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Solution structure of DinI provides insight into its mode of RecA inactivation
Author(s) -
Ramirez Benjamin E.,
Bax Ad,
Voloshin Oleg N.,
Cameriniotero R. Daniel
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.11.2161
Subject(s) - antiparallel (mathematics) , chemistry , crystallography , dna , beta sheet , biophysics , protein structure , stereochemistry , physics , biology , biochemistry , quantum mechanics , magnetic field
The Escherichia coli RecA protein triggers both DNA repair and mutagenesis in a process known as the SOS response. The 81‐residue E. coli protein DinI inhibits activity of RecA in vivo. The solution structure of DinI has been determined by multidimensional triple resonance NMR spectroscopy, using restraints derived from two sets of residual dipolar couplings, obtained in bicelle and phage media, supplemented with J couplings and a moderate number of NOE restraints. DinI has an α/β fold comprised of a three‐stranded β‐sheet and two α‐helices. The β‐sheet topology is unusual: the central strand is flanked by a parallel and an antiparallel strand and the sheet is remarkably flat. The structure of DinI shows that six negatively charged Glu and Asp residues on DinI's kinked C‐terminal α‐helix form an extended, negatively charged ridge. We propose that this ridge mimics the electrostatic character of the DNA phospodiester backbone, thereby enabling DinI to compete with single‐stranded DNA for RecA binding. Biochemical data confirm that DinI is able to displace ssDNA from RecA.