Protein turnover in the extreme thermophile Thermus aquaticus

Abstract

Protein turnover in the extreme bacterial thermophile T. aquaticus was examined in exponential cultures at 75.degree. C. The relative amount of [3H]leucine incorporated into trichloroacetic acid-insoluble material was stable in pulse-chase experiments assayed over 2.5 h. The trichloroacetic acid-insoluble radioactive leucine was stable on addition of chloramphenicol, which blocks protein synthesis in T. aquaticus. Specific activity of a phosphate-repressible alkaline phosphatase, investigated in the presence of chloramphenicol, did not decrease. Addition of excess Pi to cultures depressed for the alkaline phosphatase did not show a marked effect on specific activity over a 2-h period. On the basis of these 4 experiments, a high protein turnover rate may not be essential for thermophily of T. aquaticus at 75.degree. C.