Lrp, a major regulatory protein in Escherichia coli, bends DNA and can organize the assembly of a higher-order nucleoprotein structure

EMBO J. 1993 Jun;12(6):2495-501.

Abstract

Lrp (Leucine-responsive regulatory protein) is a global regulatory protein that controls the expression of many operons in Escherichia coli. One of those operons, ilvIH, contains six Lrp binding sites located within a several hundred base pair region upstream of the promoter region. Analysis of the binding of Lrp to a set of circularly permuted DNA fragments from this region indicates that Lrp induces DNA bending. The results of DNase I footprinting experiments suggest that Lrp binding to this region facilitates the formation of a higher-order nucleoprotein structure. To define more precisely the degree of bending associated with Lrp binding, one or two binding sites were separately cloned into a pBend vector and analyzed. Lrp induced a bend of approximately 52 degrees upon binding to a single binding site, and the angle of bending is increased to at least 135 degrees when Lrp binds to two adjacent sites. Lrp-induced DNA bending, and a natural sequence-directed bend that exists within ilvIH DNA, may be architectural elements that facilitate the assembly of a nucleoprotein complex.

Publication types

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

MeSH terms

  • Bacterial Proteins / metabolism*
  • Base Sequence
  • Binding Sites
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / metabolism*
  • DNA, Single-Stranded / chemistry
  • DNA, Single-Stranded / metabolism
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Escherichia coli Proteins
  • Leucine-Responsive Regulatory Protein
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Nucleoproteins / chemistry
  • Nucleoproteins / metabolism*
  • Operon
  • Promoter Regions, Genetic
  • Protein Binding
  • Regulatory Sequences, Nucleic Acid
  • Transcription Factors*

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • Lrp protein, E coli
  • Nucleoproteins
  • Transcription Factors
  • Leucine-Responsive Regulatory Protein