title: Proteomics of life at low temperatures: trigger factor is the primary chaperone in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125.
abstract: The proteomes expressed at 4 degrees C and 18 degrees C by the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis have been compared using two-dimensional differential in-gel electrophoresis, showing that translation, protein folding, membrane integrity and anti-oxidant activities are upregulated at 4 degrees C. This proteomic analysis revealed that the trigger factor is the main upregulated protein at low temperature. The trigger factor is the first molecular chaperone interacting with virtually all newly synthesized polypeptides on the ribosome and also possesses a peptidyl-prolyl cis-trans isomerase activity. This suggests that protein folding at low temperatures is a rate-limiting step for bacterial growth in cold environments. It is proposed that the psychrophilic trigger factor rescues the chaperone function as both DnaK and GroEL (the major bacterial chaperones but also heat-shock proteins) are downregulated at 4 degrees C. The recombinant psychrophilic trigger factor is a monomer that displays unusually low conformational stability with a Tm value of 33 degrees C, suggesting that the essential chaperone function requires considerable flexibility and dynamics to compensate for the reduction of molecular motions at freezing temperatures. Its chaperone activity is strongly temperature-dependent and requires near-zero temperature to stably bind a model-unfolded polypeptide.
authors.affiliation: Laboratory of Biochemistry, Center for Protein Engineering, University of Liège, Liège, Belgium.
authors.forename: Florence
authors.initials: F
authors.lastname: Piette
authors.forename: Salvino
authors.initials: S
authors.lastname: D'Amico
authors.forename: Caroline
authors.initials: C
authors.lastname: Struvay
authors.forename: Gabriel
authors.initials: G
authors.lastname: Mazzucchelli
authors.forename: Jenny
authors.initials: J
authors.lastname: Renaut
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Tutino
authors.forename: Antoine
authors.initials: A
authors.lastname: Danchin
authors.forename: Pierre
authors.initials: P
authors.lastname: Leprince
authors.forename: Georges
authors.initials: G
authors.lastname: Feller
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis*; D003080:Cold Temperature; D015180:Electrophoresis, Gel, Two-Dimensional; D007700:Kinetics; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D019696:Peptidylprolyl Isomerase / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D055550:Protein Stability; D020543:Proteome / Q000032:analysis*; D031161:Pseudoalteromonas / Q000737:chemistry* / Q000528:radiation effects*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D018832:Molecular Chaperones; D020543:Proteome; D011994:Recombinant Proteins; D019696:Peptidylprolyl Isomerase