Proteomics of life at low temperatures: trigger factor is the primary chaperone in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125

Abstract

SummaryThe proteomes expressed at 4°C and 18°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°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°C. The recombinant psychrophilic trigger factor is a monomer that displays unusually low conformational stability with a Tm value of 33°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 temperaturedependent and requires near-zero temperature to stably bind a model-unfolded polypeptide.

Strategies for the production of difficult-to-express full-length eukaryotic proteins using microbial cell factories: production of human alpha-galactosidase A

“…The system has demonstrated to be especially useful in improving protein 77 solubility in relation to the widely used E. coli expression system and gives higher protein yield for secreted 78 proteins (Cusano et al, 2006;Giuliani et al, 2014;Vigentini et al, 2006). Proteomics analysis point out the 79 triger factor chaperone as the main factor involved in protein folding during recombinant protein expression 80 under cold temperatures (Piette et al, 2010). 81…”

Life in the Cold: Proteomics of the Antarctic Bacterium Pseudoalteromonas haloplanktis

“…From top to bottom, mass scale from ~150 to ~15 kDa. The intense red fluorescence of the trigger factor (TF) spot correlates with its upregulation at 4°C, whereas the intense green fluorescence of the DnaK spot correlates with its down-regulation Adapted with permission from Piette et al, 2010. © 2010 In a typical single 2D-gel (Fig.…”

“…However, about 20% of these differentially expressed proteins display up-or down-regulation factors higher than 5, revealing that some key cellular functions are strongly regulated. Amongst all these differentially expressed proteins, 40 CAPs and 83 CRPs were retained, which satisfied both statistical biological variation analysis and mass spectrometry identification scores, as detailed in the original publications (Piette et al, 2010;Piette et al, 2011). Accordingly, the identified proteins should be analyzed as markers of a pathway or of a general function, rather than for their specific function as they represent 27% of the differentially expressed proteins at 4°C.…”

“…This work has allowed a proteomic study of its cold-acclimation proteins (CAPs) 1 , i.e. proteins that are continuously overexpressed at a high level during growth at low temperatures (Piette et al, 2010). This has demonstrated that protein synthesis and protein folding are the main up-regulated functions, suggesting that both cellular processes are limiting factors for bacterial development in cold environments.…”

“…More recently, several genomes from psychrophilic bacteria have been sequenced (Danchin, 2007;Casanueva et al, 2010) but only a few of them have been analyzed with respect to cold adaptation (Saunders et al, 2003;Rabus et al, 2004;Medigue et al, 2005;Methe et al, 2005;Riley et al, 2008;Allen et al, 2009;Ayala-del-Rio et al, 2010). However, the lack of common features shared by all these psychrophilic genomes has suggested that cold adaptation superimposes on pre-existing cellular organization and, accordingly, that the adaptive strategies may differ between the various microorganisms (Bowman, 2008;Piette et al, 2010). The Gram-negative bacterium Pseudoalteromonas haloplanktis is a typical representative of γ-proteobacteria found in cold marine environments and, in fact, strain TAC125 has been isolated from sea water sampled along the Antarctic ice-shell (Terre Adélie).…”