An analysis of the effect of changes in growth temperature on proteolysis in vivo in the psychrophilic bacterium Vibrio sp. strain ANT-300.
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 protease 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 degrees C after a shift-up from 0 degrees C increased to a level 36% and 17% higher than that of cells grown at 0 degrees C and 13 degrees C, respectively. A shift-down to 0 degrees C from 13 degrees 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 degrees C. There was an increase in ATP-independent protease activity during incubation at temperatures between 25 and 30 degrees C, but a decrease at 35 degrees 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.
Araki
T
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Institute of Low Temperature Science, Hokkaido University, Sapporo, Japan.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D002364:Caseins / Q000378:metabolism; D002455:Cell Division; D002474:Cell-Free System; D003080:Cold Temperature; D003574:Cytochrome c Group / Q000378:metabolism; D010450:Endopeptidases / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D005914:Globins / Q000378:metabolism; D006358:Hot Temperature; D007328:Insulin / Q000378:metabolism; D011480:Protease Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism; D014733:Vibrio / Q000254:growth & development / Q000378:metabolism*
D002364:Caseins; D003574:Cytochrome c Group; D007328:Insulin; D011480:Protease Inhibitors; D011506:Proteins; D000255:Adenosine Triphosphate; D005914:Globins; D010450:Endopeptidases; D012697:Serine Endopeptidases