N-terminus of hMLH1 confers interaction of hMutL{alpha} and hMutL{beta} with hMutS{alpha}

Mismatch repair is a highly conserved system that ensures replication fidelity by repairing mispairs after DNA synthesis. In humans, the two protein heterodimers hMutS{alpha} (hMSH2-hMSH6) and hMutL{alpha} (hMLH1-hPMS2) 
Mismatch repair is a highly conserved system that ensures replication fidelity by repairing mispairs after DNA synthesis. In humans, the two protein heterodimers hMutS{alpha} (hMSH2-hMSH6) and hMutL{alpha} (hMLH1-hPMS2) constitute the centre of the repair reaction. After recognising a DNA replication error, hMutS{alpha} recruits hMutL{alpha}, which then is thought to transduce the repair signal to the excision machinery. We have expressed an ATPase mutant of hMutL{alpha} as well as its individual subunits hMLH1 and hPMS2 and fragments of hMLH1, followed by examination of their interaction properties with hMutS{alpha} using a novel interaction assay. We show that, although the interaction requires ATP, hMutL{alpha} does not need to hydrolyse this nucleotide to join hMutS{alpha} on DNA, suggesting that ATP hydrolysis by hMutL{alpha} happens downstream of complex formation. The analysis of the individual subunits of hMutL{alpha} demonstrated that the hMutS{alpha}–hMutL{alpha} 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, hMutL{beta} (hMLH1–hPMS1). We show that hMutL{beta} interacts as efficiently with hMutS{alpha} as hMutL{alpha}, and that it predominantly binds to hMutS{alpha} via hMLH1 as well.
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Metadaten
Author:Guido Plotz, Jochen Raedle, Angela Brieger, Jörg Trojan, Stefan Zeuzem
URN:urn:nbn:de:hebis:30-32700
DOI:http://dx.doi.org/10.1093/nar/gkg420
Document Type:Article
Language:English
Date of Publication (online):2006/11/07
Year of first Publication:2003
Publishing Institution:Univ.-Bibliothek Frankfurt am Main
Release Date:2006/11/07
Note:
© 2003 Oxford University Press, http://nar.oxfordjournals.org/misc/terms.dtl
Source:Nucleic Acids Research, 2003, Vol. 31, No. 12 3217-3226 ; DOI: 10.1093/nar/gkg420, http://nar.oxfordjournals.org/
HeBIS PPN:197103995
Institutes:Medizin
Dewey Decimal Classification:610 Medizin und Gesundheit
Sammlungen:Universitätspublikationen
Licence (German):License Logo Veröffentlichungsvertrag für Publikationen

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