Selective Contribution of the Twin-Arginine Translocation Pathway to Protein Secretion in Bacillus subtilis

Abstract

The availability of the complete genome sequence of Bacillus subtilis has allowed the prediction of all exported proteins of this Gram-positive eubacterium. Recently, ∼180 secretory and 114 lipoprotein signal peptides were predicted to direct protein export from the cytoplasm. Whereas most exported proteins appear to use the Sec pathway, 69 of these proteins could potentially use the Tat pathway, as their signal peptides contain RR- or KR-motifs. In the present studies, proteomic techniques were applied to verify how many extracellular B. subtilis proteins follow the Tat pathway. Strikingly, the extracellular accumulation of 13 proteins with potential RR/KR-signal peptides was Tat-independent, showing that their RR/KR-motifs are not recognized by the Tat machinery. In fact, only the phosphodiesterase PhoD was shown to be secreted in a strictly Tat-dependent manner. Sodium azide-inhibition of SecA strongly affected the extracellular appearance of de novosynthesized proteins, including the lipase LipA and two other proteins with predicted RR/KR-signal peptides. The SecA-dependent export of pre-LipA is particularly remarkable, because its RR-signal peptide conforms well to stringent criteria for the prediction of Tat-dependent export in Escherichia coli. Taken together, our observations show that the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis. The availability of the complete genome sequence of Bacillus subtilis has allowed the prediction of all exported proteins of this Gram-positive eubacterium. Recently, ∼180 secretory and 114 lipoprotein signal peptides were predicted to direct protein export from the cytoplasm. Whereas most exported proteins appear to use the Sec pathway, 69 of these proteins could potentially use the Tat pathway, as their signal peptides contain RR- or KR-motifs. In the present studies, proteomic techniques were applied to verify how many extracellular B. subtilis proteins follow the Tat pathway. Strikingly, the extracellular accumulation of 13 proteins with potential RR/KR-signal peptides was Tat-independent, showing that their RR/KR-motifs are not recognized by the Tat machinery. In fact, only the phosphodiesterase PhoD was shown to be secreted in a strictly Tat-dependent manner. Sodium azide-inhibition of SecA strongly affected the extracellular appearance of de novosynthesized proteins, including the lipase LipA and two other proteins with predicted RR/KR-signal peptides. The SecA-dependent export of pre-LipA is particularly remarkable, because its RR-signal peptide conforms well to stringent criteria for the prediction of Tat-dependent export in Escherichia coli. Taken together, our observations show that the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis. The Gram-positive soil bacterium Bacillus subtilis, is well known for its ability to secrete a large variety of proteins into its extracellular environment. Based on the complete genome sequence (1Kunst F. Ogasawara N. Moszer I. Albertini A.M. Alloni G. Azevedo V. Bertero M.G. Bessieres P. Bolotin A. Borchert S. et al.Nature. 1997; 390: 249-256Crossref PubMed Scopus (3102) Google Scholar), it was recently predicted that the extracellular proteome of this organism is composed of ∼180 different proteins (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, a that extracellular proteins be different proteins were H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google it is not known to of the known protein export to the of the extracellular for protein export are known to be present subtilis. by the of their signal the of secretory proteins has the potential to be exported from the the Sec pathway (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, In this pathway is for the export of 114 potential that to the H. H. R. G. Bron S. van Dijl J.M. Biol. PubMed Scopus Google of these are into the by H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google In of proteins are exported the export pathway for (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, the of proteins exported the Tat of of pathway of B. subtilis to on the of signal peptide J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google signal peptides that direct Tat-dependent protein export in as Escherichia or Tat-dependent protein into the of are by the of a is a In this the and the the and were shown to be for Tat-dependent it was that these RR-signal peptides are and signal peptides R. Biol. 1997; PubMed Scopus Google Scholar, S. PubMed Scopus Google Scholar, S. de H. G. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, F. Mol. Microbiol. 2000; Scopus Google Strikingly, the of the was to be could be for a the Tat-dependent export of the protein Biol. 2000; PubMed Scopus Google in the of the two was with a were shown to direct the Tat-dependent of the protein and the protein PubMed Scopus Google Scholar, S. I. Biol. PubMed Scopus Google peptide was recently shown to direct a into the Tat pathway of A. V. PubMed Scopus Google The of these RR-signal peptides that the prediction of signal peptides that direct Tat-dependent protein be on the of is by our of subtilis proteins that are exported of the proteins with in their signal peptide only the phosphodiesterase was exported in a strictly Tat-dependent J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google Tat is that coli. In to the Sec the export of proteins the Tat the of proteins the a Bolhuis A. Rev. Mol. Biol. PubMed Scopus Google The for are the proteins and F. PubMed Scopus Google Scholar, F. Biol. PubMed Scopus Google Scholar, F. Biol. PubMed Scopus Google Scholar, A. Biol. PubMed Scopus Google The has with to be for In to most other contain only subtilis two and The protein was shown to be in the export of the its J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google of the is by a A is not to the the B. subtilis proteins show sequence with the and proteins J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google is not known to the B. subtilis proteins are to the or present were the to the Tat pathway of B. subtilis to the extracellular accumulation of this the extracellular of were by and The show that of 69 proteins with RR- and peptides only protein is secreted in a strictly Tat-dependent 13 other proteins that be by proteomic techniques are secreted In fact, the extracellular accumulation of of these 13 proteins was shown to be The that the export of LipA that LipA is to as in the that LipA is to as in the is and not Tat-dependent was because its conforms to the most stringent criteria for the prediction of RR/KR-signal peptides that direct Tat-dependent RR- and peptides of B. RR- and peptides were in two the of the sequence or is a in of as predicted with the G. PubMed Scopus Google Scholar, I. G. A. 1997; PubMed Google Scholar), was this the of all proteins of B. in the were the of potential signal peptides were with the H. S. G. 1997; PubMed Scopus Google Scholar, H. S. G. PubMed Scopus Google of the sequence or are in In that could as a Sec signal S. 1997; PubMed Scopus Google are in and that the in the signal peptides of LipA and not Sec The is in and the of of these as by the of and Mol. Biol. PubMed Scopus Google Scholar), is these the was is the that the for different are In signal peptides with a predicted signal from to to the signal are of these proteins contain or in the protein with or are a for signal are in H. G. Bron S. van Dijl J.M. The Press, in the of the protein are with in a in and to that be in of the are of a or proteomic In the present studies, proteomic to verify our the of the Tat pathway the of B. subtilis. the the for protein export from the and the extracellular proteome (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google B. subtilis is organism for a proteomic of protein export from the because exported proteins are into the that to the or the many proteins that are with or in the to or H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google Scholar), the of their present show that of 69 proteins with potential RR- or peptides be on the extracellular proteome of B. subtilis in or of are and The proteins were not in the the could be to of of the that and are only of protein or by of these proteins with predicted RR/KR-signal peptides not be exported from the or be in the or these proteins potential proteins and potential the proteins with predicted RR/KR-signal peptides that be in the only PhoD was secreted in a strictly Tat-dependent as J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google In 13 proteins of this were secreted by and the of of these 13 proteins and on the of LipA was to by it was not affected in the with the Tat-dependent extracellular accumulation of the signal peptide of this protein conforms to the most stringent criteria for the prediction of as for known RR-signal peptides of the and and a of S. de H. G. PubMed Scopus Google and A. A. G. S. A. PubMed Scopus Google Strikingly, these stringent criteria to LipA and a extracellular that the present criteria for the prediction of RR/KR-signal peptides to be subtilis. In this it is to in that the predicted RR/KR-signal peptides of the secreted proteins, be by are of these signal peptides has a highly of the or it that signal peptides of B. subtilis to the stringent criteria for RR-signal peptides of in to direct Tat-dependent protein that in the of LipA in the the has on the extracellular appearance of is the could be a direct of the of on LipA as this protein a potential RR-signal peptide and be exported the Tat pathway to the RR-signal peptide of the G. and the other it is that the of LipA in the are to on the of this is a direct of on the export of this is in the The export of LipA is particularly of LipA In fact, as by of the SecA SecA with the export of LipA is of the or of a Tat machinery. by the of SecA the of pre-LipA to of SecA that of is secreted in a strictly A. A. van G. Bron S. van Dijl J.M. Biol. PubMed Scopus Google in is of that the B. subtilis and the with the export of was shown to of SecA R. R. PubMed Google Taken together, our observations show that LipA is the Sec is known to proteins in a it be that the of LipA into its its the be with the that the export of LipA not the Tat pathway, In to the for the prediction of Tat-dependent protein export in B. subtilis, are in the LipA signal peptide are to secrete this protein in a strictly Tat-dependent of of the most extracellular proteins of B. subtilis is by that their is by these proteins, are with signal peptides and and with predicted RR/KR-signal peptides that appear to be by the Tat machinery. The that the in the of the signal peptides of LipA and not as with their extracellular proteins and signal peptides of a known other extracellular proteins, and are as proteins, not SecA for and by signal I. I. 2000; PubMed Scopus Google Scholar, H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google it was shown that proteins be into the in a that the Sec and not SecA B. Biol. PubMed Scopus Google is not of on the of the extracellular proteins was of these proteins are with (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar), two of and peptides that signal peptides. it most that the of these proteins on the Sec machinery. of SecA be for this PhoD of the extracellular proteome of our present observations show in the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis. only this is the be that B. subtilis the Tat pathway for the export of proteins, are and the to to the protein has a RR-signal peptide that a signal In the Sec pathway of B. subtilis, has for protein be for the extracellular accumulation of proteins that are in the of and the that the PhoD protein is present on the extracellular proteome this of for the Tat and Sec of B. subtilis. the other is a and of this protein be the Microbiol. PubMed Scopus Google exported proteins are on the proteome of B. subtilis H. H. PubMed Scopus Google Scholar), it is the of our to to the Tat pathway of B. subtilis is in the of The Gram-positive soil bacterium Bacillus subtilis, is well known for its ability to secrete a large variety of proteins into its extracellular environment. Based on the complete genome sequence (1Kunst F. Ogasawara N. Moszer I. Albertini A.M. Alloni G. Azevedo V. Bertero M.G. Bessieres P. Bolotin A. Borchert S. et al.Nature. 1997; 390: 249-256Crossref PubMed Scopus (3102) Google Scholar), it was recently predicted that the extracellular proteome of this organism is composed of ∼180 different proteins (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, a that extracellular proteins be different proteins were H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google it is not known to of the known protein export to the of the extracellular for protein export are known to be present subtilis. by the of their signal the of secretory proteins has the potential to be exported from the the Sec pathway (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, In this pathway is for the export of 114 potential that to the H. H. R. G. Bron S. van Dijl J.M. Biol. PubMed Scopus Google of these are into the by H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google In of proteins are exported the export pathway for (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar, 3van Dijl J.M. Bolhuis A Tjalsma H. Jongbloed J.D.H. de Jong A. Bron S. Sonenshein A.L. Hoch J.A. Losick R. Bacillus subtilis and its closest relatives. ASM Press, Washington, the of proteins exported the Tat of of pathway of B. subtilis to on the of signal peptide J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google signal peptides that direct Tat-dependent protein export in as Escherichia or Tat-dependent protein into the of are by the of a is a In this the and the the and were shown to be for Tat-dependent it was that these RR-signal peptides are and signal peptides R. Biol. 1997; PubMed Scopus Google Scholar, S. PubMed Scopus Google Scholar, S. de H. G. PubMed Scopus Google Scholar, PubMed Scopus Google Scholar, F. Mol. Microbiol. 2000; Scopus Google Strikingly, the of the was to be could be for a the Tat-dependent export of the protein Biol. 2000; PubMed Scopus Google in the of the two was with a were shown to direct the Tat-dependent of the protein and the protein PubMed Scopus Google Scholar, S. I. Biol. PubMed Scopus Google peptide was recently shown to direct a into the Tat pathway of A. V. PubMed Scopus Google The of these RR-signal peptides that the prediction of signal peptides that direct Tat-dependent protein be on the of is by our of subtilis proteins that are exported of the proteins with in their signal peptide only the phosphodiesterase was exported in a strictly Tat-dependent J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google The Tat is that coli. In to the Sec the export of proteins the Tat the of proteins the a Bolhuis A. Rev. Mol. Biol. PubMed Scopus Google The for are the proteins and F. PubMed Scopus Google Scholar, F. Biol. PubMed Scopus Google Scholar, F. Biol. PubMed Scopus Google Scholar, A. Biol. PubMed Scopus Google The has with to be for In to most other contain only subtilis two and The protein was shown to be in the export of the its J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google of the is by a A is not to the the B. subtilis proteins show sequence with the and proteins J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google is not known to the B. subtilis proteins are to the or The present were the to the Tat pathway of B. subtilis to the extracellular accumulation of this the extracellular of were by and The show that of 69 proteins with RR- and peptides only protein is secreted in a strictly Tat-dependent 13 other proteins that be by proteomic techniques are secreted In fact, the extracellular accumulation of of these 13 proteins was shown to be The that the export of LipA that LipA is to as in the that LipA is to as in the is and not Tat-dependent was because its conforms to the most stringent criteria for the prediction of RR/KR-signal peptides that direct Tat-dependent RR- and peptides were in two the of the sequence or is a in of as predicted with the G. PubMed Scopus Google Scholar, I. G. A. 1997; PubMed Google Scholar), was this the of all proteins of B. in the were the of potential signal peptides were with the H. S. G. 1997; PubMed Scopus Google Scholar, H. S. G. PubMed Scopus Google of the sequence or are in In that could as a Sec signal S. 1997; PubMed Scopus Google are in and that the in the signal peptides of LipA and not Sec The is in and the of of these as by the of and Mol. Biol. PubMed Scopus Google Scholar), is these the was is the that the for different are In signal peptides with a predicted signal from to to the signal are of these proteins contain or in the protein with or are a for signal are in H. G. Bron S. van Dijl J.M. The Press, in the of the protein are with in and to that be in of the are of a or proteomic In the present studies, proteomic to verify our the of the Tat pathway the of B. subtilis. the the for protein export from the and the extracellular proteome (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google B. subtilis is organism for a proteomic of protein export from the because exported proteins are into the that to the or the many proteins that are with or in the to or H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google Scholar), the of their present show that of 69 proteins with potential RR- or peptides be on the extracellular proteome of B. subtilis in or of are and The proteins were not in the the could be to of of the that and are only of protein or by of these proteins with predicted RR/KR-signal peptides not be exported from the or be in the or these proteins potential proteins and potential the proteins with predicted RR/KR-signal peptides that be in the only PhoD was secreted in a strictly Tat-dependent as J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google In 13 proteins of this were secreted by and the of of these 13 proteins and on the of LipA was to by it was not affected in the with the Tat-dependent extracellular accumulation of the signal peptide of this protein conforms to the most stringent criteria for the prediction of as for known RR-signal peptides of the and and a of S. de H. G. PubMed Scopus Google and A. A. G. S. A. PubMed Scopus Google Strikingly, these stringent criteria to LipA and a extracellular that the present criteria for the prediction of RR/KR-signal peptides to be subtilis. In this it is to in that the predicted RR/KR-signal peptides of the secreted proteins, be by are of these signal peptides has a highly of the or it that signal peptides of B. subtilis to the stringent criteria for RR-signal peptides of in to direct Tat-dependent protein that in the of LipA in the the has on the extracellular appearance of is the could be a direct of the of on LipA as this protein a potential RR-signal peptide and be exported the Tat pathway to the RR-signal peptide of the G. and the other it is that the of LipA in the are to on the of this is a direct of on the export of this is in the The export of LipA is particularly of LipA In fact, as by of the SecA SecA with the export of LipA is of the or of a Tat machinery. by the of SecA the of pre-LipA to of SecA that of is secreted in a strictly A. A. van G. Bron S. van Dijl J.M. Biol. PubMed Scopus Google in is of that the B. subtilis and the with the export of was shown to of SecA R. R. PubMed Google Taken together, our observations show that LipA is the Sec is known to proteins in a it be that the of LipA into its its the be with the that the export of LipA not the Tat pathway, In to the for the prediction of Tat-dependent protein export in B. subtilis, are in the LipA signal peptide are to secrete this protein in a strictly Tat-dependent of of the most extracellular proteins of B. subtilis is by that their is by these proteins, are with signal peptides and and with predicted RR/KR-signal peptides that appear to be by the Tat machinery. The that the in the of the signal peptides of LipA and not as with their extracellular proteins and signal peptides of a known other extracellular proteins, and are as proteins, not SecA for and by signal I. I. 2000; PubMed Scopus Google Scholar, H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google it was shown that proteins be into the in a that the Sec and not SecA B. Biol. PubMed Scopus Google is not of on the of the extracellular proteins was of these proteins are with (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar), two of and peptides that signal peptides. it most that the of these proteins on the Sec machinery. of SecA be for this PhoD of the extracellular proteome of our present observations show in the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis. only this is the be that B. subtilis the Tat pathway for the export of proteins, are and the to to the protein has a RR-signal peptide that a signal In the Sec pathway of B. subtilis, has for protein be for the extracellular accumulation of proteins that are in the of and the that the PhoD protein is present on the extracellular proteome this of for the Tat and Sec of B. subtilis. the other is a and of this protein be the Microbiol. PubMed Scopus Google exported proteins are on the proteome of B. subtilis H. H. PubMed Scopus Google Scholar), it is the of our to to the Tat pathway of B. subtilis is in the of in and to that be in of the are of a or proteomic In the present studies, proteomic to verify our the of the Tat pathway the of B. subtilis. the the for protein export from the and the extracellular proteome (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google B. subtilis is organism for a proteomic of protein export from the because exported proteins are into the that to the or the many proteins that are with or in the to or H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google Scholar), the of their present show that of 69 proteins with potential RR- or peptides be on the extracellular proteome of B. subtilis in or of are and The proteins were not in the the could be to of of the that and are only of protein or by of these proteins with predicted RR/KR-signal peptides not be exported from the or be in the or these proteins potential proteins and potential the proteins with predicted RR/KR-signal peptides that be in the only PhoD was secreted in a strictly Tat-dependent as J.D.H. H. Tjalsma H. G. Bron S. van Dijl J.M. Biol. 2000; PubMed Scopus Google In 13 proteins of this were secreted by and the of of these 13 proteins and on the of LipA was to by it was not affected in the with the Tat-dependent extracellular accumulation of the signal peptide of this protein conforms to the most stringent criteria for the prediction of as for known RR-signal peptides of the and and a of S. de H. G. PubMed Scopus Google and A. A. G. S. A. PubMed Scopus Google Strikingly, these stringent criteria to LipA and a extracellular that the present criteria for the prediction of RR/KR-signal peptides to be subtilis. In this it is to in that the predicted RR/KR-signal peptides of the secreted proteins, be by are of these signal peptides has a highly of the or it that signal peptides of B. subtilis to the stringent criteria for RR-signal peptides of in to direct Tat-dependent protein The that in the of LipA in the the has on the extracellular appearance of is the could be a direct of the of on LipA as this protein a potential RR-signal peptide and be exported the Tat pathway to the RR-signal peptide of the G. and the other it is that the of LipA in the are to on the of this is a direct of on the export of this is in the The export of LipA is particularly of LipA In fact, as by of the SecA SecA with the export of LipA is of the or of a Tat machinery. by the of SecA the of pre-LipA to of SecA that of is secreted in a strictly A. A. van G. Bron S. van Dijl J.M. Biol. PubMed Scopus Google in is of that the B. subtilis and the with the export of was shown to of SecA R. R. PubMed Google Taken together, our observations show that LipA is the Sec is known to proteins in a it be that the of LipA into its its the be with the that the export of LipA not the Tat pathway, In to the for the prediction of Tat-dependent protein export in B. subtilis, are in the LipA signal peptide are to secrete this protein in a strictly Tat-dependent manner. The of of the most extracellular proteins of B. subtilis is by that their is by these proteins, are with signal peptides and and with predicted RR/KR-signal peptides that appear to be by the Tat machinery. The that the in the of the signal peptides of LipA and not as with their extracellular proteins and signal peptides of a known other extracellular proteins, and are as proteins, not SecA for and by signal I. I. 2000; PubMed Scopus Google Scholar, H. Tjalsma H. B. S. Bron S. van Dijl J.M. PubMed Scopus Google it was shown that proteins be into the in a that the Sec and not SecA B. Biol. PubMed Scopus Google is not of on the of the extracellular proteins was of these proteins are with (2Tjalsma H. Bolhuis A. Jongbloed J.D.H. Bron S. van Dijl J.M. Microbiol. Mol. Biol. Rev. 2000; 64: 515-547Crossref PubMed Scopus (645) Google Scholar), two of and peptides that signal peptides. it most that the of these proteins on the Sec machinery. of SecA be for this PhoD of the extracellular proteome of our present observations show in the Tat pathway makes a highly selective contribution to the extracellular proteome of B. subtilis. only this is the be that B. subtilis the Tat pathway for the export of proteins, are and the to to the protein has a RR-signal peptide that a signal In the Sec pathway of B. subtilis, has for protein be for the extracellular accumulation of proteins that are in the of and the that the PhoD protein is present on the extracellular proteome this of for the Tat and Sec of B. subtilis. the other is a and of this protein be the Microbiol. PubMed Scopus Google exported proteins are on the proteome of B. subtilis H. H. PubMed Scopus Google Scholar), it is the of our to to the Tat pathway of B. subtilis is in the of F. van for of The for for R. for S. and for and H. G. and of the for