Facilitated loading of RecA protein is essential to recombination by RecBCD enzyme

Deana A. Arnold, Stephen C. Kowalczykowski

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Although the RecB2109CD enzyme retains most of the biochemical functions associated with the wild-type RecBCD enzyme, it is completely defective for genetic recombination. Here, we demonstrate that the mutant enzyme exhibits an aberrant double-stranded DNA exonuclease activity, intrinsically producing a 3'-terminal single-stranded DNA overhang that is an ideal substrate for RecA protein-promoted strand invasion. Thus, the mutant enzyme constitutively processes double-stranded DNA in the same manner as the x-modified wild-type RecBCD enzyme. However, we further show that the RecB2109CD enzyme is unable to coordinate the loading of RecA protein onto the single-stranded DNA produced, and we conclude that this inability results in the recombination-defective phenotype of the recB2109 allele. Our findings argue that the facilitated loading of RecA protein by the x- activated RecBCD enzyme is essential for RecBCD-mediated homologous recombination in vivo.

Original languageEnglish (US)
Pages (from-to)12261-12265
Number of pages5
JournalJournal of Biological Chemistry
Issue number16
StatePublished - Apr 21 2000

ASJC Scopus subject areas

  • Biochemistry


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