Nature Structural & Molecular Biology11, 404 - 411 (2004)
Published online: 4 April 2004; | doi:10.1038/nsmb752
Communication between ClpX and ClpP during substrate processing and degradation
Shilpa A Joshi1, Greg L Hersch1, Tania A Baker1, 2
& Robert T Sauer1
1
Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
2
Howard Hughes Medical Institute, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
Correspondence should be addressed to Robert T Sauer bobsauer@mit.edu
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 ClpP14 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.
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