Life in the cold: a proteomic study of cold-repressed proteins in the antarctic bacterium pseudoalteromonas haloplanktis TAC125

Abstract

The proteomes expressed at 4°C and 18°C by the psychrophilic Antarctic bacterium Pseudoalteromonas haloplanktis were compared using two-dimensional differential in-gel electrophoresis with special reference to proteins repressed by low temperatures. Remarkably, the major cold-repressed proteins, almost undetectable at 4°C, were heat shock proteins involved in folding assistance.

Fig. 1.

(a) Temperature dependence of the generation time of Pseudoalteromonas haloplanktis TAC125 grown in marine broth (solid line and circles). A typical curve for E. coli RR1 in LB broth is shown for comparison (dashed line). (b) Growth curves of P. haloplanktis at 4°C (○), 18°C (●), and 26°C (■).

Fig. 2.

Distribution of the relative abundance of cold-repressed proteins (dashed, negative values, 18°C/4°C spot volume ratio) and of cold acclimation proteins (positive values, 4°C/18°C spot volume ratio) in the proteome of P. haloplanktis grown at 4°C.

Fig. 3.

Comparative analysis of spots containing the chaperone DnaK from Pseudoalteromonas haloplanktis grown at 4°C (left panels) and 18°C (right panels). Spot view on a 2D gel seen in fluorescence (upper panels) and three-dimensional images (lower panels) obtained with DeCyder software.