Cloning, sequencing, disruption and phenotypic analysis of uvsC, an Aspergillus nidulans homologue of yeast RAD51

Abstract

We have cloned the uvsC gene of Aspergillus nidulans by complementation of the A. nidulans uvsC114 mutant. The predicted protein UVSC shows 67.4% sequence identity to the Saccharomyces cerevisiae Rad51 protein and 27.4% sequence identity to the Escherichia coli RecA protein. Transcription of uvsC is induced by methyl-methane sulphonate (MMS), as is transcription of RAD51 of yeast. Similar levels of uvsC transcription were observed after MMS induction in a uvsC+ strain and the uvsC114 mutant. The coding sequence of the uvsC114 allele has a deletion of 6 bp, which results in deletion of two amino acids and replacement of one amino acid in the translation product. In order to gain more insight into the biological function of the uvsC gene, a uvsC null mutant was constructed, in which the entire uvsC coding sequence was replaced by a selectable marker gene. Meiotic and mitotic phenotypes of a uvsC+ strain, the uvsC114 mutant and the uvsC null mutant were compared. The uvsC null mutant was more sensitive to both UV and MMS than the uvsC114 mutant. The uvsC114 mutant arrested in meiotic prophase-I. The uvsC null mutant arrested at an earlier stage, before the onset of meiosis. One possible interpretation of these meiotic phenotypes is that the A. nidulans homologue of Rad51 of yeast has a role both in the specialized processes preceding meiosis and in meiotic prophase I.

A Point Mutation in theAspergillus nidulans sonBNup98 Nuclear Pore Complex Gene Causes Conditional DNA Damage Sensitivity

“…To further investigate this, we determined if sonB1 mutants genetically interacted with mutants defective in different aspects of the DNA damage response in A. nidulans (Kafer and Mayor 1986;Yoon et al 1995;Kafer and May 1997;van Heemst et al 1997;Ye et al 1997;De Souza et al 1999;Hofmann and Harris 2000;Bruschi et al 2001;Semighini et al 2003;Malavazi et al 2006;Nayak et al 2006). Most striking were the genetic interactions between sonB1 and mutants of the A. nidulans NBS1 ortholog scaA NBS1 (Bruschi et al 2001).…”

“…DNA double-strand breaks are repaired by either homologous recombination or nonhomologous end joining (NHEJ). In A. nidulans, the uvsC Rad51 gene encodes a Rad51 ortholog and uvsC Rad51 mutants are sensitive to DNA double-strand breaks and display defects in homologous recombination (Chae and Kafer 1997;Seong et al 1997;van Heemst et al 1997;Ichioka et al 2001). We generated the sonB1 uvsC114…”

Double-stranded DNA breaks and gene functions in recombination and meiosis

“…RAD51 homologs have been isolated and characterized in a wide range of organisms [61,70,[80][81][82][83][84]. The fission yeast RAD51 homolog RHP51 plays roles similar to those of the budding yeast RAD51, with roles that are overlapping with and distinct from those of the fission yeast DMC1 gene in DSBs repair and meiotic recombination [72,81].…”

“…The fission yeast RAD51 homolog RHP51 plays roles similar to those of the budding yeast RAD51, with roles that are overlapping with and distinct from those of the fission yeast DMC1 gene in DSBs repair and meiotic recombination [72,81]. The RAD51 homolog in Aspergillus nidulans shows a 67.4% sequence identity to budding yeast RAD51 [80]. While a deletion of two amino acid residues in the A. nidulans RAD51 homolog (uvsC) causes arrest at meiotic prophase I, a null mutation causes the failure of meiotic cells to enter meiosis, indicating that this gene has a function prior to entering meiosis [80].…”

“…The RAD51 homolog in Aspergillus nidulans shows a 67.4% sequence identity to budding yeast RAD51 [80]. While a deletion of two amino acid residues in the A. nidulans RAD51 homolog (uvsC) causes arrest at meiotic prophase I, a null mutation causes the failure of meiotic cells to enter meiosis, indicating that this gene has a function prior to entering meiosis [80]. In Drosophila females, RAD51 plays essential roles in repairing meiotic DSBs and also in meiotic chromosome pairing [85,86].…”