Crystal structure of LacI member, PurR, bound to DNA: minor groove binding by alpha helices.

Published

Journal Article

The three-dimensional structure of a ternary complex of the purine repressor, PurR, bound to both its corepressor, hypoxanthine, and the 16-base pair purF operator site has been solved at 2.7 A resolution by x-ray crystallography. The bipartite structure of PurR consists of an amino-terminal DNA-binding domain and a larger carboxyl-terminal corepressor binding and dimerization domain that is similar to that of the bacterial periplasmic binding proteins. The DNA-binding domain contains a helix-turn-helix motif that makes base-specific contacts in the major groove of the DNA. Base contacts are also made by residues of symmetry-related alpha helices, the "hinge" helices, which bind deeply in the minor groove. Critical to hinge helix-minor groove binding is the intercalation of the side chains of Leu54 and its symmetry-related mate, Leu54', into the central CpG-base pair step. These residues thereby act as "leucine levers" to pry open the minor groove and kink the purF operator by 45 degrees.

Full Text

Duke Authors

Cited Authors

  • Schumacher, MA; Choi, KY; Zalkin, H; Brennan, RG

Published Date

  • November 4, 1994

Published In

Volume / Issue

  • 266 / 5186

Start / End Page

  • 763 - 770

PubMed ID

  • 7973627

Pubmed Central ID

  • 7973627

International Standard Serial Number (ISSN)

  • 0036-8075

Digital Object Identifier (DOI)

  • 10.1126/science.7973627

Language

  • eng

Conference Location

  • United States