'Escherichia Coli' MutS Tetramerization Domain Structure Reveals That Stable Dimers But Not Tetramers are Essential for DNA Mismatch Repair in Vivo
The E. coli mispair binding protein MutS forms dimers and tetramers in vitro, although the functional form in vivo is under debate. Here we demonstrate that the MutS tetramer is extended in solution using small angle x-ray scattering (SAXS) and the crystal structure of the C-terminal 34 amino acids of MutS containing the tetramer-forming domain fused to maltose binding protein (MBP). Wild-type C-terminal MBP fusions formed tetramers and could bind MutS and MutS-MutL-DNA complexes. In contrast, Asp835Arg and Arg840Glu mutations predicted to disrupt tetrameric interactions only allowed dimerization of MBP. A chromosomal MutS truncation mutation eliminating the dimerization/tetramerization domain eliminated mismatch repair, whereas the tetramer-disrupting MutS Asp835Arg and Arg840Glu mutations only modestly affected MutS function. These results demonstrate that dimerization but not tetramerization of the MutS C- terminus is essential for mismatch repair.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76SF00515
- OSTI ID:
- 909793
- Report Number(s):
- SLAC-REPRINT-2007-102; JBCHA3; TRN: US200723%%189
- Journal Information:
- J.Biol.Chem.282:16354,2007, Vol. 282; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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