High impact information on LEU4

• We now provide evidence showing that a large part of the 2-isopropylmalate synthase activity that is associated with the mitochondria is located in the mitochondrial matrix [1].
• The coenzyme-A-mediated inactivation of alpha-isopropylmalate synthase has been more closely investigated [2].
• The other element shows strong sequence identity with the Bas2p binding site and appears to be involved in basal and phosphate-mediated regulation of LEU4 [3].
• The metabolic importance of alpha-isopropylmalate appears to be reflected in the surprisingly multifaceted regulation of LEU4 expression [3].
• Expression of the native short form of LEU4-encoded alpha-isopropylmalate synthase behind a strong yeast promoter has enabled us to show that the short form is functional in leucine biosynthesis, is inhibited by leucine with an apparent inhibitor constant of approximately 0.4 mM, and exists as a cytoplasmic dimer [4].

Biological context of LEU4

• The new plasmid was digested to obtain a linear HIS3-carrying fragment flanked by remnants of the LEU4 region [5].
• Linkage to MET4 would place the LEU4 gene on the left arm of chromosome XIV [5].
• Integrative transformation of a LEU4fbr LEU5+ his3- strain with this fragment resulted in the deletion of the LEU4 gene from the genome of some recipients, as demonstrated by transformant phenotype, genetic analysis and the absence of RNA capable of hybridizing to a LEU4 probe [5].
• Structure of yeast LEU4. The 5' flanking region contains features that predict two modes of control and two productive translation starts [6].
• Determination of the 5' ends of the LEU4 transcript indicates the existence of four major and several minor potential transcription start sites [6].

Associations of LEU4 with chemical compounds

• Deletion of the LEU4 region by the method utilized here resulted in an amino acid auxotrophy that could be satisfied by methionine, homocysteine, or cysteine [5].
• Evidence was obtained for at least four modes of expression of LEU4: general amino acid control, leucine-specific control, basal level expression, and branched-chain amino acid-mediated repression [7].
• Determination of its nucleotide sequence showed that it was an allele of LEU4 (LEU4-1), the gene that encodes alpha-isopropyl malate synthase I (alpha-IPM synthase I), and that the mutation involved a codon deletion localised close to the 3' end of the LEU4 ORF [8].
• We characterized a trifluoroleucine-resistant mutant of Saccharomyces cerevisiae, TFL20, that has a mutation in the LEU4 gene [9].
• Furthermore, DNA sequencing of the LEU4 gene for a haploid of the mutant TFL20 revealed that aspartic acid in position 578 changes to tyrosine [10].

Other interactions of LEU4

• GCN4 binding sequences are present between the divergently transcribed MET4 and LEU4 genes [11].
• In either a leu4 or LEU4 background, each leu5 mutation causes a glycerol--phenotype [12].
• Identification by functional analysis of the gene encoding alpha-isopropylmalate synthase II (LEU9) in Saccharomyces cerevisiae [13].
• Growth in an acetate medium results in derepression of the first enzyme in the pathway, alpha-isopropylmalate synthase, and repression of the second two enzymes, alpha-isopropylmalate isomerase and beta-isopropylmalate dehydrogenase, relative to the levels found in glucose-grown cells [14].

Analytical, diagnostic and therapeutic context of LEU4

• In vitro translation of total yeast RNA followed by immunoprecipitation with anti-2-isopropylmalate synthase antibody yields two polypeptides [1].
• Restriction mapping and subcloning showed that sequences sufficient for complementation of the leu4 leu5 strain were located within a 2.2-kilobase SalI-PvuII segment [15].

References