2hp7
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(New page: 200px<br /><applet load="2hp7" size="350" color="white" frame="true" align="right" spinBox="true" caption="2hp7, resolution 2.00Å" /> '''Structure of FliM pr...)
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Revision as of 18:25, 29 January 2008
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Structure of FliM provides insight into assembly of the switch complex in the bacterial flagella motor
Overview
Bacteria switch the direction their flagella rotate to control movement., FliM, along with FliN and FliG, compose a complex in the motor that, upon, binding phosphorylated CheY, reverses the sense of flagellar rotation. The, 2.0-A resolution structure of the FliM middle domain (FliM(M)) from, Thermotoga maritima reveals a pseudo-2-fold symmetric topology similar to, the CheY phosphatases CheC and CheX. A variable structural element, which, in CheC, mediates binding to CheD (alpha2') and, in CheX, mediates, dimerization (beta'(x)), has a truncated structure unique to FliM, (alpha2'). An exposed helix of FliM(M) (alpha1) does not contain the, catalytic residues of CheC and CheX but does include positions conserved, in FliM sequences. Cross-linking experiments with site-directed cysteine, mutants show that FliM self-associates through residues on alpha1 and, alpha2'. CheY activated by BeF(3)(-) binds to FliM with approximately, 40-fold higher affinity than CheY (K(d) = 0.04 microM vs. 2 microM)., Mapping residue conservation, suppressor mutation sites, binding data, and, deletion analysis onto the FliM(M) surface defines regions important for, contacts with the stator-interacting protein FliG and for either, counterclockwise or clockwise rotation. Association of 33-35 FliM subunits, would generate a 44- to 45-nm-diameter disk, consistent with the known, dimensions of the C-ring. The localization of counterclockwise- and, clockwise-biasing mutations to distinct surfaces suggests that the binding, of phosphorylated CheY cooperatively realigns FliM around the ring.
About this Structure
2HP7 is a Single protein structure of sequence from Thermotoga maritima. Full crystallographic information is available from OCA.
Reference
Structure of FliM provides insight into assembly of the switch complex in the bacterial flagella motor., Park SY, Lowder B, Bilwes AM, Blair DF, Crane BR, Proc Natl Acad Sci U S A. 2006 Aug 8;103(32):11886-91. Epub 2006 Aug 1. PMID:16882724
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