Synthesis of membrane and periplasmic proteins during starvation of a marine Vibrio sp.

Changes in membrane and periplasmic protein profiles induced by starvation conditions in the marine Vibrio sp. S14 were examined by one-dimensional gel electrophoresis. Analysis by densitometry resolved at least six periplasmic proteins, nine outer membrane proteins, and four cytoplasmic membrane proteins induced at various times during 120 h of nutrient and energy starvation. Eight of these were also synthesized by heat- and/or ethanol-shocked cells. Pulse-labelling indicated that the starvation-induced proteins were not products of degradation, and that their synthesis was differently modulated during starvation. The most pronounced changes occurred during the initial hours of nutrient and energy deprivation. The correlation between the initial changes in protein composition and utilization of the intracellular energy reserve poly-beta-hydroxybutyrate is discussed. The rate of proteolysis during the initial hours of starvation was approximately 16 times greater than that during exponential growth.