Disruptions of the Ustilago maydis REC2 gene identify a protein domain important in directing recombinational repair of DNA.
The REC2 gene of Ustilago maydis encodes a homologue of the Escherichia coli RecA protein and was first identified in a screen for UV-sensitive mutants. The original isolate, rec2-1, was found to be deficient in repair of DNA damage, genetic recombination and meiosis. We report here that the rec2-197 allele, which was constructed by gene disruption, retains some biological activity and is partially dominant with respect to REC2. The basis for the residual activity is probably as a result of expression of a diffusible product from the rec2-197 allele that augments or interferes with REC2 functions. This product appears to be a polypeptide expressed from a remnant of the 5' end of the open reading frame that was not removed in creating the gene disruption. The mutator activity and disturbed meiosis of rec2-197 suggest that the Rec2 protein functions in a process that avoids spontaneous mutation and insures faithful meiotic chromosome segregation. A prediction based on the phenotype of rec2-197 is that Rec2 protein interacts with one or more other proteins in directing these functions. To identify interacting proteins we performed a yeast two-hybrid screen and found Rad51 as a candidate. Rec2-197 and Rad51 appear to interact to a similar degree.
Kojic
M
M
Hearst Microbiology Research Center, Department of Microbiology and Immunology, Cornell University Weill Medical College, New York, NY 10021, USA.
Thompson
C W
CW
Holloman
W K
WK
D000595:Amino Acid Sequence; D001665:Binding Sites; D020090:Chromosome Segregation; D004260:DNA Repair / Q000187:drug effects / Q000235:genetics* / Q000528:radiation effects; D004171:Diploidy; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D006720:Homozygote; D008540:Meiosis; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D008969:Molecular Sequence Data; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D013172:Spores, Fungal / Q000502:physiology; D020798:Two-Hybrid System Techniques; D014466:Ultraviolet Rays; D014588:Ustilago / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D015003:Yeasts / Q000235:genetics
D005656:Fungal Proteins; D009153:Mutagens; C088888:REC2 protein, Ustilago maydis; D011993:Recombinant Fusion Proteins; D008741:Methyl Methanesulfonate