Signal peptide peptidase- and ClpP-like proteins of Bacillus subtilis required for efficient translocation and processing of secretory proteins.
Signal peptides direct the export of secretory proteins from the cytoplasm. After processing by signal peptidase, they are degraded in the membrane and cytoplasm. The resulting fragments can have signaling functions. These observations suggest important roles for signal peptide peptidases. The present studies show that the Gram-positive eubacterium Bacillus subtilis contains two genes for proteins, denoted SppA and TepA, with similarity to the signal peptide peptidase A of Escherichia coli. Notably, TepA also shows similarity to ClpP proteases. SppA of B. subtilis was only required for efficient processing of pre-proteins under conditions of hyper-secretion. In contrast, TepA depletion had a strong effect on pre-protein translocation across the membrane and subsequent processing, not only under conditions of hyper-secretion. Unlike SppA, which is a typical membrane protein, TepA appears to have a cytosolic localization, which is consistent with the observation that TepA is involved in early stages of the secretion process. Our observations demonstrate that SppA and TepA have a role in protein secretion in B. subtilis. Based on their similarity to known proteases, it seems likely that SppA and TepA are specifically required for the degradation of proteins or (signal) peptides that are inhibitory to protein translocation.
Bolhuis
A
A
Department of Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, Kerklaan 30, 9751 NN Haren, The Netherlands.
Matzen
A
A
Hyyryläinen
H L
HL
Kontinen
V P
VP
Meima
R
R
Chapuis
J
J
Venema
G
G
Bron
S
S
Freudl
R
R
van Dijl
J M
JM
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins; D017124:Conserved Sequence; D003600:Cytosol / Q000201:enzymology; D049071:Endopeptidase Clp; D010450:Endopeptidases / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D010447:Peptide Hydrolases / Q000235:genetics* / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D021382:Protein Sorting Signals / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic; D000516:alpha-Amylases / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D011498:Protein Precursors; D021382:Protein Sorting Signals; C078167:OMPA outer membrane proteins; D000516:alpha-Amylases; D010450:Endopeptidases; D010447:Peptide Hydrolases; D012697:Serine Endopeptidases; C121371:TepA protein, Bacillus subtilis; D049071:Endopeptidase Clp; C030732:protease IV; D000251:Adenosine Triphosphatases