PDBsum entry 1us6

Transcription repressor

PDB id: 1us6

Contents

Protein chains

91 a.a. *

100 a.a. *

Waters ×217

* Residue conservation analysis

PDB id:

1us6

Name:

Transcription repressor

Title:

Crystal structure of the quorum-sensing protein tram from agrobacterium tumefaciens at 1.65 ang. Resolution

Structure:

Transcriptional repressor tram. Chain: a, b. Synonym: tram. Engineered: yes

Source:

Agrobacterium tumefaciens. Organism_taxid: 358. Expressed in: escherichia coli. Expression_system_taxid: 511693. Other_details: synthetic gene

Biol. unit:

Dimer (from PDB file)

Resolution:

1.65Å R-factor: 0.210 R-free: 0.260

Authors:

A.Vannini,S.Di Marco

Key ref:

A.Vannini et al. (2004). Crystal structure of the quorum-sensing protein TraM and its interaction with the transcriptional regulator TraR. J Biol Chem, 279, 24291-24296. PubMed id: 15044488 DOI: 10.1074/jbc.M401855200

Date:

18-Nov-03 Release date: 25-May-04

Protein chain

Q57471  (TRAM_RHIRD) -  Transcriptional repressor TraM from Rhizobium radiobacter

Seq: 102 a.a.

Struc: 91 a.a.

Protein chain

Q57471  (TRAM_RHIRD) -  Transcriptional repressor TraM from Rhizobium radiobacter

Seq: 102 a.a.

Struc: 100 a.a.

Enzyme reactions

• Enzyme class: Chains A, B: E.C.?

DOI no: 10.1074/jbc.M401855200

J Biol Chem 279:24291-24296 (2004)

PubMed id: 15044488

Crystal structure of the quorum-sensing protein TraM and its interaction with the transcriptional regulator TraR.

A.Vannini, C.Volpari, S.Di Marco.

ABSTRACT

Transfer of the tumor-inducing plasmid in Agrobacterium tumefaciens is controlled by a quorum-sensing system whose main components are the transcriptional regulator TraR and its autoinducer. This system allows bacteria to synchronize infection of the host plant when a "quorum" of cells has been reached. TraM is an A. tumefaciens protein involved in the regulation of this system because it binds to TraR and prevents it from binding DNA. As a first step to understanding the molecular basis for the regulation of TraR by TraM, we have determined the crystal structure of TraM at 1.65 A resolution. This protein is packed as a dimer, with each monomer consisting mainly of two antiparallel alpha helices. Monomers are tightly associated, with a large hydrophobic area buried upon dimerization. Secondly, we characterized the TraR-TraM complex in vitro. TraM (11.4 kDa, monomer molecular mass) binds tightly TraR (27 kDa, monomer molecular mass) forming a stable oligomeric complex that likely accounts for two TraR and two TraM dimers.

Selected figure(s)

Figure 2.
FIG. 2. A, ribbon diagrams of the TraM dimer. Mutants that have demonstrated a reduction in TraR binding efficiency, as well as a loss of activity in vivo, are drawn in stick representation (Leu-29, His-40, Arg-41, Leu-54, Tyr-72, Val-86, Gly-94, and Pro-97). Oxygen, carbon, and nitrogen are colored red, gray, and blue, respectively. Only one monomer is labeled, for clarity. Three orthogonal views are shown. B, molecular surface of the TraM dimer with mutants Leu-29 (orange), His-40 (white), Arg-41 (green), Leu-54 (red), Tyr-72 (blue), Val-86 (cyan), Gly-94 (magenta), and Pro-97 (yellow) mapped on. Only one monomer is labeled, for clarity. Three orthogonal views are shown.

Figure 4.
FIG. 4. A, schematic model of a two-dimers-to-two-dimers TraR-TraM complex. For clarity, just the TraR DNA binding domain (TraR DBD) is depicted. Red arrows represent the 2-fold axes of each TraR and TraM dimer. Two views are shown. B, molecular surface of the hypothetical TraR-TraM complex. The red filled circles indicate the putative position of an N-terminal His tag on TraM.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 24291-24296) copyright 2004.

Figures were selected by the author.