Disease relevance of ILV2

• Comparison of deduced amino acid sequences indicates considerable conservation between the yeast protein and the large subunits of the E. coli ALS II and ALS III isozymes [1].
• Some ALS/AHASs also catalyze the (non-physiological) oxidative decarboxylation of pyruvate, leading to peracetic acid; the possible relationship of this process to oxygen toxicity is considered [2].
• We previously reported the cloning and sequencing of the acetohydroxy acid synthase (AHAS) genes from Brevibacterium flavum MJ233 [3].
• A series of mutant human and yeast copper-zinc superoxide dismutases has been prepared, with mutations corresponding to those found in familial amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease) [4].
• MALDI-TOF analysis of the 65 kDa protein led to its identification as acetolactate synthase large subunit (EC 2.2.1.6; ALS), the putatively assigned ORF sll1981 of Synechocystis sp. PCC6803 [5].

High impact information on ILV2

• The yeast interaction trap system allowed us to determine whether these mutations in SOD1 caused novel protein interactions not observed with wild-type SOD1 and which might participate in the generation of the ALS phenotype [6].
• The instability of rho+ mtDNA in delta ilv5 cells is not simply a consequence of a block in branched-chain amino acid biosynthesis, since mtDNA is stable in cells with a null allele of the ILV2 gene, which encodes another enzyme of that pathway [7].
• Several of the ALS-associated mutant copper-zinc superoxide dismutases were also found to be reduced by ascorbate at significantly greater rate than the wild-type proteins [4].
• The ALS (agglutinin-like sequence) gene family encodes proteins that play a role in adherence of the yeast Candida albicans to endothelial and epithelial cells [8].
• Mutagenesis of this completely conserved residue in Escherichia coli AHAS isozyme II (Arg(276)) confirms that it is required for rapid and specific reaction of the second ketoacid [9].

Chemical compound and disease context of ILV2

• The yeast ilv2 gene, encoding acetolactate synthase, was subcloned in an Escherichia coli expression vector [10].

Biological context of ILV2

• FLP-FRT mediated intrachromosomal recombination on a tandemly duplicated YEp integrant at the ILV2 locus of chromosome XIII in Saccharomyces cerevisiae [11].
• ILV2 upstream deletion analyses and high-copy transformation of the positive regulatory locus LEU3 ruled out the possibility of LEU3 protein binding palindromes mediating the branched chain amino acid dependent auxotrophy [12].
• Nucleotide sequence of the yeast ILV2 gene which encodes acetolactate synthase [1].
• Consensus sequences for initiation and termination of transcription that are consistent with the ends of the ILV2 mRNA, as well as general amino acid control regulatory sequences have been identified [1].
• The coding sequence for the ILV2 polypeptide contains 2061 base pairs [1].

Anatomical context of ILV2

• The amino acid sequence in this region shows similarities to yeast mitochondrial transit sequences and may function as such, since yeast ALS is localized in the mitochondria [1].

Associations of ILV2 with chemical compounds

• Chimaeric genes were constructed containing the 5' upstream and partial coding sequence of SMR1--a sulfometuron methyl resistant allele of the ILV2 locus [13].
• The yeast ILV2 gene encodes acetolactate synthase, the first enzyme in the biosynthesis of isoleucine and valine [14].
• Antisense RNA inhibition was enhanced in galactose medium containing sulfometuron methyl and in gcn4 cells deficient for positive regulation of the ILV2 locus [13].
• Genetic modification of brewers' yeast to reduce diacetyl formation is being carried out by mutation of ILV2 [15].
• ALS-specific activity in strains carrying the wild-type ILV2 allele exhibited strong feedback inhibition by valine and was sensitive to SM [16].

Regulatory relationships of ILV2

• Reconstitution studies showed that the ilv6 protein stimulates the catalytic activity of the ilv2 protein by up to 7-fold (from 6.8 +/- 0.7 to 49.0 +/- 1.8 U/mg) and confers upon it sensitivity to inhibition by valine (Ki = 0.16 +/- 0.02 mM) [17].

Other interactions of ILV2

• Thus in addition to general regulation of ILV2, GCN4 functions in basal level expression when the locus is subject to specific repression by pathway end product [12].
• The mutations occur in three linkage groups, designated SMR1, smr2 and smr3 [18].
• 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 [19].
• Isogenic [cir (o)] and [cir+] diploids formed by crossing the [cir (o)] TD strain to complementary haploids were analyzed for plasmid marker loss and chromosomal DNA alterations in the presence and absence of selection pressure for the URA3 and SMR1 plasmid borne markers [11].

Analytical, diagnostic and therapeutic context of ILV2

• Second, molecular cloning of the ILV2 gene permitted the isolation of mutations in the cloned gene which result in the production of SM-resistant ALS [18].
• Sequence analysis indicated a C to T change at position 575 of the ILV2 coding sequence, which results in a proline transition to leucine at position 192 [20].
• Nucleotide sequence analysis and site-directed mutagenesis revealed that the thi1 mutation is a single base substitution which causes the conserved amino acid substitution D176E in the AHAS protein [21].
• A different mutation (SMR1B) to SMR1-410 (ilv2), which determines resistance to sulfometuron methyl in Saccharomyces cerevisiae, was cloned by PCR [20].
• Immunofluorescence microscopy of rust-infected leaves detected high concentrations of THI1p in haustoria, and only low amounts in intercellular hyphae [22].

References