PDBsum entry 2a7z

Recombination regulator

PDB id: 2a7z

Contents

Protein chain

167 a.a.

Theoretical model

PDB id:

2a7z

Name:

Recombination regulator

Title:

Molecular model of recx

Structure:

Regulatory protein recx. Chain: a. Synonym: oraa protein

Source:

Escherichia coli. Bacteria

Authors:

S.Mishra,P.A.Mazumdar,J.Dey,A.K.Das

Key ref:

S.Mishra et al. (2003). Molecular modeling of RecX reveals its mode of interaction with RecA. Biochem Biophys Res Commun, 312, 615-622. PubMed id: 14680809 DOI: 10.1016/j.bbrc.2003.10.164

Date:

07-Jul-05 Release date: 25-Oct-05

Protein chain

P33596  (RECX_ECOLI) -  Regulatory protein RecX

Seq: 166 a.a.

Struc: 167 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

DOI no: 10.1016/j.bbrc.2003.10.164

Biochem Biophys Res Commun 312:615-622 (2003)

PubMed id: 14680809

Molecular modeling of RecX reveals its mode of interaction with RecA.

S.Mishra, P.A.Mazumdar, J.Dey, A.K.Das.

ABSTRACT

The protein RecA is involved in homologous recombination, DNA repair and also catalyzes DNA strand exchange. RecX gene is downstream of recA and the gene product RecX is supposed to be important for RecA regulation. Recombinant RecX is purified to homogeneity, and circular dichroism (CD) and FTIR spectroscopy show the protein to exist mostly in helical conformation. The fluorescence emission maxima of the native and the denatured protein and the steady-state fluorescence quenching studies with acrylamide indicate the presence of tryptophan residues partially exposed to the bulk solvent. Denaturation studies with urea and guanidine hydrochloride by use of spectroscopic methods, fluorescence, and CD also confirm the instability of the protein and unfolding occurs following a two-state model. Mass spectrometry and gel permeation chromatography suggest the monomeric form of the protein. Molecular modeling of RecX represents the molecule as extended and helical bundle in conformity with the spectroscopic results. To understand the mechanism of RecX in the regulation of RecA the structural model of RecA-RecX has been discussed. In this proposed model, entry of RecX into hexameric RecA filament prevents binding of ssDNA and also inhibits ATPase activity.