Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.5.1.4 (deaminase)
5,113 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1-Aminocyclopropane-1-carboxylate synthase (ACC synthase, EC 4.4.1. 14) catalyzes the rate-limiting step in the ethylene biosynthetic pathway in plants. To determine the amino acid residues critical for the structure and function of this enzyme, the tomato Le-ACS2 isoenzyme has been subjected to both site-directed and PCR random mutagenesis. Mutant ACC synthases with reduced enzyme activity have been selected by using a genetic screen based on the functional complementation of an Escherichia coli Ile auxotroph that has been engineered to express ACC deaminase from Pseudomonas sp. The DNA sequence of almost 1,000 clones has been determined, and 334 single missense mutations have been selected for analysis. We have identified three classes of mutants based on their activity and expression in E. coli. Class I and II mutants have the same level of protein expression as the wild type, but their enzyme activity is reduced to 0-5% and 5-50%, respectively. Class III mutants have neither activity nor detectable protein expression. The inactive mutations are clustered in regions that are highly conserved among various ACC synthases. This library of mutants will facilitate the elucidation of structure-function relationships of this regulatory enzyme.
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PMID:Random mutagenesis of 1-aminocyclopropane-1-carboxylate synthase: a key enzyme in ethylene biosynthesis. 970 55

The ACC deaminase gene (acdS) from Enterobacter cloacae UW4 was replaced by homologous recombination with the acdS gene with a tetracycline resistance gene inserted within the coding region. Upon characterization of this AcdS minus mutant, it was determined that both ACC deaminase activity and the ability to promote the elongation of canola roots under gnotobiotic conditions were greatly diminished. This result is consistent with a previously postulated model that suggests that a major mechanism utilized by plant growth-promoting bacteria involves the lowering of plant ethylene levels, and hence ethylene inhibition of root elongation, by bacterial ACC deaminase.
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PMID:An ACC deaminase minus mutant of Enterobacter cloacae UW4 no longer promotes root elongation. 1085 74

Analysis of the DNA sequence upstream of the previously isolated Enterobacter cloacae UW4 ACC deaminase gene (Shah et al. 1998) suggests that this segment contains several features that are thought to be involved in the transcriptional regulation of this gene. These features include half of a CRP (cAMP receptor protein) binding site, an FNR (fumarate-nitrate reduction) regulatory protein binding site, an LRP (leucine responsive regulatory protein) binding site, and an LRP-like protein coding region. ACC deaminase activity was measured following growth of either various Escherichia coli strains carrying a plasmid that contained the Enterobacter cloacae UW4 ACC deaminase gene, or of Enterobacter cloacae UW4. Variables that were compared include aerobic versus anaerobic conditions, the presence and absence of ACC in the growth medium, addition of leucine to the medium, and bacterial strains that did or did not contain either lrp or fnr genes. The data reported are consistent with the involvement of most, if not all, of the above mentioned potential regulatory regions in the expression of ACC deaminase.
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PMID:Identification of DNA sequences that regulate the expression of the Enterobacter cloacae UW4 1-aminocyclopropane-1-carboxylic acid deaminase gene. 1114 8

The sequence has been determined of 80 888 bp of contiguous subtelomeric DNA, including the isp5 gene, from the right arm of chromosome I of Schizosaccharomyces pombe; 27 open reading frames (ORFs) longer than 100 codons are present, giving a density of one gene per 3.0 kb. Seven of the predicted proteins are members of the major facilitator superfamily (MFS) of transport proteins, including four amino acid permease homologues, bringing this family of amino acid permease sequences to 17 in Sz. pombe, and a phylogenetic analysis is presented. Also encoded is an allantoate permease homologue, a sulphate permease homologue and a probable urea active transporter. Predicted non-membrane proteins include a 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase), a class III aminotransferase, serine acetyltransferase, protein-L-isoaspartate O-methyltransferase, alpha-glucosidase, alpha-galactosidase, esterase/lipase, oxidoreductase of the short-chain dehydrogenase/reductase (SDR) family, aldehyde dehydrogenase, formamidase, amidase, flavohaemoprotein, a putative translation initiation inhibitor and a protein with similarity to a filamentous fungal conidiation-specific protein. The remaining six ORFs are likely to encode proteins, either because they have sequence similarity with hypothetical proteins or because they are known to be transcribed. Introns are scarce in the sequenced region: only three ORFs contain introns, with only one having multiple introns. The sequenced region also contains a single Tf1 transposon long terminal repeat (LTR). The sequence is derived from cosmid clones c869, c922 and c1039 and has been submitted to the EMBL database under entries SPAC869 (Accession No. AL132779), SPAC922 (AL133522) and SPAC1039 (AL133521).
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PMID:Subtelomeric sequence from the right arm of Schizosaccharomyces pombe chromosome I contains seven permease genes. 1122 45

The ACC deaminase structural gene (acdS) from Enterobacter cloacae UW4 was cloned in the broad host range plasmid pRK415 under the control of the lac promoter and transferred into Azospirillum brasilense Cd and Sp245. A. brasilenseCd and Sp245 transformants showed high ACC deaminase activity, similar to that observed in Enterobacter cloacae UW4. The expression of ACC deaminase improved the existing growth promoting activity of Azospirillum. The roots of tomato and canola seedlings were significantly longer in plants inoculated with A. brasilense Cd transformants than those in plants inoculated with the nontransformed strains of the same bacterium. In the case of wheat seedlings, inoculation with A. brasilense Cd transformants did not promote root growth. The difference in plant response (canola and tomato versus wheat) is attributed to the greater sensitivity of canola and tomato plants to ethylene as compared to wheat plants.
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PMID:Expression of the ACC Deaminase Gene fromEnterobacter cloacae UW4 in Azospirillum brasilense. 1139 66

It has been reported that PGPB, containing ACC deaminase, can cleave the plant ethylene precursor ACC and thereby lower ethylene concentration in a developing or stressed plant, protecting it against the deleterious effects of stress ethylene and facilitating the formation of longer roots. In a previous work we have demonstrated expression of the ACC deaminase gene ( acdS) from Enterobacter cloacae UW4 under the control of the lac promoter in Azospirillum brasilense Cd. With the inference that a construct including the ACC deaminase gene under the control of a constitutive promoter weaker than the lac promoter might impose less metabolic load on Azospirillum and improve its fitness, it was decided to clone acdS under the control of a tetracycline resistance gene promoter. The ACC deaminase structural gene was fused to the Tet(r) gene promoter by overlap extension using PCR, cloned in pRK415, and transferred into A. brasilense Cd. The resulting transformants showed lower ACC deaminase activity than those with the lac promoter controlled acdS gene. However, acdS under the control of the Tet(r) gene promoter imposed lesser metabolic load on Azospirillum brasilense Cd. The result was significantly increased IAA synthesis and greater bacterial growth rate, as well as increased ability to survive on the surface of tomato leaves and to promote the growth of tomato seedlings.
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PMID:Transformation of Azospirillum brasilense Cd with an ACC deaminase gene from enterobacter cloacae UW4 fused to the Tet r gene promoter improves its fitness and plant growth promoting ability. 1273 73

1-Aminocyclopropane-l-carboxylate deaminase (ACCD) is a pyridoxal 5/-phosphate dependent enzyme that shows deaminase activity toward ACC, a precursor of plant hormone ethylene. ACCD from some soil bacteria has been reported to be able to break the cyclopropane ring of ACC to yield a-ketobutyrate and ammonia. We reported the crystal structure of ACCD from the yeast Hansenula saturnus in the absence/presence of substrate ACC, and proposed its ingenious reaction mechanisms. In order to study the enzyme further, we overexpressed the ACCD homologue protein (phAHP) from the fully decoded hyperthermophilic archearon, Pyrococcus horikoshii OT3. However, phAHP does not show ACCD activity at high temperature as well as at room temperature, though it has significant sequence similarity. Instead of ACCD activity, the GC-MS analysis and enzymatic method show that phAHP has deaminase activity toward L and D-serine. Here, we present the crystal structures of the native and ACC-complexed phAHP. The overall topology of the phAHP structure is very similar to that of ACCD; however, critical differences were observed around the active site. Here, the differences of enzymatic activity between phAHP and ACCD are discussed based on the structural differences of these two proteins. We suggest that the catalytic disagreement between these two enzymes comes from the difference of the residues near the pyridine ring of pyridoxal 5'-phosphate (PLP), not the difference of the catalytic residues themselves. We also propose a condition necessary in the primary sequence to have ACCD activity.
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PMID:Structural and enzymatic properties of 1-aminocyclopropane-1-carboxylate deaminase homologue from Pyrococcus horikoshii. 1532 14

Although plant growth-promoting rhizobacteria (PGPR) have been reported to influence plant growth, yield and nutrient uptake by an array of mechanisms, the specific traits by which PGPR promote plant growth, yield and nutrient uptake were limited to the expression of one or more of the traits expressed at a given environment of plant-microbe interaction. We selected nine different isolates of PGPR from a pool of 233 rhizobacterial isolates obtained from the peanut rhizosphere on the basis of ACC-deaminase activity. The nine isolates were selected, initially, on the basis of germinating seed bioassay in which the root length of the seedling was enhanced significantly over the untreated control. All the nine isolates were identified as Pseudomonas spp. Four of these isolates, viz. PGPR1, PGPR2, PGPR4 and PGPR7 (all fluorescent pseudomonads), were the best in producing siderophore and indole acetic acid (IAA). In addition to IAA and siderophore-producing attributes, Pseudomonas fluorescens PGPR1 also possessed the characters like tri-calcium phosphate solubilization, ammonification and inhibited Aspergillus niger and A. flavus in vitro. P. fluorescens PGPR2 differed from PGPR1 in the sense that it did not show ammonification. In addition to the traits exhibited by PGPR1, PGPR4 showed strong in vitro inhibition to Sclerotium rolfsii. The performances of these selected plant growth-promoting rhizobacterial isolates were repeatedly evaluated for 3 years in pot and field trials. Seed inoculation of these three isolates, viz. PGPR1, PGPR2 and PGPR4, resulted in a significantly higher pod yield than the control, in pots, during rainy and post-rainy seasons. The contents of nitrogen and phosphorus in soil, shoot and kernel were also enhanced significantly in treatments inoculated with these rhizobacterial isolates in pots during both the seasons. In the field trials, however, there was wide variation in the performance of the PGPR isolates in enhancing the growth and yield of peanut in different years. Plant growth-promoting fluorescent pseudomonad isolates, viz. PGPR1, PGPR2 and PGPR4, significantly enhanced pod yield (23-26%, 24-28% and 18-24%, respectively), haulm yield and nodule dry weight over the control in 3 years. Other attributes like root length, pod number, 100-kernel mass, shelling out-turn and nodule number were also enhanced. Seed bacterization with plant growth-promoting P. fluorescens isolates, viz. PGPR1, PGPR2 and PGPR4, suppressed the soil-borne fungal diseases like collar rot of peanut caused by A. niger and PGPR4 also suppressed stem rot caused by S. rolfsii. Studies on the growth patterns of PGPR isolates utilizing the seed leachate as the sole source of C and N indicated that PGPR4 isolate was the best in utilizing the seed leachate of peanut, cultivar JL24. Studies on the rhizosphere competence of the PGPR isolates, evaluated on the basis of spontaneous rifampicin resistance, indicated that PGPR7 was the best rhizoplane colonizer and PGPR1 was the best rhizosphere colonizer. Although the presence of growth-promoting traits in vitro does not guarantee that an isolate will be plant growth promoting in nature, results suggested that besides ACC-deaminase activity of the PGPR isolates, expression of one or more of the traits like suppression of phytopathogens, solubilization of tri-calcium phosphate, production of siderophore and/or nodulation promotion might have contributed to the enhancement of growth, yield and nutrient uptake of peanut.
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PMID:Growth promotion and yield enhancement of peanut (Arachis hypogaea L.) by application of plant growth-promoting rhizobacteria. 1564 84

We report the presence of ACC deaminase in Methylobacterium fujisawaense and its lowering of ethylene levels and promotion of root elongation in canola seedlings under gnotobiotic conditions. To test a part of the previous model proposed for ACC deaminase producing bacteria with Methylobacterium, ACC levels and various enzyme activities were monitored in canola. Lower amounts of ACC were present in the tissues of seeds treated with M. fujisawaense strains than in control seeds treated with MgSO(4). Though the increased activities of ACC synthase in the tissue extracts of the treated seedlings might be due to bacterial indole-3-acetic acid, the amount of ACC was reduced due to bacterial ACC deaminase activity. The activities of ACC oxidase, the enzyme catalyzing conversion of ACC to ethylene remained lower in M. fujisawaense treated seedlings. This consequently lowered the ethylene in plants and prevented ethylene inhibition of root elongation. Our results collectively suggest that Methylobacterium commonly found in soils, as well as on the surfaces of leaves, seeds, and in the rhizosphere of a wide variety of plants could be better exploited to promote plant growth.
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PMID:Regulation of ethylene levels in canola (Brassica campestris) by 1-aminocyclopropane-1-carboxylate deaminase-containing Methylobacterium fujisawaense. 1641 16

Burkholderia strains are promising candidates for biotechnological applications. Unfortunately, most of these strains belong to species of the Burkholderia cepacia complex (Bcc) involved in human infections, hampering potential applications. Novel diazotrophic Burkholderia species, phylogenetically distant from the Bcc species, have been discovered recently, but their environmental distribution and relevant features for agro-biotechnological applications are little known. In this work, the occurrence of N2-fixing Burkholderia species in the rhizospheres and rhizoplanes of tomato plants field grown in Mexico was assessed. The results revealed a high level of diversity of diazotrophic Burkholderia species, including B. unamae, B. xenovorans, B. tropica, and two other unknown species, one of them phylogenetically closely related to B. kururiensis. These N2-fixing Burkholderia species exhibited activities involved in bioremediation, plant growth promotion, or biological control in vitro. Remarkably, B. unamae and B. kururiensis grew with aromatic compounds (phenol and benzene) as carbon sources, and the presence of aromatic oxygenase genes was confirmed in both species. The rhizospheric and endophyte nature of B. unamae and its ability to degrade aromatic compounds suggest that it could be used in rhizoremediation and for improvement of phytoremediation. B. kururiensis and other Burkholderia sp. strains grew with toluene. B. unamae and B. xenovorans exhibited ACC (1-aminocyclopropane-1-carboxylic acid) deaminase activity, and the occurrence of acdS genes encoding ACC deaminase was confirmed. Mineral phosphate solubilization through organic acid production appears to be the mechanism used by most diazotrophic Burkholderia species, but in B. tropica, there presumably exists an additional unknown mechanism. Most of the diazotrophic Burkholderia species produced hydroxamate-type siderophores. Certainly, the N2-fixing Burkholderia species associated with plants have great potential for agro-biotechnological applications.
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PMID:The tomato rhizosphere, an environment rich in nitrogen-fixing Burkholderia species with capabilities of interest for agriculture and bioremediation. 1760 17


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