Disease relevance of ilvA

• This fragment does not contain ilvA, demonstrating the entirely different organization of the isoleucine biosynthesis genes in C. glutamicum from that in enterobacteria [1].
• Overlapping transcription and termination of the convergent ilvA and ilvY genes of Escherichia coli [2].
• IS2 activates the ilvA gene of Pseudomonas cepacia in Escherichia coli [3].
• Effects of an Escherichia coli ilvA mutant gene encoding feedback-resistant threonine deaminase on L-isoleucine production by Brevibacterium flavum [4].
• Expression of the Escherichia coli catabolic threonine dehydratase in Corynebacterium glutamicum and its effect on isoleucine production [5].

High impact information on ilvA

• ATP-driven proton pumping activity is lost with the substitution of lys, ile, val, or glu for arginine 210 [6].
• Based on the deduced amino acid sequences of the ilvA and ilvY genes, the translational termination codons for both genes are shown to be separated by 52 nucleotides [7].
• With the aim of obtaining regulatorily altered mutants of the threonine dehydratase of Corynebacterium glutamicum, amino acids were specifically exchanged and a new biological system of mutant selection was developed, based on the intoxication of Escherichia coli by ketobutyrate, which is the dehydratase reaction product [8].
• This provides further indications concerning the localization of the regulatory and catalytic domain of the threonine dehydratase [8].
• Threonine dehydratase is the key enzyme in L-isoleucine synthesis, since it is allosterically feedback-inhibited by L-isoleucine [8].

Chemical compound and disease context of ilvA

• From a collection of kanamycin-resistant mutants of Escherichia coli K-12 isolated by transposon Tn5 mutagenesis, we have identified a mutant that lacks functional biodegradative threonine dehydratase (EC 4.2.1.16) by direct enzyme assay and by the loss of cross-reacting material with affinity-purified antibodies against the purified enzyme [9].
• Control of biodegradative threonine dehydratase inducibility by cyclic AMP in energy-restricted Escherichia coli [10].
• (3) The structural similarity between rat Tyr AT and Escherichia coli aspartate AT was predicted, as well as (4) the structural similarity between TDH and the tryptophan synthase beta subunit [11].
• Intracellular alpha-ketobutyrate accumulates when valine is added to the medium because valine, which cannot be metabolized to HV by E. coli strain K-12, stimulates TD and inhibits acetolactate synthase [12].
• These results taken together tend to suggest that the biodegradative threonine dehydratase is the second gene in a polycistronic transcription unit constituting a novel operon (tdcABC) in E. coli implicated in anaerobic threonine metabolism [13].

Biological context of ilvA

• Strain MSR91 should be suitable for use in purification of the ilvA538 gene product, since enzyme synthesis is fully derepressed and the suppressor mutation is clearly not located within the ilvA gene [14].
• Genetic regulation of the ilvGMEDA cluster involves attenuation, internal promoters, internal Rho-dependent termination sites, a site of polarity in the ilvG pseudogene of the wild-type organism, and autoregulation by the ilvA gene product, the biosynthetic L-threonine deaminase [15].
• Restriction endonuclease analysis of the S. typhimurium ilv gene cluster provided another demonstration of the gene order as well as established the location of ilv Y between ilvA and ilvC [16].
• This putative BCAA operon is not functional as the ilvA gene is interrupted by a single mutation and the strain is auxotrophic for the three BCAAs [17].
• As based on the functional analysis of the corresponding plasmids in C. glutamicum, the DNA fragments isolated encode threonine dehydratase, acetohydroxy acid synthase, and isomeroreductase, catalyzing three subsequent reactions in Ile synthesis [1].

Anatomical context of ilvA

• The ilvA coding sequences were fused to a plastid transit peptide down stream of a modified 35S CaMV promoter [18].

Associations of ilvA with chemical compounds

• Other C. crescentus strains containing mutations at a third locus, ilvA, required either isoleucine or methionine for growth [19].
• The conclusion was reached that conditions which resulted in a temporary energy deficit brought about the major accumulation of cAMP, and this elevated level served as a signal for initiation of threonine dehydratase synthesis to supply energy by the nonoxidative degradation of threonine [10].
• Carbon balance data showed that when just one enzyme, the catabolic threonine dehydratase, was overexpressed, 70% of the carbon available for the lysine pathway was redirected into the isoleucine pathway [5].
• Pyruvate addition at the time of anaerobic shock severely affected both cAMP accumulation and threonine dehydratase synthesis; however, externally added cAMP could partially counter the pyruvate effect on enzyme synthesis [10].
• The following exchanges are noteworthy: tyr to asp in codon 26 in Y-K MUB 7; thr to ile in codon 266 in Y-K AJ 33; gly to asp in codon 262 in Y-D 3 and in Y-D 4 [20].

Other interactions of ilvA

• These experiments demonstrate that the converging transcripts from the ilvA and ilvY genes terminate in the coding region of the opposing gene [2].
• The biodegradative threonine dehydratase (tdc) operon was mapped at 68 min on the Escherichia coli K-12 chromosome [21].

References