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91 a.a.
100 a.a.
Key reference
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.
Literature references that cite this PDB file's key reference
PubMed id Reference
18493644 L.Y.Lee, T.Hupfield, R.L.Nicholson, J.T.Hodgkinson, X.Su, G.L.Thomas, G.P.Salmond, M.Welch, and D.R.Spring (2008).
2-Methoxycyclopentyl analogues of a Pseudomonas aeruginosa quorum sensing modulator.Mol Biosyst, 4, 505-507.
17921255 G.Chen, P.D.Jeffrey, C.Fuqua, Y.Shi, and L.Chen (2007).
Structural basis for antiactivation in bacterial quorum sensing.Proc Natl Acad Sci U S A, 104, 16474-16479.
PDB code: 2q0o
16547030 C.Wang, H.B.Zhang, G.Chen, L.Chen, and L.H.Zhang (2006).
Dual control of quorum sensing by two TraM-type antiactivators in Agrobacterium tumefaciens octopine strain A6.J Bacteriol, 188, 2435-2445.
16997969 G.Chen, C.Wang, C.Fuqua, L.H.Zhang, and L.Chen (2006).
Crystal structure and mechanism of TraM2, a second quorum-sensing antiactivator of Agrobacterium tumefaciens strain A6.J Bacteriol, 188, 8244-8251.
PDB code: 2hjd
17158701 J.E.González, and N.D.Keshavan (2006).
Messing with bacterial quorum sensing.Microbiol Mol Biol Rev, 70, 859-875.
16170413 A.B.Goryachev, D.J.Toh, K.B.Wee, T.Lee, H.B.Zhang, and L.H.Zhang (2005).
Transition to quorum sensing in an Agrobacterium population: A stochastic model.PLoS Comput Biol, 1, e37. The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.
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