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Media type:
E-Article
Title:
Sporulation-Specific σ Factor σ29of Bacillus subtilis is Synthesized from a Precursor Protein, P31
Contributor:
LaBell, Terry L.;
Trempy, Janine E.;
Haldenwang, William G.
Published:
National Academy of Sciences of the United States of America, 1987
Published in:
Proceedings of the National Academy of Sciences of the United States of America, 84 (1987) 7, Seite 1784-1788
Language:
English
ISSN:
0027-8424
Origination:
Footnote:
Description:
Evidence is presented that a sporulation-essential σ factor of Bacillus subtilis, σ29, is synthesized as an inactive precursor (P31) and that its activation occurs by a developmentally regulated cleavage of 29 amino acids from the P31amino terminus. A pulse--chase experiment demonstrated that σ29was derived from a preexisting protein, with appearance of radioactively labeled σ29paralleling the disappearance of labeled P31. The disappearance of pulse-labeled P31did not occur when the experiment was done with a B. subtilis strain carrying a mutation in a locus (spoIIE) required for σ29, but not P31, synthesis. Microsequencing of σ29protein revealed that its amino terminus originates at amino acid 30 of the P31amino acid sequence. In order to test whether a proteolytic event alone could activate P31to a protein with σ29-like properties, a fusion protein (P31* ) containing most of P31was overproduced in Escherichia coli and converted in vitro into a protein with the electrophoretic mobility of σ29by limited treatment with Staphylococcus aureus V8 protease. Protease-treated P31* , but not untreated P31* , was capable of directing B. subtilis core RNA polymerase to specifically initiate RNA synthesis at a σ29-recognized promoter in vitro.