Functional interaction between MutL and 3'-5' exonuclease X in Escherichia coli

Archives of Biochemistry and Biophysics
Fang ChengXian-En Zhang

Abstract

Exonuclease X is a 3'-5' distributive exonuclease that functions in DNA recombination and repair. It undergoes multiple rounds of binding, hydrolysis, and release to degrade long substrate molecules and thus is very inefficient. In order to identify a cofactor that elevates the excision activity of ExoX, we screened many proteins involved in repair and recombination. We observed that MutL greatly promoted the exonuclease activity of ExoX, and then verified the interaction between MutL and ExoX using SPR and Far-Western analysis. This promotion is independent of ATP and the DNA-binding activity of MutL. We constructed two deletion mutants to analyze this interaction and its regulation of ExoX activity, and found that this functional interaction with ExoX is mainly due to ionic interactions with the N-terminus of MutL. This adds a new role to MutL and gives a clue to MutL's possible regulation on other DnaQ family exonuclease members.

References

Mar 21, 1998·Nucleic Acids Research·K DrotschmannM G Marinus
Mar 29, 2000·The Journal of Biological Chemistry·C Spampinato, P Modrich
Jun 13, 2006·Cancer Cell·Jean Y J Wang, Winfried Edelmann
Dec 3, 2009·BioEssays : News and Reviews in Molecular, Cellular and Developmental Biology·Yaroslava Y Polosina, Claire G Cupples

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