RT Journal Article SR Electronic(1) A1 Araki, TadashiYR 1992 T1 An analysis of the effect of changes in growth temperature on proteolysis in vivo in the psychrophilic bacterium Vibrio sp. strain ANT-300 JF Microbiology, VO 138 IS 10 SP 2075 OP 2082 DO https://doi.org/10.1099/00221287-138-10-2075 PB Microbiology Society, SN 1465-2080, AB In the psychrophilic bacterium Vibrio sp. strain ANT-300, the rate of protein degradation in vivo, measured at fixed temperatures, increased with elevation of the growth temperature. A shift in growth temperature induced a marked increase in this rate. Dialysed cell-free extracts hydrolysed exogenous insulin, globin and casein (in decreasing order of activity) but did not hydrolyse exogenous cytochrome c. Cells contained at least seven proteases separated by DEAE-Sephacel chromatography, one of which was an ATP-dependent serine protease. The ATP-dependent proteolytic activity in extracts of cells incubated for 3 h at 16 °C after a shift-up from 0 °C increased to a level 36% and 17% higher than that of cells grown at 0 °C and 13 °C, respectively. A shift-down to 0 °C from 13 °C induced only a slight increase in the proteolytic activity. Extracts of all cells, whether exposed to temperature shifts or not, showed the same temperature dependence with respect to both ATP-dependent and ATP-independent protease activity. In all the extracts these proteases also exhibited the same heat lability. The ATP-dependent protease was inactivated by incubation at temperatures above 25 °C. There was an increase in ATP-independent protease activity during incubation at temperatures between 25 and 30 °C, but a decrease at 35 °C and higher. These results suggest that the marked increases in proteolysis in vivo, caused by a shift in temperature, may result not only from increases in levels of ATP-dependent serine protease(s) but also from increases in the susceptibility of proteins to degradation., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-138-10-2075