The isolation and characterization of mutants of the integration host factor (IHF) of Escherichia coli with altered, expanded DNA-binding specificities

E. C. Lee, L. M. Hales, R. I. Gumport, J. F. Gardner

Research output: Contribution to journalArticlepeer-review

Abstract

The integration host factor (IHF) of Escherichia coli is a small, basic protein that is required for λ site-specific recombination and a variety of cellular processes. It is composed of two subunits, α and β, that are encoded by the himA and hip (himD) genes, respectively. IHF is a sequence-specific DNA-binding protein and bends the DNA when it binds. We have used the bacteriophage P22-based challenge phage selection to isolate suppressor mutants with altered, expanded DNA binding specificities. The suppressors were isolated by selecting mutants that recognize variants of the phage λ H'IHF recognition site. Two of the mutants recognize both the wild-type and a single variant site and contain amino acid substitutions at positions 64 (Pro to Leu) or 65 (Lys to Ser) of the α subunit. These substitutions are in a region of the protein that is predicted to contain a flexible arm that interacts with DNA. Three other mutants, which recognize the wild-type and a different variant site, contain amino acid substitutions at position 44 (Glu to Lys, Val or Gly) of the β subunit. These substitutions are in the middle of a predicted β-strand of the subunit. We discuss the possible mechanisms of suppression by the mutants in terms of a model of the IHF-DNA complex proposed by Yang and Nash [Cell, 57, 869-880 (1989)].

Original languageEnglish (US)
Pages (from-to)305-313
Number of pages9
JournalEMBO Journal
Volume11
Issue number1
DOIs
StatePublished - 1992

Keywords

  • Altered DNA binding specificity
  • IHF
  • P22 challenge phage
  • Recognition site mutants
  • Suppressor mutants

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

Fingerprint

Dive into the research topics of 'The isolation and characterization of mutants of the integration host factor (IHF) of Escherichia coli with altered, expanded DNA-binding specificities'. Together they form a unique fingerprint.

Cite this