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  • Title: Conformational plasticity of the ClpAP AAA+ protease couples protein unfolding and proteolysis.
    Author: Lopez KE, Rizo AN, Tse E, Lin J, Scull NW, Thwin AC, Lucius AL, Shorter J, Southworth DR.
    Journal: Nat Struct Mol Biol; 2020 May; 27(5):406-416. PubMed ID: 32313240.
    Abstract:
    The ClpAP complex is a conserved bacterial protease that unfolds and degrades proteins targeted for destruction. The ClpA double-ring hexamer powers substrate unfolding and translocation into the ClpP proteolytic chamber. Here, we determined high-resolution structures of wild-type Escherichia coli ClpAP undergoing active substrate unfolding and proteolysis. A spiral of pore loop-substrate contacts spans both ClpA AAA+ domains. Protomers at the spiral seam undergo nucleotide-specific rearrangements, supporting substrate translocation. IGL loops extend flexibly to bind the planar, heptameric ClpP surface with the empty, symmetry-mismatched IGL pocket maintained at the seam. Three different structures identify a binding-pocket switch by the IGL loop of the lowest positioned protomer, involving release and re-engagement with the clockwise pocket. This switch is coupled to a ClpA rotation and a network of conformational changes across the seam, suggesting that ClpA can rotate around the ClpP apical surface during processive steps of translocation and proteolysis.
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