PDBsum entry 2m1b

Transcription regulator

PDB id: 2m1b

Contents

Protein chain

116 a.a.

PDB id:

2m1b

Name:

Transcription regulator

Title:

Solution structure of the chxr DNA-binding domain

Structure:

Transcriptional regulatory protein, c terminal family protein. Chain: a. Engineered: yes

Source:

Chlamydia trachomatis. Organism_taxid: 887712. Strain: l2/434/bu. Gene: ctl0894, ctl2c_660. Expressed in: escherichia coli. Expression_system_taxid: 469008.

NMR struc:

25 models

Authors:

J.M.Hickey,A.M.Anbanandam,S.P.Hefty

Key ref:

M.L.Barta et al. (2014). Atypical response regulator ChxR from Chlamydia trachomatis is structurally poised for DNA binding. Plos One, 9, e91760. PubMed id: 24646934 DOI: 10.1371/journal.pone.0091760

Date:

21-Nov-12 Release date: 26-Mar-14

Protein chain

F9YCU1  (F9YCU1_CHLTC) -

DOI no: 10.1371/journal.pone.0091760

Plos One 9:e91760 (2014)

PubMed id: 24646934

Atypical response regulator ChxR from Chlamydia trachomatis is structurally poised for DNA binding.

M.L.Barta, J.M.Hickey, A.Anbanandam, K.Dyer, M.Hammel, P.S.Hefty.

ABSTRACT

ChxR is an atypical two-component signal transduction response regulator (RR) of the OmpR/PhoB subfamily encoded by the obligate intracellular bacterial pathogen Chlamydia trachomatis. Despite structural homology within both receiver and effector domains to prototypical subfamily members, ChxR does not require phosphorylation for dimer formation, DNA binding or transcriptional activation. Thus, we hypothesized that ChxR is in a conformation optimal for DNA binding with limited interdomain interactions. To address this hypothesis, the NMR solution structure of the ChxR effector domain was determined and used in combination with the previously reported ChxR receiver domain structure to generate a full-length dimer model based upon SAXS analysis. Small-angle scattering of ChxR supported a dimer with minimal interdomain interactions and effector domains in a conformation that appears to require only subtle reorientation for optimal major/minor groove DNA interactions. SAXS modeling also supported that the effector domains were in a head-to-tail conformation, consistent with ChxR recognizing tandem DNA repeats. The effector domain structure was leveraged to identify key residues that were critical for maintaining protein - nucleic acid interactions. In combination with prior analysis of the essential location of specific nucleotides for ChxR recognition of DNA, a model of the full-length ChxR dimer bound to its cognate cis-acting element was generated.