J Biol Chem, Vol. 274, Issue 17, 12103-12107, April 23, 1999
Overproduction and Characterization of the Bacillus
subtilis Anti-sigma Factor FlgM
Michela G.
Bertero
,
Beatriz
Gonzales
,
Cataldo
Tarricone
,
Fabrizio
Ceciliani¶, and
Alessandro
Galizzi
From the
Dipartimento di Genetica e Microbiologia
"A. Buzzati-Traverso," Università degli Studi, Pavia 27100 Italy and the ¶ Dipartimento di Fisiologia Veterinaria e
Biochimica, Università degli Studi, Milano 20133, Italy
FlgM is an anti-sigma factor of the
flagellar-specific sigma (
) subunit of RNA polymerase in
Bacillus subtilis, and it is responsible of the coupling of
late flagellar gene expression to the completion of the hook-basal body
structure. We have overproduced the protein in soluble form and
characterized it. FlgM forms dimers as shown by gel exclusion
chromatography and native polyacrylamide gel electrophoresis and
interacts in vitro with the cognate
D
factor. The FlgM·
D complex is a stable heterodimer as
demonstrated by gel exclusion chromatography, chemical cross-linking,
native polyacrylamide gel electrophoresis, and isoelectric focusing.
D belongs to the group of sigma factors able to bind to
the promoter sequence even in the absence of core RNA polymerase. The
FlgM·
D complex gave a shift in a DNA mobility shift
assay with a probe containing a
D-dependent
promoter sequence. Limited proteolysis studies indicate the presence of
two structural motifs, corresponding to the N- and C-terminal regions, respectively.
Copyright © 1999 by The American Society for Biochemistry and Molecular Biology, Inc.