Structure of the MutL C-terminal domain: a model of intact MutL and its roles in mismatch repair.
MutL assists the mismatch recognition protein MutS to initiate and coordinate mismatch repair in species ranging from bacteria to humans. The MutL N-terminal ATPase domain is highly conserved, but the C-terminal region shares little sequence similarity among MutL homologs. We report here the crystal structure of the Escherichia coli MutL C-terminal dimerization domain and the likelihood of its conservation among MutL homologs. A 100-residue proline-rich linker between the ATPase and dimerization domains, which generates a large central cavity in MutL dimers, tolerates sequence substitutions and deletions of one-third of its length with no functional consequences in vivo or in vitro. Along the surface of the central cavity, residues essential for DNA binding are located in both the N- and C-terminal domains. Each domain of MutL interacts with UvrD helicase and is required for activating the helicase activity. The DNA-binding capacity of MutL is correlated with the level of UvrD activation. A model of how MutL utilizes its ATPase and DNA-binding activities to mediate mismatch-dependent activation of MutH endonuclease and UvrD helicase is proposed.
Guarné
Alba
A
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
Ramon-Maiques
Santiago
S
Wolff
Erika M
EM
Ghirlando
Rodolfo
R
Hu
Xiaojian
X
Miller
Jeffrey H
JH
Yang
Wei
W
D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism; D004260:DNA Repair; D019281:Dimerization; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000070956:MutL Proteins; D009154:Mutation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D004247:DNA; D000251:Adenosine Triphosphatases; C506746:UvrD protein, E coli; D000070956:MutL Proteins; D004265:DNA Helicases