title: Sequential folding of UmuC by the Hsp70 and Hsp60 chaperone complexes of Escherichia coli.
abstract: Replication-blocking lesions generate a signal in Escherichia coli that leads to the induction of the multigene SOS response. Among the SOS-induced genes are umuD and umuC, whose products are necessary for the increased mutation rate in induced bacteria. The mutations are likely to result from replication across the DNA lesion, and such a bypass event has been reconstituted in vitro (Rajagopalan, M., L, C., Woodgate, R., O'Donnel, M., Goodman, M. F., Echols, H. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 10777-10781). In this work, we show that the chaperone proteins promote the proper folding of UmuC protein in vitro. We treated purified and inactive UmuC with Hsp70 and Hsp60. After Hsp70 treatment, the DNA binding activity of UmuC was recovered, but the ability to promote replication across DNA lesions was not. However, lesion bypass activity was recovered upon further treatment with Hsp60. The biological significance of such a folding pathway for UmuC protein is strengthened by in vivo evidence for a role of DnaK in UV-induced mutagenesis.
authors.affiliation: Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
authors.forename: M A
authors.initials: MA
authors.lastname: Petit
authors.forename: W
authors.initials: W
authors.lastname: Bedale
authors.forename: J
authors.initials: J
authors.lastname: Osipiuk
authors.forename: C
authors.initials: C
authors.lastname: Lu
authors.forename: M
authors.initials: M
authors.lastname: Rajagopalan
authors.forename: P
authors.initials: P
authors.lastname: McInerney
authors.forename: M F
authors.initials: MF
authors.lastname: Goodman
authors.forename: H
authors.initials: H
authors.lastname: Echols
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000502:physiology*; D018835:Chaperonin 10; D018834:Chaperonin 60; D018833:Chaperonins; D004260:DNA Repair; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry; D004259:DNA-Directed DNA Polymerase; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000502:physiology*; D016296:Mutagenesis; D017510:Protein Folding; D011506:Proteins / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011506:Proteins; C078202:UmuC protein, E coli; D004259:DNA-Directed DNA Polymerase; D018833:Chaperonins; C063842:dnaK protein, E coli