Roles of Mg super(2+) in the mechanism of formation and dissociation of open complexes between Escherichia coli RNA polymerase and the lambda P sub(R) promoter: Kinetic evidence for a second open complex requiring Mg super(2+)

Comparative studies of the effects of Mg super(2+) vs Na super(+) and of acetate (OAc super(-)) vs Cl super(-) on the kinetics of formation and dissociation of E. coli) RNA polymerase (E sigma super(70))- lambda P sub(R) promoter open complexes have been used to probe the mechanism of this interacti...

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Bibliographic Details
Published in:Biochemistry (Easton) 1992-01, Vol.31 (34), p.7815-7825
Main Authors: Suh, Won Chul, Leirmo, S, Record, MT Jr
Format: Article
Language:English
Subjects:
Escherichia coli
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Summary:Comparative studies of the effects of Mg super(2+) vs Na super(+) and of acetate (OAc super(-)) vs Cl super(-) on the kinetics of formation and dissociation of E. coli) RNA polymerase (E sigma super(70))- lambda P sub(R) promoter open complexes have been used to probe the mechanism of this interaction. We propose a minimal four-step mechanism in which the specific uptake of Mg super(2+) upon conversion of RP sub(o1) to RP sub(o2) contrasts with nonspecific cation accumulation (either Na super(+) or Mg super(2+), as shown) in the dissociation of the initial closed complex (RP sub(c1)) to free promoter DNA (P) and RNA polymerase (R), and in the closing (DNA helix formation) of the initial open complex (RP sub(o1)) to form RP sub(c2), the intermediate closed complex which differs from RP sub(c1) as the result of a large conformational change in RNA polymerase.
ISSN:0006-2960