PDBsum entry 2h99

Transcription

PDB id: 2h99

Contents

Protein chains

215 a.a. *

Ligands

SO4 ×5

ACT ×5

GOL

Metals

_CL

Waters ×578

* Residue conservation analysis

PDB id:

2h99

Name:

Transcription

Title:

Crystal structure of the effector binding domain of a benm variant (r156h,t157s)

Structure:

Hth-type transcriptional regulator benm. Chain: a, b. Fragment: effector binding domain. Synonym: ben and cat operon transcriptional regulator. Engineered: yes. Mutation: yes

Source:

Acinetobacter sp.. Organism_taxid: 62977. Strain: adp1. Gene: benm, benr. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

1.85Å R-factor: 0.167 R-free: 0.204

Authors:

O.C.Ezezika,S.H.Craven,E.L.Neidle,C.Momany

Key ref:

S.H.Craven et al. (2009). Inducer responses of BenM, a LysR-type transcriptional regulator from Acinetobacter baylyi ADP1. Mol Microbiol, 72, 881-894. PubMed id: 19400783

Date:

09-Jun-06 Release date: 26-Jun-07

Protein chains

O68014  (BENM_ACIAD) -  HTH-type transcriptional regulator BenM from Acinetobacter baylyi (strain ATCC 33305 / BD413 / ADP1)

Seq: 304 a.a.

Struc: 215 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Mol Microbiol 72:881-894 (2009)

PubMed id: 19400783

Inducer responses of BenM, a LysR-type transcriptional regulator from Acinetobacter baylyi ADP1.

S.H.Craven, O.C.Ezezika, S.Haddad, R.A.Hall, C.Momany, E.L.Neidle.

ABSTRACT

BenM and CatM control transcription of a complex regulon for aromatic compound degradation. These Acinetobacter baylyi paralogues belong to the largest family of prokaryotic transcriptional regulators, the LysR-type proteins. Whereas BenM activates transcription synergistically in response to two effectors, benzoate and cis,cis-muconate, CatM responds only to cis,cis-muconate. Here, site-directed mutagenesis was used to determine the physiological significance of an unexpected benzoate-binding pocket in BenM discovered during structural studies. Residues in BenM were changed to match those of CatM in this hydrophobic pocket. Two BenM residues, R160 and Y293, were found to mediate the response to benzoate. Additionally, alteration of these residues caused benzoate to inhibit activation by cis,cis-muconate, positioned in a separate primary effector-binding site of BenM. The location of the primary site, in an interdomain cleft, is conserved in diverse LysR-type regulators. To improve understanding of this important family, additional regulatory mutants were analysed. The atomic-level structures were characterized of the effector-binding domains of variants that do not require inducers for activation, CatM(R156H) and BenM(R156H,T157S). These structures clearly resemble those of the wild-type proteins in their activated muconate-bound complexes. Amino acid replacements that enable activation without effectors reside at protein interfaces that may impact transcription through effects on oligomerization.