ClpXP protease regulates the signal peptide cleavage of secretory preproteins in Bacillus subtilis with a mechanism distinct from that of the Ecs ABC transporter.
Identification and characterization of a suppressor mutation, sup-15, which partially restored secretion in the protein secretion-deficient Bacillus subtilis ecsA26 mutant, led us to discover a novel function of Clp protease. Inactivation of ClpP improved the processing of the precursor of AmyQ alpha-amylase exposed on the outer surface of the cytoplasmic membrane. A similar improvement of AmyQ secretion was conferred by inactivation of the ClpX substrate-binding component of the ClpXP complex. In the absence of ClpXP, the transcription of the sipS, sipT, sipV, and lsp signal peptidase genes was elevated two- to fivefold, a likely cause of the improvement of the processing and secretion of AmyQ and complementation of ecs mutations. Specific overproduction of SipT enhanced the secretion. These findings extend the regulatory roles of ClpXP to protein secretion. ClpXP also influenced the processing of the lipoprotein PrsA. A concerted regulation of signal peptidase genes by a ClpXP-dependent activator is suggested. In contrast, Ecs did not affect transcription of the sip genes, pointing to a different mechanism of secretion regulation.
Pummi
Tiina
T
Vaccine Development Laboratory, National Public Health Institute, FIN-00300 Helsinki, Finland.
Leskelä
Soile
S
Wahlström
Eva
E
Gerth
Ulf
U
Tjalsma
Harold
H
Hecker
Michael
M
Sarvas
Matti
M
Kontinen
Vesa P
VP
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D049071:Endopeptidase Clp; D015870:Gene Expression; D008565:Membrane Proteins; D016296:Mutagenesis; D011498:Protein Precursors / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; C098149:EcsA protein, Bacillus subtilis; D008565:Membrane Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D049071:Endopeptidase Clp; D016282:Aspartic Acid Endopeptidases; C095652:signal peptidase II; D000251:Adenosine Triphosphatases