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Nat Struct Mol Biol. 2004 May;11(5):404-11. Epub 2004 Apr 4.

Communication between ClpX and ClpP during substrate processing and degradation.

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Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.


In the ClpXP compartmental protease, ring hexamers of the AAA(+) ClpX ATPase bind, denature and then translocate protein substrates into the degradation chamber of the double-ring ClpP(14) peptidase. A key question is the extent to which functional communication between ClpX and ClpP occurs and is regulated during substrate processing. Here, we show that ClpX-ClpP affinity varies with the protein-processing task of ClpX and with the catalytic engagement of the active sites of ClpP. Functional communication between symmetry-mismatched ClpXP rings depends on the ATPase activity of ClpX and seems to be transmitted through structural changes in its IGF loops, which contact ClpP. A conserved arginine in the sensor II helix of ClpX links the nucleotide state of ClpX to the binding of ClpP and protein substrates. A simple model explains the observed relationships between ATP binding, ATP hydrolysis and functional interactions between ClpX, protein substrates and ClpP.

[Indexed for MEDLINE]

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