Fine-tuning in regulation of Clp protein content in Bacillus subtilis.
Clp-controlled proteolysis in Bacillus subtilis seems to play a substantial role, particularly under stress conditions. Calibrated Western blot analyses were used to estimate the approximate numbers of heat-inducible Clp molecules within a single cell. According to these numbers, the different Clp ATPases do not seem to compete for the proteolytic subunit ClpP. Coimmunoprecipitation experiments revealed the predicted specific ClpX-ClpP, ClpC-ClpP, and ClpE-ClpP interactions. ClpE and ClpX are rapidly degraded in wild-type cells during permanent heat stress but remained almost stable in a clpP mutant, suggesting ClpP-dependent degradation. In particular, ClpCP appeared to be involved in the degradation of the short-lived ClpE ATPase, indicating a negative "autoregulatory" circuit for this particular Clp ATPase at the posttranslational level. Analysis of the half-life of stress-inducible clp mRNAs during exponential growth and heat shock revealed precise regulation of the synthesis of each Clp protein at the posttranscriptional level as well to meet the needs of B. subtilis.
Gerth
Ulf
U
Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität, D-17487 Greifswald, Germany. Ulf.Gerth@biologie.uni-greifswald.de
Kirstein
Janine
J
Mostertz
Jörg
J
Waldminghaus
Torsten
T
Miethke
Marcus
M
Kock
Holger
H
Hecker
Michael
M
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D018869:Heat-Shock Response; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D012323:RNA Processing, Post-Transcriptional; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D000251:Adenosine Triphosphatases