title: The Drosophila spn-D gene encodes a RAD51C-like protein that is required exclusively during meiosis.
abstract: In Drosophila, mutations in double-strand DNA break (DSB) repair enzymes, such as spn-B, activate a meiotic checkpoint leading to dorsal-ventral patterning defects in the egg and an abnormal appearance of the oocyte nucleus. Mutations in spn-D cause an array of ovarian phenotypes similar to spn-B. We have cloned the spn-D locus and found that it encodes a protein of 271 amino acids that shows significant homology to the human RAD51C protein. In mammals the spn-B and spn-D homologs, XRCC3 and RAD51C, play a role in genomic stability in somatic cells. To test for a similar role for spn-B and spn-D in double-strand DNA repair in mitotic cells, we analyzed the sensitivity of single and double mutants to DSBs induced by exposure to X rays and MMS. We found that neither singly mutant nor doubly mutant animals were significantly sensitized to MMS or X rays. These results suggest that spn-B and spn-D act in meiotic recombination but not in repair of DSBs in somatic cells. As there is no apparent ortholog of the meiosis-specific DMC1 gene in the Drosophila genome, and given their meiosis-specific requirement, we suggest that spn-B and spn-D may have a function comparable to DMC1.
mesh_terms: D000818:Animals; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D004527:Egg Proteins / Q000502:physiology; D008540:Meiosis / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D004527:Egg Proteins; C448305:RAD51C protein, human; C114493:spn-B protein, Drosophila; C485930:spn-D protein, Drosophila