Role of Clp protease subunits in degradation of carbon starvation proteins in Escherichia coli.
When deprived of a carbon source, Escherichia coli induces the synthesis of a group of carbon starvation proteins. The degradation of proteins labeled during starvation was found to be an energy-dependent process which was inhibited by the addition of KCN and accelerated when cells were resupplied with a carbon source. The degradation of the starvation proteins did not require the ATP-dependent Lon protease or the energy-independent proteases protease I, protease IV, OmpT, and DegP. During starvation, mutants lacking either the ClpA or ClpP subunit of the ATP-dependent Clp protease showed a partial reduction in the degradation of starvation proteins. Strains lacking ClpP failed to increase degradation of starvation proteins when glucose was added to starving cells. The clpP mutants showed a competitive disadvantage compared with wild-type cells when exposed to repeated cycles of carbon starvation and growth. Surprisingly, the glucose-stimulated, ClpP-dependent degradation of starvation proteins did not require either the ClpA or ClpB protein. The patterns of synthesis of starvation proteins were similar in clpP+ and clpP cells. The clpP mutants had reduced rates of degradation of certain starvation proteins in the membrane fraction when a carbon source was resupplied to the starved cells.
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Nelson Biology Laboratories, Department of Biological Sciences, Rutgers University, Piscataway, New Jersey 08855-1059.
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D049069:ATP-Dependent Proteases; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D002701:Chloramphenicol / Q000494:pharmacology; D004734:Energy Metabolism; D004790:Enzyme Induction; D004926:Escherichia coli / Q000187:drug effects / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005947:Glucose / Q000172:deficiency / Q000378:metabolism*; D006360:Heat-Shock Proteins; D008565:Membrane Proteins / Q000378:metabolism; D011190:Potassium Cyanide / Q000494:pharmacology; D049070:Protease La; D012641:Selection, Genetic; D012697:Serine Endopeptidases / Q000378:metabolism*; D013997:Time Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D002701:Chloramphenicol; D000255:Adenosine Triphosphate; D049069:ATP-Dependent Proteases; D012697:Serine Endopeptidases; C483567:Lon protein, E coli; D049070:Protease La; D005947:Glucose; D011190:Potassium Cyanide