Protein-DNA conformational changes in the crystal structure of a lambda Cro-operator complex

Proc Natl Acad Sci U S A. 1990 Oct;87(20):8165-9. doi: 10.1073/pnas.87.20.8165.

Abstract

The structure of a complex of bacteriophage lambda Cro protein with a 17-base-pair operator has been determined at 3.9-A resolution. Isomorphous derivatives obtained by the synthesis of site-specific iodinated DNA oligomers were of critical importance in solving the structure. The crystal structure contains three independent Cro-operator complexes that have very similar, although not necessarily identical, conformations. In the complex, the protein dimer undergoes a large conformational change relative to the crystal structure of the free protein. One monomer rotates by about 40 degrees relative to the other, this being accomplished primarily by a twisting of the two beta-sheet strands that connect one monomer with the other. In the complex, the DNA is bent by about 40 degrees into the shape of a boomerang but maintains essentially Watson-Crick B-form. In contrast to other known protein-DNA complexes, the DNA is not stacked end-to-end. The structure confirms the general features of the model previously proposed for the interaction of Cro with DNA.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Bacteriophage lambda / genetics
  • Bacteriophage lambda / metabolism*
  • DNA-Binding Proteins*
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Operon*
  • Protein Binding
  • Protein Conformation
  • Repressor Proteins / metabolism*
  • Transcription Factors / metabolism
  • Viral Proteins
  • Viral Regulatory and Accessory Proteins
  • X-Ray Diffraction

Substances

  • DNA-Binding Proteins
  • Repressor Proteins
  • Transcription Factors
  • Viral Proteins
  • Viral Regulatory and Accessory Proteins
  • phage repressor proteins