title: Isolation of the gene encoding yeast single-stranded nucleic acid binding protein 1.
abstract: A yeast gene encoding SSB-1, a single-stranded nucleic acid binding protein, has been isolated by screening a lambda gt11 genomic DNA library. The gene is located on a 1.84-kilobase chromosomal Bgl II-BamHI fragment. Yeast strains carrying the high-copy-number vector YEp24 with an SSB1 gene insert overproduce SSB-1 3-fold and SSB-1 mRNA 10-fold. A typical haploid cell contains about 20,000 molecules of SSB-1; thus, the cells can tolerate up to 60,000 copies. Yeast SSB-1 was expressed in Escherichia coli cells by using a phage T7 expression system. Spores containing the gene disrupted at a point within the coding sequence germinate and grow normally; thus, the gene is not essential. Protein blots show that no SSB-1 or novel immunologically related species that might retain SSB-1 activity are present in cells containing the disrupted SSB1 genes. Southern analysis and protein blots suggest the presence in yeast of a second, related, but nonidentical gene and two immunologically related proteins of 55 kDa and 75 kDa.
mesh_terms: D004274:DNA, Recombinant / Q000032:analysis; D004277:DNA, Single-Stranded / Q000096:biosynthesis / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D004926:Escherichia coli / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D005800:Genes, Fungal; D010957:Plasmids; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000032:analysis / Q000235:genetics*
chemical_list: D004274:DNA, Recombinant; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D011994:Recombinant Proteins