A single mutation, RecB(D1080A), eliminates RecA protein loading but not Chi recognition by RecBCD enzyme

Daniel G. Anderson, Jason J. Churchill, Stephen C. Kowalczykowski

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Homologous recombination and double-stranded DNA break repair in Escherichia coli are initiated by the multifunctional RecBCD enzyme. After binding to a double-stranded DNA end, the RecBCD enzyme unwinds and degrades the DNA processively. This processing is regulated by the recombination hot spot, Chi (χ: 5'-GCTGGTGG-3'), which induces a switch in the polarity of DNA degradation and activates RecBCD enzyme to coordinate the loading of the DNA strand exchange protein, RecA, onto the single-stranded DNA products of unwinding. Recently, a single mutation in RecB, Asp-1080 → Ala, was shown to create an enzyme (RecB(D1080A)CD) that is a processive helicase but not a nuclease. Here we show that the RecB(D1080A)CD enzyme is also unable to coordinate the loading of the RecA protein, regardless of whether χ sites are present in the DNA. However, the RecB(D1080A)CD enzyme does respond to χ sites by inactivating in a χ-dependent manner. These data define a locus of the RecBCD enzyme that is essential not only for nuclease function but also for the coordination of RecA protein loading.

Original languageEnglish (US)
Pages (from-to)27139-27144
Number of pages6
JournalJournal of Biological Chemistry
Volume274
Issue number38
DOIs
StatePublished - Sep 17 1999

ASJC Scopus subject areas

  • Biochemistry

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