National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM-101988
米国
Howard Hughes Medical Institute (HHMI)
米国
引用
ジャーナル: Elife / 年: 2020 タイトル: Structures of the ATP-fueled ClpXP proteolytic machine bound to protein substrate. 著者: Xue Fei / Tristan A Bell / Simon Jenni / Benjamin M Stinson / Tania A Baker / Stephen C Harrison / Robert T Sauer / 要旨: ClpXP is an ATP-dependent protease in which the ClpX AAA+ motor binds, unfolds, and translocates specific protein substrates into the degradation chamber of ClpP. We present cryo-EM studies of the ...ClpXP is an ATP-dependent protease in which the ClpX AAA+ motor binds, unfolds, and translocates specific protein substrates into the degradation chamber of ClpP. We present cryo-EM studies of the enzyme that show how asymmetric hexameric rings of ClpX bind symmetric heptameric rings of ClpP and interact with protein substrates. Subunits in the ClpX hexamer assume a spiral conformation and interact with two-residue segments of substrate in the axial channel, as observed for other AAA+ proteases and protein-remodeling machines. Strictly sequential models of ATP hydrolysis and a power stroke that moves two residues of the substrate per translocation step have been inferred from these structural features for other AAA+ unfoldases, but biochemical and single-molecule biophysical studies indicate that ClpXP operates by a probabilistic mechanism in which five to eight residues are translocated for each ATP hydrolyzed. We propose structure-based models that could account for the functional results.