Differential inhibition of the DNA translocation and DNA unwinding activities of DNA helicases by the Escherichia coli tus protein Journal Article


Authors: Hiasa, H.; Marians, K. J.
Article Title: Differential inhibition of the DNA translocation and DNA unwinding activities of DNA helicases by the Escherichia coli tus protein
Abstract: Binding of the Escherichia coli Tus protein to its cognate nonpalindromic binding site on duplex DNA (a Ter sequence) is sufficient to arrest the progression of replication forks in a Ter orientation-dependent manner in vivo and in vitro. In order to probe the molecular mechanism of this inhibition, we have used a strand displacement assay to investigate the effect of Tus on the DNA helicase activities of DnaB, PriA, UvrD (helicase II), and the φX-type primosome. When the substrate was a short oligomer hybridized to a circular single-stranded DNA, strand displacement by DnaB, PriA, and the primosome (in both directions), but not UvrD, was blocked by Tus in a polar fashion. However, no inhibition of either DnaB or UvrD was observed when the substrate carried an elongated duplex region. With this elongated substrate, PriA helicase activity was only inhibited partially (by 50%). On the other hand, both the 5′ → 3′ and 3′ → 5′ helicase activities of the primosome were inhibited almost completely by Tus with the elongated substrate. These results suggest that while Tus can inhibit the translocation of some proteins along single-stranded DNA in a polar fashion, this generalized effect is insufficient for the inhibition of bona fide DNA helicase activity.
Keywords: controlled study; dna binding protein; dna-binding proteins; nonhuman; dna replication; enzyme inhibition; enzyme activity; enzyme substrate; structure activity relation; bacterial protein; bacterial proteins; double stranded dna; molecular sequence data; escherichia coli; substrate specificity; base sequence; binding site; dna sequence; helicase; single stranded dna; dna, bacterial; dna helicases; protein dna interaction; dna fragment; dna strand; dna hybridization; circular dna; priority journal; article; support, u.s. gov't, p.h.s.; terminator regions (genetics)
Journal Title: Journal of Biological Chemistry
Volume: 267
Issue: 16
ISSN: 0021-9258
Publisher: American Society for Biochemistry and Molecular Biology  
Date Published: 1992-06-05
Start Page: 11379
End Page: 11385
Language: English
PUBMED: 1317865
PROVIDER: scopus
DOI/URL:
Notes: Article -- Source: Scopus
Citation Impact
MSK Authors
  1. Kenneth Marians
    129 Marians
  2. Hiroshi   Hiasa
    21 Hiasa