title: Discovery of a Unique Clp Component, ClpF, in Chloroplasts: A Proposed Binary ClpF-ClpS1 Adaptor Complex Functions in Substrate Recognition and Delivery.
abstract: Clp proteases are found in prokaryotes, mitochondria, and plastids where they play crucial roles in maintaining protein homeostasis (proteostasis). The plant plastid Clp machinery comprises a hetero-oligomeric ClpPRT proteolytic core, ATP-dependent chaperones ClpC and ClpD, and an adaptor protein, ClpS1. ClpS1 selects substrates to the ClpPR protease-ClpC chaperone complex for degradation, but the underlying substrate recognition and delivery mechanisms are currently unclear. Here, we characterize a ClpS1-interacting protein in Arabidopsis thaliana, ClpF, which can interact with the Clp substrate glutamyl-tRNA reductase. ClpF and ClpS1 mutually stimulate their association with ClpC. ClpF, which is only found in photosynthetic eukaryotes, contains bacterial uvrB/C and YccV protein domains and a unique N-terminal domain. We propose a testable model in which ClpS1 and ClpF form a binary adaptor for selective substrate recognition and delivery to ClpC, reflecting an evolutionary adaptation of the Clp system to the plastid proteome.
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853.
authors.forename: Kenji
authors.initials: K
authors.lastname: Nishimura
authors.affiliation: Department of Plant Physiology, Humboldt University, 10115 Berlin, Germany.
authors.forename: Janina
authors.initials: J
authors.lastname: Apitz
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853.
authors.forename: Giulia
authors.initials: G
authors.lastname: Friso
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853.
authors.forename: Jitae
authors.initials: J
authors.lastname: Kim
authors.affiliation: Computational Biology Service Unit, Cornell University, Ithaca, New York 14853.
authors.forename: Lalit
authors.initials: L
authors.lastname: Ponnala
authors.affiliation: Department of Plant Physiology, Humboldt University, 10115 Berlin, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Grimm
authors.affiliation: Department of Plant Biology, Cornell University, Ithaca, New York 14853 kv35@cornell.edu.
authors.forename: Klaas J
authors.identifier: http://orcid.org/0000-0001-9536-0487
authors.initials: KJ
authors.lastname: van Wijk
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000445:Aldehyde Oxidoreductases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000201:enzymology; D049071:Endopeptidase Clp / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009097:Multienzyme Complexes; D009154:Mutation; D010802:Phylogeny; D025941:Protein Interaction Mapping; D020543:Proteome; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; C000622187:ClpF protein, Arabidopsis; C000622188:ClpS1 protein, Arabidopsis; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D020543:Proteome; D000445:Aldehyde Oxidoreductases; C067282:glutamyl tRNA reductase; D049071:Endopeptidase Clp