PDBsum entry 4zua

Transcription

PDB id: 4zua

Contents

Protein chains

155 a.a.

Waters ×11

PDB id:

4zua

Name:

Transcription

Title:

Crystal structure of the exsa regulatory domain

Structure:

Exoenzyme s synthesis regulatory protein exsa. Chain: a, b. Fragment: unp residues 2-178. Engineered: yes

Source:

Pseudomonas aeruginosa pao1. Organism_taxid: 208964. Strain: atcc 15692 / pao1 / 1c / prs 101 / lmg 12228. Gene: exsa, pa1713. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

2.50Å R-factor: 0.241 R-free: 0.268

Authors:

F.D.Schubot

Key ref:

M.Shrestha et al. (2015). Structural Analysis of the Regulatory Domain of ExsA, a Key Transcriptional Regulator of the Type Three Secretion System in Pseudomonas aeruginosa. Plos One, 10, e0136533. PubMed id: 26317977 DOI: 10.1371/journal.pone.0136533

Date:

15-May-15 Release date: 03-Feb-16

Protein chains

P26993  (EXSA_PSEAE) -  HTH-type transcriptional regulator ExsA from Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1)

Seq: 278 a.a.

Struc: 155 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1371/journal.pone.0136533

Plos One 10:e0136533 (2015)

PubMed id: 26317977

Structural Analysis of the Regulatory Domain of ExsA, a Key Transcriptional Regulator of the Type Three Secretion System in Pseudomonas aeruginosa.

M.Shrestha, Y.Xiao, H.Robinson, F.D.Schubot.

ABSTRACT

Pseudomonas aeruginosa employs a type three secretion system to facilitate infections in mammalian hosts. The operons encoding genes of structural components of the secretion machinery and associated virulence factors are all under the control of the AraC-type transcriptional activator protein, ExsA. ExsA belongs to a unique subfamily of AraC-proteins that is regulated through protein-protein contacts rather than small molecule ligands. Prior to infection, ExsA is inhibited through a direct interaction with the anti-activator ExsD. To activate ExsA upon host cell contact this interaction is disrupted by the anti-antiactivator protein ExsC. Here we report the crystal structure of the regulatory domain of ExsA, which is known to mediate ExsA dimerization as well as ExsD binding. The crystal structure suggests two models for the ExsA dimer. Both models confirmed the previously shown involvement of helix α-3 in ExsA dimerization but one also suggest a role for helix α-2. These structural data are supported by the observation that a mutation in α-2 greatly diminished the ability of ExsA to activate transcription in vitro. Additional in vitro transcription studies revealed that a conserved pocket, used by AraC and the related ToxT protein for the binding of small molecule regulators, although present in ExsA is not involved in binding of ExsD.