Disease relevance of ILV1

• Complementation of a threonine dehydratase-deficient Nicotiana plumbaginifolia mutant after Agrobacterium tumefaciens-mediated transfer of the Saccharomyces cerevisiae ILV1 gene [1].
• The sites of amino acid changes of two E. coli K-12 ilvA alleles with altered response to isoleucine are consistent with the conclusion that the C-terminal portion of biosynthetic Tda is involved in allosteric regulation [2].
• The nucleotide sequence of the gene, ilvA, for biosynthetic threonine deaminase (Tda) from Salmonella typhimurium was determined [2].

High impact information on ILV1

• Interestingly, an ABF1-binding site can also functionally replace the ILV1 REB1-binding site [3].
• The ILV1 gene of Saccharomyces cerevisiae encodes the first committed step in isoleucine biosynthesis and is regulated by general control of amino acid biosynthesis [3].
• The Saccharomyces cerevisiae ILV1 gene, encoding threonine dehydratase (EC 4.2.1.16) was fused to the transferred DNA nopaline synthase promoter and the 3' noncoding region of the octopine synthase gene [1].
• Similarly, deletion of the Reb1p-binding site, albeit affecting ILV1 expression, had no detectable effect on chromatin at the ILV1 promoter [4].
• Analysis of the chromatin structure at the yeast ILV1 locus revealed highly positioned nucleosomes covering the entire locus except for a hypersensitive site in the promoter region [4].

Biological context of ILV1

• Further deletion analysis of the ILV1 promoter region identified a second element also required for GCN4-independent basal-level ILV1 expression [5].
• Phenotypic suppression of ilv1 can occur by inducer-mediated transcriptional activation of the CHA1 gene [6].
• The absence of a good correlation between effects of these elements on gene activity and on chromatin structure at the ILV1 promoter indicates that the chromatin organization present at the ILV1 promoter is independent of the known regulatory elements and most likely dictated directly by the DNA sequence [4].
• The existence of a second A*T-rich element (25 As out of 33 nucleotides) present six base pairs upstream of the Reb1p-binding site, suggested that nucleosome exclusion from the hypersensitive site in the ILV1 promoter region might be dictated by synergistic action of the two poly(dA*dT) elements [4].
• The ILV1 gene of the yeast Arxula adeninivorans LS3 (AILV1) has been cloned from a genomic library, characterized and used as an auxotrophic selection marker for transformation of plasmids into this yeast [7].

Associations of ILV1 with chemical compounds

• The ILV1 gene of Saccharomyces cerevisiae encodes the anabolic threonine deaminase, which catalyzes the first committed step in isoleucine biosynthesis [6].
• It increases the size of the threonine pool, by 15- to 20-fold, which is sufficient to induce CHA1 transcription, thereby creating a metabolic bypass of ilv1 [6].
• Threonine can also be deaminated by a second serine/threonine deaminase encoded by the CHA1 gene [6].
• Both threonine deaminase activity and ILV1 mRNA levels increase in mutants (gcd2 and gcd3) having constitutively depressed levels of enzymes under the general control of amino acid biosynthesis, as well as in response to starvation for tryptophan and branched-chain amino acid imbalance [8].
• Starting from a strain carrying a ilv1- mutation, a new mutation affecting the ability to utilize L-threonine as nitrogen source was selected [9].

Physical interactions of ILV1

• Datin, a yeast poly(dA:dT)-binding protein, behaves as an activator of the wild-type ILV1 promoter and interacts synergistically with Reb1p [5].

Other interactions of ILV1

• A mutated ABF1 site that displays a very low affinity for ABF1 does not functionally replace the ILV1 REB1 site [3].
• The strains, which originally lacked alpha-galactosidase activity (Mel-), had been transformed with a DNA fragment which possessed an ILV1-SMR1 allele of the ILV2 gene and a MEL1 gene [10].
• Thus, the ILV1 gene is under general amino acid control, as is the case for both the ILV5 and the transaminase gene [8].
• The results are consistent with the absence of heme in the closely related enzymes O-acetylserine sulfhydrylase, threonine deaminase, and tryptophan synthase [11].
• A sequence comparison among all the reported mutant aspartate kinases suggests that not all residues involved in regulation of the activity are clustered in the so-called regulatory domain, as is the case of that mutated in AK-R7, another deregulated aspartate kinase obtained with the same strategy of ilv1 suppression [12].

References