Specificity of DNA binding and dimerization by CspE from Escherichia coli

DOI

10.1074/jbc.M606414200

Document Type

Journal Article

Publication Date

12-29-2006

Publication Title

Journal of Biological Chemistry

Volume

281

Issue

52

First Page

40208

Last Page

40215

ISSN

219258

Abstract

The CspE protein from Escherichia coli K12 is a single-stranded nucleic acid-binding protein that plays a role in chromosome condensation in vivo. We report here that CspE binds to single-stranded DNA containing 6 or more contiguous dT residues with high affinity (KD < 30 nM). The interactions are predominantly through base-specific contacts. When an oligonucleotide contains fewer than 6 contiguous dT residues, the CspE interactions with single-stranded DNA are primarily electrostatic. The minimal length of single-stranded DNA to which CspE binds in a salt-resistant manner is eight nucleotides. We also show that CspE exists as a dimer in solution. We present a possible mechanism to explain the role of CspE in chromosome condensation in vivo by CspE binding to distant DNA regions in the chromosome and dimerizing, thereby condensing the intervening DNA.

Open Access

Green Accepted

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