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Journal of Bacteriology, January 2000, p. 526-528, Vol. 182, No. 2
Department of Microbiology, University of
Texas Health Science Center, San Antonio, Texas
Received 10 August 1999/Accepted 27 October 1999
The virulence regulatory protein ToxR of Vibrio
cholerae is unique in that it contains a cytoplasmic
DNA-binding-transcriptional activation domain, a transmembrane domain,
and a periplasmic domain. Although ToxR and other transmembrane
transcriptional activators have been discovered in other bacteria,
little is known about their mechanism of activation. Utilizing
degenerate oligonucleotides and PCR, we have amplified internal
toxR gene sequences from seven Vibrio and
Photobacterium species and subspecies, demonstrating that
toxR is an ancestral gene of the family
Vibrionaceae. Sequence alignment of all available ToxR
amino acid sequences revealed a region between the transcriptional
activation and transmembrane domains that displays wide divergence
among Vibrio species. We hypothesize that this region
merely tethers the transcriptional activation domain to the cytoplasmic
membrane and thus can tolerate wide divergence and multiple insertions
and deletions. The divergence in the tether region at the nucleotide
level may provide a useful tool for the distinction of
Vibrio and Photobacterium species.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
A Region of the Transmembrane Regulatory Protein
ToxR That Tethers the Transcriptional Activation Domain to the
Cytoplasmic Membrane Displays Wide Divergence among
Vibrio Species
and
*
Corresponding author. Mailing address: Department of
Microbiology, University of Texas Health Science Center, 7703 Floyd
Curl Dr., San Antonio TX 78284-7758. Phone: (210) 567-3990. Fax: (210) 567-9231. E-mail: klose{at}uthscsa.edu.
Present address: Department of Microbiology, University of Santiago
de Compostela, Campus Sur, 15706 Santiago de Compostela, Spain.
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