High impact information on PRI1

• The immunopurified yeast DNA polymerase--DNA primase complex is constituted by DNA polymerase I polypeptides and by three other protein species, called p74, p58 and p48, which we show to be immunologically unrelated [1].
• The gene encoding the p48 polypeptide has been identified by immunological screening of a lambda gt11 yeast genomic DNA library [1].
• Primase activity associated with free p48 was highly unstable, indicating that although p48 bears the catalytic site, its association with the other polypeptides of the polymerase-primase complex plays an important role in stabilizing enzyme activity [2].
• The nucleotide sequence of the PRI1 gene related to DNA primase in Saccharomyces cerevisiae [3].
• The primary structure and the codon usage of PRI1 suggest that this essential gene is poorly expressed in yeast cells [3].

Biological context of PRI1

• Expression of the yeast DNA primase gene, PRI1, is regulated within the mitotic cell cycle and in meiosis [4].
• We have determined the nucleotide sequence of a 1,965 bp DNA fragment containing the PRI1 locus [3].
• Furthermore, mapping of the mutations at the nucleotide level has shown that the two pri1 and two pri2 conditional alleles and one pri2 lethal allele have suffered single base-pair substitutions causing a change in amino acid residues conserved in the corresponding mouse polypeptide [5].
• Furthermore, pri1 and pri2 mutations inhibit sporulation and affect spore viability, with the unsporulated mutant cells arresting with a single nucleus, suggesting that DNA primase plays a critical role during meiosis [6].
• These three proteins, denoted p28, p36 and p48, presented, in their first 15 amino acids, homologies with glycolysis enzymes, i.e., 3-phosphoglycerate mutase, glyceraldehyde-3-phosphate dehydrogenase and enolase, respectively [7].

Associations of PRI1 with chemical compounds

• Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed the presence of five major peptides, p180, p140, p74, p58, and p48 in the immunoaffinity-purified DNA polymerase-DNA primase complex [8].
• Both the p58 and p48 subunits of yeast DNA primase appear to participate in the formation of the catalytic site of the enzyme, although UV-photocross-linking with [alpha-32P]ATP locates the ribonucleoside triphosphate binding site exclusively on the p48 polypeptide [9].

Analytical, diagnostic and therapeutic context of PRI1

• Immunopurification and immunoprecipitation studies on wild-type and mutant strains suggest that the small subunit has a major role in determining primase activity, whereas the large subunit directly interacts with DNA polymerase alpha, and either mediates or stabilizes association of the p48 polypeptide in the DNA polymerase alpha-primase complex [6].

References