title: Communication between ClpX and ClpP during substrate processing and degradation.
abstract: 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.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA.
authors.forename: Shilpa A
authors.initials: SA
authors.lastname: Joshi
authors.forename: Greg L
authors.initials: GL
authors.lastname: Hersch
authors.forename: Tania A
authors.initials: TA
authors.lastname: Baker
authors.forename: Robert T
authors.initials: RT
authors.lastname: Sauer
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D000595:Amino Acid Sequence; D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
chemical_list: D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D012697:Serine Endopeptidases; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities