The PMS2 subunit of human MutLalpha contains a metal ion binding domain of the iron-dependent repressor protein family.
DNA mismatch repair (MMR) is responsible for correcting replication errors. MutLalpha, one of the main players in MMR, has been recently shown to harbor an endonuclease/metal-binding activity, which is important for its function in vivo. This endonuclease activity has been confined to the C-terminal domain of the hPMS2 subunit of the MutLalpha heterodimer. In this work, we identify a striking sequence-structure similarity of hPMS2 to the metal-binding/dimerization domain of the iron-dependent repressor protein family and present a structural model of the metal-binding domain of MutLalpha. According to our model, this domain of MutLalpha comprises at least three highly conserved sequence motifs, which are also present in most MutL homologs from bacteria that do not rely on the endonuclease activity of MutH for strand discrimination. Furthermore, based on our structural model, we predict that MutLalpha is a zinc ion binding protein and confirm this prediction by way of biochemical analysis of zinc ion binding using the full-length and C-terminal domain of MutLalpha. Finally, we demonstrate that the conserved residues of the metal ion binding domain are crucial for MMR activity of MutLalpha in vitro.
Kosinski
Jan
J
Laboratory of Bioinformatics and Protein Engineering, International Institute of Molecular and Cell Biology, Trojdena 4, 02-109 Warsaw, Poland.
Plotz
Guido
G
Guarné
Alba
A
Bujnicki
Janusz M
JM
Friedhoff
Peter
P
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D053843:DNA Mismatch Repair; D045643:DNA Repair Enzymes / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007501:Iron / Q000378:metabolism*; D000070976:Mismatch Repair Endonuclease PMS2; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000070956:MutL Proteins; D010802:Phylogeny; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015032:Zinc / Q000378:metabolism
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C500929:MutLalpha protein, human; D021122:Protein Subunits; D012097:Repressor Proteins; D007501:Iron; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; D000070956:MutL Proteins; D045643:DNA Repair Enzymes; D015032:Zinc