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J. Bacteriol., Jul 1995, 3801-3807, Vol 177, No. 13
D DeShazer, GE Wood and RL Friedman
Transcription of the pertussis toxin operon (ptx) is positively regulated
in Bordetella pertussis by the bvgAS locus. However, a ptx- lacZ
transcriptional fusion in Escherichia coli cannot be activated by bvgAS in
trans. This suggests that an additional factor(s) is required for
transcription of ptx. A gene encoding a Bvg accessory factor (Baf) was
identified by its ability to activate an E. coli ptx-lacZ fusion in the
presence of bvgAS. The expression of ptx-lacZ was decreased by the addition
of 40 mM MgSO4, a compound that also modulates ptx expression in B.
pertussis. Baf alone did not activate expression of an E. coli fhaB-lacZ
fusion, nor did it increase expression of fhaB-lacZ in trans with bvgAS.
The gene encoding Baf was localized, sequenced, and found to produce a
novel 28-kDa protein. Sequences homologous to B. pertussis baf were
identified in Bordetella bronchiseptica and Bordetella parapertussis but
not in Bordetella avium. When an additional copy of baf was integrated into
the chromosome of BC75, a B. pertussis mutant that produces a low level of
pertussis toxin, pertussis toxin production was partially complemented in
the cointegrate strain.
Copyright © 1995, American Society for Microbiology
Identification of a Bordetella pertussis regulatory factor required for transcription of the pertussis toxin operon in Escherichia coli
Department of Microbiology and Immunology, University of Arizona, Tucson 85724, USA.
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