title: Chaperone networking facilitates protein targeting to the bacterial cytoplasmic membrane.
abstract: Nascent polypeptides emerging from the ribosome are assisted by a pool of molecular chaperones and targeting factors, which enable them to efficiently partition as cytosolic, integral membrane or exported proteins. Extensive genetic and biochemical analyses have significantly expanded our knowledge of chaperone tasking throughout this process. In bacteria, it is known that the folding of newly-synthesized cytosolic proteins is mainly orchestrated by three highly conserved molecular chaperones, namely Trigger Factor (TF), DnaK (HSP70) and GroEL (HSP60). Yet, it has been reported that these major chaperones are strongly involved in protein translocation pathways as well. This review describes such essential molecular chaperone functions, with emphasis on both the biogenesis of inner membrane proteins and the post-translational targeting of presecretory proteins to the Sec and the twin-arginine translocation (Tat) pathways. Critical interplay between TF, DnaK, GroEL and other molecular chaperones and targeting factors, including SecB, SecA, the signal recognition particle (SRP) and the redox enzyme maturation proteins (REMPs) is also discussed. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
authors.affiliation: Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Castanié-Cornet
authors.affiliation: Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bruel
authors.affiliation: Laboratoire de Microbiologie et Génétique Moléculaire (LMGM), Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier, Toulouse, France. Electronic address: Pierre.Genevaux@ibcg.biotoul.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Genevaux
mesh_terms: D001419:Bacteria / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000378:metabolism*; D010084:Oxidation-Reduction; D021381:Protein Transport; D018271:Signal Recognition Particle / Q000378:metabolism
chemical_list: D018834:Chaperonin 60; D018840:HSP70 Heat-Shock Proteins; D018832:Molecular Chaperones; D018271:Signal Recognition Particle
keywords: DnaJ/Hsp40; DnaK/Hsp70; GroEL/Hsp60; Protein targeting pathway; SecA–SecB; Trigger Factor