Mapping the dimer interface in the C-terminal domains of the yeast MLH1-PMS1 heterodimer.
Yeast MutLalpha is a heterodimer of MLH1 and PMS1 that participates in a variety of DNA transactions, including DNA mismatch repair. Formation of the MutLalpha heterodimer requires that the C-terminal domains of MLH1 and PMS1 interact in a manner that is not yet fully understood. Here we investigate the interactions involved in heterodimerization. Using protein surface modification and mass spectrometry, we identify numerous lysine residues that are exposed to solvent in monomeric MLH1. A corresponding analysis of the MLH1-PMS1 heterodimer reveals that three of these exposed residues, K665, K675, and K704, are no longer solvent accessible in the heterodimer, suggesting that they are within the dimer interface. We refine secondary structure predictions and sequence alignments of C-terminal residues of seven eukaryotic MutL homologues and then develop homology models for the N- and C-terminal domains of MLH1. On the basis of this information, we present a model for interaction of the C-terminal domains of MLH1 and PMS1.
Cutalo
Jenny M
JM
Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, P.O. Box 12233, Research Triangle Park, North Carolina 27709, USA.
Darden
Thomas A
TA
Kunkel
Thomas A
TA
Tomer
Kenneth B
KB
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D019281:Dimerization; D004578:Electron Spin Resonance Spectroscopy; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010449:Peptide Mapping; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D053719:Tandem Mass Spectrometry
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C088859:MLH1 protein, S cerevisiae; C074770:MutL protein, E coli; C088858:PMS1 protein, S cerevisiae; D010446:Peptide Fragments; D029701:Saccharomyces cerevisiae Proteins; D000251:Adenosine Triphosphatases; D000070957:MutL Protein Homolog 1; D000070956:MutL Proteins