducted on yellow and white F. filiformis fruiting bodies to identify key pigment components. A segregating population was constructed, followed by integrated multi-omics analyses-including bulk segregant analysis (BSA), genome-wide association study (GWAS), and transcriptomics-to map regulatory loci and candidate genes. Functional roles were validated via genetic transformation and protein structural modeling. RESULTS: Flavonoid accumulation was identified as the biochemical hallmark of pigmented fruiting bodies. Genetic analysis revealed a dual regulatory mechanism: a qualitative locus governing pigmentation presence and a quantitative trait determining color intensity. Combined BSA and GWAS pinpointed a major locus, Ffcrs, within a recombination-suppressed region. Transcriptomic analysis identified two key regulators, Ffakr (a transcriptional activator) and Ffpal (encoding phenylalanine ammonia-lyase). Functional verification via transformation, structural modeling, and metabolite profiling in transgenic lines confirmed their essential roles in flavonoid biosynthesis and pigmentation. CONCLUSION: This study uncovers a flavonoid-based pigmentation mechanism in F. filiformis and elucidates a complex genetic architecture shaped by both qualitative and quantitative loci, providing a new paradigm for understanding pigment formation in macrofungi. The identified regulatory factors establish a molecular foundation for the precise manipulation of economically important pigmentation traits in edible mushroom.

Flavonoids↗
PubMed2026

Biocontrol Potential and Mechanism of Endophytic Bacillus velezensis WSR1 Against Rubber Tree Anthracnose.

Fungal leaf anthracnose, caused by Colletotrichum species, is a major leaf disease of rubber trees, significantly reducing global natural rubber yields. To explore sustainable and safe biological control strategies, eight bacterial strains were isolated from rubber tree tissues, demonstrating antagonistic activity against Colletotrichum pathogens (C. siamense and C. australisinense). Among these, WSR1 exhibited the most pronounced antifungal effect, with inhibition rates of 87.64 and 89.03% against C. siamense and C. australisinense, respectively. Genomic analysis identified WSR1 as Bacillus velezensis. In pot experiments, WSR1 exhibited preventive efficacy of 77.24 and 73.42% for C. siamense- and C. australisinense-induced anthracnose, respectively, with therapeutic efficacy of 42.28 and 45.57%. WSR1 compromised the integrity of the cell walls and membranes of both C. siamense and C. australisinense, while inducing reactive oxygen species accumulation within the hyphae. Additionally, WSR1 enhanced rubber tree resistance to anthracnose by activating defense-related enzymes, including phenylalanine ammonia-lyase, polyphenol oxidase, and peroxidase. Plate assays and genomic analysis revealed that WSR1 secretes fungal cell wall-degrading enzymes (cellulases, pectinases, and proteases) and siderophores. Furthermore, liquid chromatography-mass spectrometry and gene cluster analysis confirmed the synthesis of antagonistic secondary metabolites, such as surfactin, macrolactin H, and fengycin. This study represents the first identification of B. velezensis as a potential biocontrol agent against rubber tree anthracnose, offering a promising candidate for the eco-friendly management of rubber tree diseases.

C. australisinense↗
PubMed2026

Rapid transcriptional reprogramming underlies Fusarium wilt resistance in strawberry: insights from comparative physiological and transcriptomic analyses.

INTRODUCTION: Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae (Fof) severely constrains strawberry production, yet the underlying resistance mechanisms remain unclear. METHODS: A total of 64 strawberry germplasm accessions were evaluated for Fusarium wilt resistance. Integrated physiological and transcriptomic analyses were subsequently performed using the highly resistant cultivar 'Akihime' (ZJ) and the highly susceptible cultivar 'Ning Yu' (NY). RESULTS: Resistant resources were abundant, particularly among wild strawberry accessions. Compared with NY, ZJ exhibited higher soluble sugar accumulation, reduced oxidative damage, and increased peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities. Transcriptomic analyses revealed distinct temporal response patterns: ZJ underwent rapid and extensive transcriptional reprogramming at 24 h post-inoculation, whereas NY showed limited early responses but pronounced changes at 120 h. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses indicated that the early response of ZJ was mainly associated with stress-related processes, jasmonic acid-mediated signaling, transmembrane transport, plant-pathogen interaction, mitogen-activated protein kinase (MAPK) signaling, glutathione metabolism, plant hormone signal transduction, and secondary metabolism. Quantitative real-time polymerase chain reaction (qRT-PCR) validation supported the RNA-seq results and identified candidate genes associated with pathogen recognition, signaling, redox regulation, and protein homeostasis. DISCUSSION: These results indicate that rapid early immune activation and coordinated physiological and metabolic reprogramming are closely associated with strawberry resistance to Fof and provide useful germplasm and candidate genes for future functional validation and resistance breeding.

Fusarium oxysporum f. sp. fragariae↗
PubMed1976

The effect of nitrogen limitation on catabolite repression of amidase, histidase and urocanase in Pseudomonas aeruginosa.

In Pseudomonas aeruginosa, the synthesis of histidase, urocanase and amidase is severly repressed when succinate is added to a culture growing in pyruvate + ammonium salts medium. When growth is nitrogen-limited, catabolite repression by succinate of histidase and urocanase synthesis does not occur but succinate repression of amidase synthesis persists. Amidase synthesis is not regulated in the same way as histidase synthesis by the availability of other nitrogen compounds for growth. Growth of P. aeruginosa strain PACI in succinate + histidine media is nitrogen-limited since this strain is defective in a histidine transport system. When methyl-ammonium chloride is added to succinate + histidine media, growth inhibition occurs. Mutants isolated from succinate + histidine + methylammonium chloride plates were found to be resistant to catabolite repression by succinate even in ammonium salts media. It is suggested that the hut genes of P. aeruginosa may be regulated in the same way as in Klebsiella aerogenes, by induction by urocanate and activation by either the cyclic AMP-dependent activator protein or by glutamine synthetase.

Amidohydrolases↗
PubMed1976

Regulation of histidase synthesis in intergeneric hybrids of enteric bacteria.

Regulation of the expression of the histidase coded by hutk of Klebsiella aerogenes in Salmonella typhimurium and in Escherichia coli and of the expression of the histidase coded by huts of S. typhimurium in E. coli was investigated. The hutk histidase was found to be sensitive to catabolite repression in K. aerogenes and in E. coli, but insensitive to catabolite repression in S. typhimurium; huts histidase has previously been shown to be catabolite sensitive in all three organisms. The expression of both hutk and huts histidase in E. coli was activated by nitrogen starvation. Apparently, the glutamine synthetase of E. coli may activate the formation of some glutamate- and ammonia-producing enzymes.

Ammonia-Lyases↗
PubMed1976

Regulation of enzyme formation in Klebsiella aerogenes by episomal glutamine synthetase of Escherichia coli.

We studied the physiology of cells of Klebsiella aerogenes containing the structural gene for glutamine synthetase (glnA) of Escherichia coli on an episome. The E. coli glutamine synthetase functioned in cells of K. aerogenes in a manner similar to that of the K. aerogenes enzyme: it allowed the level of histidase to increase and that of glutamate dehydrogenase to decrease during nitrogen-limited growth. The phenotype of mutations in the glnA site was restored to normal by the introduction of the episomal glnA+ gene. These results are consistent with the hypothesis that glutamine synthetase regulates the function of its own structural gene.

Ammonia-Lyases↗
PubMed1976

Biosynthesis of uroporphyrinogens from porphobilinogen: mechanism and the nature of the process.

The enzymic self-polymerization of prophobilinogen gives rise to the cyclic tetrapyrroles uroporphyrinogen III and uroporphyrinogen I. The former is the precursor of all the natural porphyrins and chlorins. The formation of uroporphyrinogen III is catalysed by a dual enzymic system, porphobilinogen deaminase and uroporphyrinogen III cosynthase. Deaminase polymerizes four porphobilinogen units on the enzymic surface, without liberation of free intermediates into the reaction medium, and forms uroporphyrinogen I. Cosynthase enters into association with the deaminase, and acts as a 'specifier protein' of the latter, changing the mode of porphobilinogen condensation on the enzymic surface. The association is independent of the presence of substrate. While deaminase catalyses the head-to-tail condensation of the porphobilinogen units, the association deaminase-cosynthase catalyses the head-to-head condensation of the same units. As a result different enzyme-bound dipyrrylmethanes are formed form the beginning of the process, and this can be demonstrated by using synthetic dipyrrylmethanes and tripyrranes.

Ammonia-Lyases↗
PubMed1975

Expression of the hut operons of Salmonella typhimurium in Klebsiella aerogenes and in Escherichia coli.

The normal hut (histidine utilization) operons, as well as those with mutations affecting the regulation of their expression, of Salmonella typhimurium were introduced on an F' episome into cells of S. typhimurium and Klebsiella aerogenes whose chromosomal hut genes had been deleted and into cells of Escherichia coli, whose chromosome does not carry hut genes. The episomal hut operons respond in a manner very similar to induction and catabolite repression in all three organisms. The small differences found reflect both different abilities to take up inducers from the medium and different degrees of catabolite repression exerted by glucose.

Amidohydrolases↗
PubMed1975

Regulation of the hut operons of Salmonella typhimurium and Klebsiella aerogenes by the heterologous hut repressors.

In merodiploid strains of Klebsiella aerogenes with chromosomal hut genes of K. aerogenes and episomal hut genes of Salmonella typhimurium, the repressor of either species can regulate the hut operons of the other species. The repression exerted by the homologous repressor on the left-hand hut operon is, in both organisms, stronger than that exerted by the heterologous repressor.

Cell-Free System↗
PubMed1976

Deoxyribonucleic acid-binding studies on the hut repressor and mutant forms of the hut repressor of Salmonella typhimurium.

In Salmonella typhimurium the genes coding for the enzymes of histidine utilization (hut) are clustered in two adjacent operons, hutMIGC and hut(P,R,Q)UH. A single repressor, the product of the C gene, regulates both operons by binding at two operator sites, one near M and one in (P,R,Q). The deoxyribonucleic acid (DNA)-binding activity of the repressor was measured using DNA's containing separate operators. The repressor had greater activity when assayed using DNA containing the operator of the (P,R,Q)UH operon than when assayed using DNA containing the operator of the MIGC operon. The binding to either operator was absent in the presence of the inducer, urocanate. The DNA-binding activities were also determined for two super-repressors. The super-repressors had altered DNA-binding properties, although the self-regulated nature of the repressors complicated the analysis of the results. A purfication procedure for the wild-type repressor is presented. The purified repressor was somewhat unstable, and additional experiments using it were not performed.

Amidohydrolases↗
PubMedDate not supplied

[The effect of lipids from typhoid endotoxin on the activity of some liver enzymes].

Sublethal doses of typhoid endotoxin distinctly increased the activities of glutamate dehydrogenase and histidine ammonium lyase in liver tissue of mice within 3 hrs and the tyrosine transaminase activity within 6 hrs after a single intraperitoneal administration. Within 24 hrs normalzation of these enzyme activities and a decrease in the urocaninase activity were observed in liver tissue. Lipid A, obtained from the endotoxin, activated glutamate dehydrogenase and histidine ammonium lyase, inhibited urocaninase but did not affect the tyrosine transaminase activity. Lipid B, isolated by a non-hydrolytic method, showed even wore distinct capacity to activate glutamate dehydrogenase and histidine ammonium lyase, but did not alter the activities of tyrosine transaminase and urocaninase in liver tissue.

Animals↗
PubMed1976

L-Asparaginase of Klebsiella aerogenes. Activation of its synthesis by glutamine synthetase.

An L-asparaginase has been purified some 250-fold from extracts of Klebsiella aerogenes to near homogeneity. The enzyme has a molecular weight of 141,000 as measured by gel filtration and appears to consist of four subunits of molecular weight 37,000. The enzyme has high affinity for L-asparagine, with a Km below 10(-5) M, and hydrolyzes glutamine at a 20-fold lower rate, with a Km of 10(-3) M. Interestingly, the enzyme exhibits marked gamma-glutamyltransferase activity but comparatively little beta-aspartyl-transferase activity. A mutant strain lacking this asparaginase has been isolated and grows at 1/2 to 1/3 the rate of the parent strain when asparagine is provided in the medium as the sole source of nitrogen. This strain grows as well as the wild type when the medium is supplemented with histidine or ammonia. Glutamine synthetase activates the formation of L-asparaginase. Mutants lacking glutamine synthetase fail to produce the asparaginase, and mutants with a high constitutive level of glutamine synthetase also contain the asparaginase at a high level. Thus, the formation of asparaginase is regulated in parallel with that of other enzymes capable of supplying the cell with ammonia or glutamate, such as histidase and proline oxidase. Formation of the asparaginase does not require induction by asparaginase and is not subject to catabolite repression.

Alkaline Phosphatase↗
PubMed1976

[Resistance to levomycetin and activity of several enzymes in Escherichia coli and the agent of plague].

The authors compared the activity of acetyl-CoA-synthetase and of the enzymes belonging to the group of asparaginic acid in levomycetin sensitive and resistant strains of Y. pestis and E. coli. There were revealed marked differences in the activity of aspartase, fumarase, synthetase and desamidase of L-asparagin, and also of the enzyme activated by acetate in the E. coli strains with plasmide resistance. Transmission of R-factor to the pestis was accompanied by decomposition of L-asparadein, formation of AC-CoA. At the same time transformation of L-asparaginic acid catalyzed by aspartase remained on the same low level in the sensitive pestis cultures and their variants with the R-factor. When the resistance was controlled by chromosomal resistance markers, the activity of the enzymes providing formation of L-asparagic acid, its amide and L-malic acid showed no significant change. In chromosomal type of resistance in the mutants of pestis and E. coli the acetyl-CoA-synthetase reaction was as a rule somewhat increased.

Acetate-CoA Ligase↗