The endogenous Bacillus subtilis (natto) plasmids pTA1015 and pTA1040 contain signal peptidase-encoding genes: identification of a new structural module on cryptic plasmids

Mol Microbiol. 1995 Aug;17(4):621-31. doi: 10.1111/j.1365-2958.1995.mmi_17040621.x.


Various strains of Bacillus subtilis (natto) contain small cryptic plasmids that replicate via the rolling-circle mechanism. Like plasmids from other Gram-positive bacteria, these plasmids are composed of several distinct structural modules. A new structural module was identified on the B. subtilis plasmids pTA1015 and pTA1040. It is composed of two genes: one specifies an unidentified protein with a putative signal peptide; and the other (sipP) specifies a functional type 1 signal peptidase (SPase). The homologous, but non-identical, sipP genes of the two plasmids are the first identified plasmid-specific SPase-encoding genes. With respect to structure and activity, the corresponding enzymes (denoted SipP) are highly similar to the chromosomally encoded SPase, SipP, of B. subtillis and several newly identified SPases of other bacilli. Our findings suggest that plasmid-encoded SPases have evolved because, of under certain conditions, SPase can be a limiting factor for protein secretion in B. subtilis.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus subtilis / genetics*
  • Bacterial Proteins / metabolism
  • Base Sequence
  • Blotting, Western
  • Genes, Bacterial*
  • Membrane Proteins*
  • Molecular Sequence Data
  • Mutation
  • Open Reading Frames
  • Plasmids / genetics*
  • Precipitin Tests
  • Protein Sorting Signals / genetics*
  • Sequence Homology, Amino Acid
  • Serine Endopeptidases / genetics*
  • beta-Lactamases / metabolism


  • Bacterial Proteins
  • Membrane Proteins
  • Protein Sorting Signals
  • Serine Endopeptidases
  • type I signal peptidase
  • beta-Lactamases

Associated data

  • GENBANK/L26257
  • GENBANK/L26258
  • GENBANK/L26259
  • GENBANK/X75604
  • GENBANK/Z11847
  • GENBANK/Z33640
  • GENBANK/Z36269