PDBsum entry: 2vzw

Transferase

PDB id: 2vzw

Contents

Protein chains

146 a.a. *

Ligands

HEM

ACT ×2

HEM-OXY

Waters ×109

* Residue conservation analysis

PDB id:

2vzw

Name:

Transferase

Title:

X-ray structure of the heme-bound gaf domain of sensory histidine kinase dost of mycobacterium tuberculosis

Structure:

Probable histidine kinase response regulator. Chain: a, b. Fragment: gaf sensory domain, residues 61-208. Synonym: gaf family protein, dost. Engineered: yes

Source:

Mycobacterium tuberculosis. Organism_taxid: 83332. Strain: h37rv. Gene: rv2027c. Expressed in: escherichia coli. Expression_system_taxid: 469008.

Resolution:

2.30Å R-factor: 0.239 R-free: 0.289

Authors:

L.M.Podust,A.Ioanoviciu,P.R.Ortiz De Montellano

Key ref:

L.M.Podust et al. (2008). 2.3 A X-ray Structure of the Heme-Bound GAF Domain of Sensory Histidine Kinase DosT of Mycobacterium tuberculosis. Biochemistry, 47, 12523-12531. PubMed id: 18980385 DOI: 10.1021/bi8012356

Date:

06-Aug-08 Release date: 17-Mar-09

Protein chains

O53473  (DOST_MYCTU) -  Hypoxia sensor histidine kinase response regulator dosT

Seq: 573 a.a.

Struc: 146 a.a.*

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

 Gene Ontology (GO) functional annotation 

• Biochemical function: protein binding (1 term)

DOI no: 10.1021/bi8012356

Biochemistry 47:12523-12531 (2008)

PubMed id: 18980385

2.3 A X-ray Structure of the Heme-Bound GAF Domain of Sensory Histidine Kinase DosT of Mycobacterium tuberculosis.

L.M.Podust, A.Ioanoviciu, P.R.Ortiz de Montellano.

ABSTRACT

Mycobacterium tuberculosis responds to changes in environmental conditions through a two-component signaling system that detects reduced O 2 tension and NO and CO exposures via the heme-binding GAF domains of two sensory histidine kinases, DosT and DevS, and the transcriptional regulator DosR. We report the first X-ray structure of the DosT heme-bound GAF domain (GAF DosT) in both oxy and deoxy forms determined to a resolution of 2.3 A. In GAF DosT, heme binds in an orientation orthogonal to that in the PAS domains via a highly conserved motif, including invariant H147 as a proximal heme axial ligand. On the distal side, invariant Y169 forms stacking interactions with the heme with its long axis parallel and the plane of the ring orthogonal to the heme plane. In one of the two protein monomers in an asymmetric unit, O 2 binds as a second axial ligand to the heme iron and is stabilized via a H-bond to the OH group of Y169. The structure reveals two small tunnel-connected cavities and a pore on the protein surface that suggest a potential route for the access of O 2 to the sensing pocket. The limited conformational differences observed between differently heme iron-ligated GAF DosT monomers in the asymmetric unit may result from crystal lattice limitations since atmospheric oxygen binding likely occurs in the crystal as a result of X-ray-induced Fe (3+) photoreduction during diffraction data collection. Determination of the GAF DosT structure sets up a framework in which to address ligand recognition, discrimination, and signal propagation schemes in the heme-based GAF domains of biological sensors.