A core activity associated with the N terminus of the yeast RAD52 protein is revealed by RAD51 overexpression suppression of C-terminal rad52 truncation alleles.
C-terminal rad52 truncation and internal deletion mutants were characterized for their ability to repair MMS-induced double-strand breaks and to produce viable spores during meiosis. The rad52-Delta251 allele, encoding the N-terminal 251 amino acids of the predicted 504-amino-acid polypeptide, supports partial activity for both functions. Furthermore, RAD51 overexpression completely suppresses the MMS sensitivity of a rad52-Delta251 mutant. The absence of the C terminus in the truncated protein makes it likely that suppression occurs by bypassing the C-terminal functions of Rad52p. RAD51 overexpression does not suppress the low level of spore viability that the rad52-Delta251 allele causes and only partially suppresses the defect in rad52 alleles encoding the N-terminal 292 or 327 amino acids. The results of this study also show that intragenic complementation between rad52 alleles is governed by a complex relationship that depends heavily on the two alleles involved and their relative dosage. In heteroallelic rad52 diploids, the rad52-Delta251 allele does not complement rad52 missense mutations altering residues 61 or 64 in the N terminus. However, complementation is achieved with each of these missense alleles when the rad52-Delta251 allele is overexpressed. Complementation also occurs between rad52-Delta327 and an internal deletion allele missing residues 210 through 327. We suggest that the first 251 amino acids of Rad52p constitute a core domain that provides critical RAD52 activities.
Asleson
E N
EN
Department of Biochemistry, University of Minnesota, Minneapolis, Minnesota 55455-0347, USA.
Okagaki
R J
RJ
Livingston
D M
DM
D000483:Alleles; D003433:Crosses, Genetic; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005838:Genotype; D006238:Haploidy; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D016296:Mutagenesis; D051135:Rad51 Recombinase; D051721:Rad52 DNA Repair and Recombination Protein; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D013172:Spores, Fungal; D013489:Suppression, Genetic
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D008741:Methyl Methanesulfonate; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase