Interactions of Exo1p with components of MutLalpha in Saccharomyces cerevisiae.
Previously, we reported evidence suggesting that Saccharomyces cerevisiae MutLalpha, composed of Mlh1p and Pms1p, was a functional member of the gyrase b/Hsp90/MutL (GHL) dimeric ATPase superfamily characterized by highly conserved ATPase domains. Similar to other GHL ATPases, these putative ATPase domains of MutLalpha may be important for the recruitment and/or activation of downstream effectors. One downstream effector candidate is Exo1p, a 5'-3' double stranded DNA exonuclease that has previously been implicated in DNA mismatch repair (MMR). Here we report yeast two-hybrid results suggesting that Exo1p can interact physically with MutLalpha through the Mlh1p subunit. We also report epistasis analysis involving MutLalpha ATPase mutations combined with exo1Delta. One interpretation of our genetic results is that MutLalpha ATPase domains function to direct Exo1p and other functionally redundant exonucleases during MMR. Finally, our results show that much of the increase in spontaneous mutation observed in an exo1Delta strain is REV3-dependent, in turn suggesting that Exo1p is also involved in one or more MMR-independent mutation avoidance pathways.
Tran
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PT
Department of Molecular and Medical Genetics, Oregon Health Sciences University, Portland 97201, USA.
Simon
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JA
Liskay
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RM
D048868:Adaptor Proteins, Signal Transducing; D026905:Amino Acid Transport Systems; D020137:Base Pair Mismatch; D002352:Carrier Proteins / Q000378:metabolism*; D004260:DNA Repair / Q000502:physiology*; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D004843:Epistasis, Genetic; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins / Q000235:genetics; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D009154:Mutation; D010446:Peptide Fragments / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D026905:Amino Acid Transport Systems; C097640:CAN1 protein, Candida albicans; D002352:Carrier Proteins; D004271:DNA, Fungal; D005656:Fungal Proteins; C088859:MLH1 protein, S cerevisiae; D046911:Macromolecular Substances; D026901:Membrane Transport Proteins; C088858:PMS1 protein, S cerevisiae; D010446:Peptide Fragments; D029701:Saccharomyces cerevisiae Proteins; D005090:Exodeoxyribonucleases; C028450:exodeoxyribonuclease I; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins