Документ взят из кэша поисковой машины. Адрес оригинального документа : http://kodomo.cmm.msu.ru/~kleva/term2/abstract.txt Дата изменения: Thu Mar 1 20:10:25 2007 Дата индексирования: Tue Oct 2 08:03:04 2012 Кодировка:

Transformation of MutL by ATP binding and hydrolysis: a switch in DNA mismatch
repair.

Ban C, Junop M, Yang W.

Laboratory of Molecular Biology, National Institute of Diabetes and Digestive
and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892,
USA.

The MutL DNA mismatch repair protein has recently been shown to be an ATPase and
to belong to an emerging ATPase superfamily that includes DNA topoisomerase II
and Hsp90. We report here the crystal structures of a 40 kDa ATPase fragment of
E. coli MutL (LN40) complexed with a substrate analog, ADPnP, and with product
ADP. More than 60 residues that are disordered in the apoprotein structure
become ordered and contribute to both ADPnP binding and dimerization of LN40.
Hydrolysis of ATP, signified by subsequent release of the gamma-phosphate,
releases two key loops and leads to dissociation of the LN40 dimer. Dimerization
of the LN40 region is required for and is the rate-limiting step in ATP
hydrolysis by MutL. The ATPase activity of MutL is stimulated by DNA and likely
acts as a switch to coordinate DNA mismatch repair.