N‐terminus of hMLH1 confers interaction of hMutLα and hMutLβ with hMutSα

  • Mismatch repair is a highly conserved system that ensures replication fidelity by repairing mispairs after DNA synthesis. In humans, the two protein heterodimers hMutSα (hMSH2‐hMSH6) and hMutLα (hMLH1‐hPMS2) constitute the centre of the repair reaction. After recognising a DNA replication error, hMutSα recruits hMutLα, which then is thought to transduce the repair signal to the excision machinery. We have expressed an ATPase mutant of hMutLα as well as its individual subunits hMLH1 and hPMS2 and fragments of hMLH1, followed by examination of their interaction properties with hMutSα using a novel interaction assay. We show that, although the interaction requires ATP, hMutLα does not need to hydrolyse this nucleotide to join hMutSα on DNA, suggesting that ATP hydrolysis by hMutLα happens downstream of complex formation. The analysis of the individual subunits of hMutLα demonstrated that the hMutSα–hMutLα interaction is predominantly conferred by hMLH1. Further experiments revealed that only the N‐terminus of hMLH1 confers this interaction. In contrast, only the C‐terminus stabilised and co‐immunoprecipitated hPMS2 when both proteins were co‐expressed in 293T cells, indicating that dimerisation and stabilisation are mediated by the C‐terminal part of hMLH1. We also examined another human homologue of bacterial MutL, hMutLβ (hMLH1–hPMS1). We show that hMutLβ interacts as efficiently with hMutSα as hMutLα, and that it predominantly binds to hMutSα via hMLH1 as well.

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Author:Guido PlotzORCiDGND, Jochen Raedle, Angela BriegerORCiDGND, Jörg TrojanORCiDGND, Stefan ZeuzemORCiDGND
Pubmed Id:https://pubmed.ncbi.nlm.nih.gov/12799449
Parent Title (English):Nucleic acids research
Publisher:Oxford Univ. Press
Place of publication:Oxford
Document Type:Article
Date of Publication (online):2006/11/07
Year of first Publication:2003
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2006/11/07
Page Number:10
First Page:3217
Last Page:3226
© Oxford University Press 2003; all rights reserved
Source:Nucleic Acids Research, 2003, Vol. 31, No. 12 3217-3226 ; DOI: 10.1093/nar/gkg420, http://nar.oxfordjournals.org/
Institutes:Medizin / Medizin
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Licence (German):License LogoDeutsches Urheberrecht