Cold shock proteins and cold acclimation proteins in a psychrotrophic bacterium

Abstract

The synthesis of proteins in the psychrotrophic bacterium Bacillus psychrophilus in response to both cold shock and continuous growth at low temperatures was examined. Cold shocks of 20 to 0, 5, or 10 °C resulted in the induction of nine, seven, and five cold shock proteins, respectively, as determined by 2-dimensional gel electrophoresis and computing scanning laser densitometry. Two cold shock proteins, with molecular masses of 61 and 34 kDa, which were induced in B. psychrophilus by cold shocks of 20 to 0 or 5 °C, were not induced in a cold-sensitive mutant of B. psychrophilus. Analysis of protein profiles of B. psychrophilus during continuous growth at 0, 5, or 10 °C revealed the synthesis of 11, 10, and 4 cold acclimation proteins, respectively. Some of these cold acclimation proteins were similar to cold shock proteins. In addition, the relative synthesis of both cold shock proteins and cold acclimation proteins increased with decreasing temperature. Thus, both types of proteins increased both in number and relative synthesis in response to cold shock and continuous growth at low temperature. Key words: cold shock proteins, cold acclimation proteins, psychrotrophic bacterium.