| 摘要 |
An analysis of LEU3, a leucine-specific regulatory locus encoding a factor for control of RNA levels of a group of leucine-specific genes, is provided. DNA sequence analysis of a clone of LEU3 shows that it contains an open reading frame of 886 amino acids. There are three regions of particular interest: a cluster of acidic amino acids that are located in the C-terminal half of the coding region, a region with a repeated cysteine motif, and a region of partial homology with MATalpha2. A LEU3-dependent DNA binding activity is demonstrated to interact with homologous portions of the 5'-region of LEU1 and LEU2. The sequencing of the LEU3 gene, and the identification of the key sequences within the gene, provide a means for producing the protein in deficient yeast strains and non-yeast strains, for modifying the gene in the key regions to thereby alter DNA binding with LEU1, LEU2, LEU4 and other genes for proteins and expression of LEU1, LEU2, LEU4, and LEU3 gene products, and for use within other nucleotide sequences for expression in different protein frameworks. In one application, synthesis of leucine, valine, and isoleucine, as well as the expression of the enzymes specific to leucine biosynthesis, alpha-isopropyl malate synthase, IPM isomerase, and beta-IPM dehydrogenase, may be induced or enhanced.
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