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Journal of Bacteriology, March 1999, p. 1664-1672, Vol. 181, No. 5
Department of Microbiology and Immunology,
Loyola University Medical Center, Maywood, Illinois 60153
Received 2 October 1998/Accepted 22 December 1998
The synthesis and subcellular localization of the proteins that
comprise the Bacillus subtilis spore are under a variety of complex controls. To better understand these controls, we have identified and characterized a 31-kDa sporulation protein, called TasA,
which is secreted into the culture medium early in sporulation and is
also incorporated into the spore. TasA synthesis begins approximately
30 min after the onset of sporulation and requires the sporulation
transcription factor genes spo0H and spo0A. The first 81 nucleotides of tasA encode a 27-amino-acid
sequence that resembles a signal peptide and which is missing from TasA
isolated from a sporulating cell lysate. In B. subtilis
cells unable to synthesize the signal peptidase SipW, TasA is not
secreted, nor is it incorporated into spores. Cells unable to produce
SipW produce a 34-kDa form of TasA, consistent with a failure to remove
the N-terminal 27 amino acids. In cells engineered to express
sipW and tasA during exponential growth, TasA
migrates as a 31-kDa species and is secreted into the culture medium.
These results indicate that SipW plays a crucial role in the export of
TasA out of the cell and its incorporation into spores. Although TasA is dispensable for sporulation under laboratory conditions, we find
that TasA has a broad-spectrum antibacterial activity. We discuss the
possibility that during the beginning of sporulation as well as later,
during germination, TasA inhibits other organisms in the environment,
thus conferring a competitive advantage to the spore.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Secretion, Localization, and Antibacterial Activity
of TasA, a Bacillus subtilis Spore-Associated
Protein
*
Corresponding author. Mailing address: Department of
Microbiology and Immunology, Loyola University Medical Center, 2160 South First Ave., Maywood, IL 60153. Phone: (708) 216-3706. Fax: (708) 216-9574. E-mail: adriks{at}luc.edu.
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