4i4l
From Proteopedia
Crystal Structure of Nucleotide-Bound W-W-W ClpX Hexamer
Structural highlights
FunctionCLPX_ECOLI ATP-dependent specificity component of the Clp protease. It directs the protease to specific substrates. It may bind to the lambda O substrate protein and present it to the ClpP protease in a form that can be recognized and readily hydrolyzed by ClpP. Can perform chaperone functions in the absence of ClpP.[HAMAP-Rule:MF_00175] Publication Abstract from PubMedClpX, a AAA+ ring homohexamer, uses the energy of ATP binding and hydrolysis to power conformational changes that unfold and translocate target proteins into the ClpP peptidase for degradation. In multiple crystal structures, some ClpX subunits adopt nucleotide-loadable conformations, others adopt unloadable conformations, and each conformational class exhibits substantial variability. Using mutagenesis of individual subunits in covalently tethered hexamers together with fluorescence methods to assay the conformations and nucleotide-binding properties of these subunits, we demonstrate that dynamic interconversion between loadable and unloadable conformations is required to couple ATP hydrolysis by ClpX to mechanical work. ATP binding to different classes of subunits initially drives staged allosteric changes, which set the conformation of the ring to allow hydrolysis and linked mechanical steps. Subunit switching between loadable and unloadable conformations subsequently isomerizes or resets the configuration of the nucleotide-loaded ring and is required for mechanical function. Nucleotide Binding and Conformational Switching in the Hexameric Ring of a AAA+ Machine.,Stinson BM, Nager AR, Glynn SE, Schmitz KR, Baker TA, Sauer RT Cell. 2013 Apr 25;153(3):628-39. doi: 10.1016/j.cell.2013.03.029. PMID:23622246[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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