PDBsum entry 3q7t

Transcription

PDB id: 3q7t

Contents

Protein chains

96 a.a.

100 a.a.

Metals

_NA ×2

Waters ×41

PDB id:

3q7t

Name:

Transcription

Title:

2.15a resolution structure (i41 form) of the chxr receiver domain from chlamydia trachomatis

Structure:

Transcriptional regulatory protein. Chain: a, b. Fragment: unp residues 2-113. Engineered: yes

Source:

Chlamydia trachomatis. Organism_taxid: 471472. Strain: 434/bu. Gene: ctlon_0888. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.15Å R-factor: 0.207 R-free: 0.247

Authors:

J.Hickey,S.Lovell,K.P.Battaile,L.Hu,C.R.Middaugh,P.S.Hefty

Key ref:

J.M.Hickey et al. (2011). The atypical response regulator protein ChxR has structural characteristics and dimer interface interactions that are unique within the OmpR/PhoB subfamily. J Biol Chem, 286, 32606-32616. PubMed id: 21775428 DOI: 10.1074/jbc.M111.220574

Date:

05-Jan-11 Release date: 20-Jul-11

Protein chain

A0A0H3MDW1  (CHXR_CHLT2) -  Atypical response regulator protein ChxR from Chlamydia trachomatis serovar L2 (strain 434/Bu / ATCC VR-902B)

Seq: 227 a.a.

Struc: 96 a.a.

Protein chain

A0A0H3MDW1  (CHXR_CHLT2) -  Atypical response regulator protein ChxR from Chlamydia trachomatis serovar L2 (strain 434/Bu / ATCC VR-902B)

Seq: 227 a.a.

Struc: 100 a.a.

Enzyme reactions

• Enzyme class: Chains A, B: E.C.?

DOI no: 10.1074/jbc.M111.220574

J Biol Chem 286:32606-32616 (2011)

PubMed id: 21775428

The atypical response regulator protein ChxR has structural characteristics and dimer interface interactions that are unique within the OmpR/PhoB subfamily.

J.M.Hickey, S.Lovell, K.P.Battaile, L.Hu, C.R.Middaugh, P.S.Hefty.

ABSTRACT

Typically as a result of phosphorylation, OmpR/PhoB response regulators form homodimers through a receiver domain as an integral step in transcriptional activation. Phosphorylation stabilizes the ionic and hydrophobic interactions between monomers. Recent studies have shown that some response regulators retain functional activity in the absence of phosphorylation and are termed atypical response regulators. The two currently available receiver domain structures of atypical response regulators are very similar to their phospho-accepting homologs, and their propensity to form homodimers is generally retained. An atypical response regulator, ChxR, from Chlamydia trachomatis, was previously reported to form homodimers; however, the residues critical to this interaction have not been elucidated. We hypothesize that the intra- and intermolecular interactions involved in forming a transcriptionally competent ChxR are distinct from the canonical phosphorylation (activation) paradigm in the OmpR/PhoB response regulator subfamily. To test this hypothesis, structural and functional studies were performed on the receiver domain of ChxR. Two crystal structures of the receiver domain were solved with the recently developed method using triiodo compound I3C. These structures revealed many characteristics unique to OmpR/PhoB subfamily members: typical or atypical. Included was the absence of two α-helices present in all other OmpR/PhoB response regulators. Functional studies on various dimer interface residues demonstrated that ChxR forms relatively stable homodimers through hydrophobic interactions, and disruption of these can be accomplished with the introduction of a charged residue within the dimer interface. A gel shift study with monomeric ChxR supports that dimerization through the receiver domain is critical for interaction with DNA.