title: A Phosphosignaling Adaptor Primes the AAA+ Protease ClpXP to Drive Cell Cycle-Regulated Proteolysis.
abstract: The response regulator CpdR couples phosphorylation events in Caulobacter crescentus with the AAA+ protease ClpXP to provide punctuated degradation of crucial substrates involved in cell cycle regulation. CpdR functions like an adaptor to alter substrate choice by ClpXP; however, it remains unclear how CpdR influences its multiple targets. Here we show that, unlike canonical ClpXP adaptors, CpdR alone does not strongly bind its substrate. Instead, CpdR binds the N-terminal domain of ClpX and prepares (primes) the unfoldase for substrate engagement. This priming creates a recruitment interface that docks multiple substrates and additional adaptor components. We show that adaptor-dependent priming of ClpX avoids concentration-dependent inhibition that limits traditional scaffolding adaptors. Phosphosignaling disrupts the adaptor-protease interaction, and mutations in CpdR that impact ClpX binding tune adaptor activity and biological function. Together, these results reveal how a single adaptor can command global changes in proteome composition through priming of a protease.
authors.affiliation: Microbiology Graduate Program, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
authors.forename: Joanne
authors.initials: J
authors.lastname: Lau
authors.affiliation: Molecular and Cellular Biology Graduate Program, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hernandez-Alicea
authors.affiliation: Molecular and Cellular Biology Graduate Program, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Vass
authors.affiliation: Microbiology Graduate Program, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA; Molecular and Cellular Biology Graduate Program, Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA. Electronic address: pchien@biochem.umass.edu.
authors.forename: Peter
authors.initials: P
authors.lastname: Chien
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D016935:Caulobacter crescentus / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics*; D059447:Cell Cycle Checkpoints / Q000235:genetics; D049071:Endopeptidase Clp / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D059748:Proteolysis
chemical_list: D001426:Bacterial Proteins; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases