Regulation of homologous recombination: Chi inactivates RecBCD enzyme by disassembly of the three subunits
AUTOR(ES)
Taylor, Andrew F.
FONTE
Cold Spring Harbor Laboratory Press
RESUMO
We report here an unusual mechanism for enzyme regulation: the disassembly of all three subunits of RecBCD enzyme after its interaction with a Chi recombination hot spot. The enzyme, which is essential for the major pathway of recombination in Escherichia coli, acts on linear double-stranded DNA bearing a Chi site to produce single-stranded DNA substrates for strand exchange by RecA protein. We show that after reaction with DNA bearing Chi sites, RecBCD enzyme is inactivated and the three subunits migrate as separate species during glycerol gradient ultracentrifugation or native gel electrophoresis. This Chi-mediated inactivation and disassembly of purified RecBCD enzyme can account for the previously reported Chi-dependent loss of Chi activity in E. coli cells containing broken DNA. Our results support a model of recombination in which Chi regulates one RecBCD enzyme molecule to make a single recombinational exchange (‘one enzyme-one exchange’ hypothesis).
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=316601Documentos Relacionados
- RecBCD enzyme is altered upon cutting DNA at a chi recombination hotspot.
- Lambda Gam protein inhibits the helicase and chi-stimulated recombination activities of Escherichia coli RecBCD enzyme.
- The recombination hot spot chi activates RecBCD recombination by converting Escherichia coli to a recD mutant phenocopy.
- The RecD subunit of the Escherichia coli RecBCD enzyme inhibits RecA loading, homologous recombination, and DNA repair
- Interaction with the recombination hot spot chi in vivo converts the RecBCD enzyme of Escherichia coli into a chi-independent recombinase by inactivation of the RecD subunit.