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Journal of Bacteriology, May 1999, p. 2823-2833, Vol. 181, No. 9
Departments of Molecular
Microbiology1 and
Pediatrics,3 Washington University
School of Medicine, St. Louis, Missouri 63110, and Department
of Microbiology, Molecular Biology and Biochemistry, University of
Idaho, Moscow, Idaho 838432
Received 18 November 1998/Accepted 16 February 1999
The ability to move over and colonize surface substrata has been
linked to the formation of biofilms and to the virulence of some
bacterial pathogens. Results from this study show that the
gastrointestinal pathogen Yersinia enterocolitica can
migrate over and colonize surfaces by swarming motility, a form of
cooperative multicellular behavior. Immunoblot analysis and electron
microscopy indicated that swarming motility is dependent on the same
flagellum organelle that is required for swimming motility, which
occurs in fluid environments. Furthermore, motility genes such as
flgEF, flgMN, flhBA, and
fliA, known to be required for the production of flagella,
are essential for swarming motility. To begin to investigate how
environmental signals are processed and integrated by Y. enterocolitica to stimulate the production of flagella and regulate these two forms of cell migration, the motility master regulatory operon, flhDC, was cloned. Mutations within
flhDC completely abolished swimming motility, swarming
motility, and flagellin production. DNA sequence analysis revealed that
this locus is similar to motility master regulatory operons of other
gram-negative bacteria. Genetic complementation and functional analysis
of flhDC indicated that it is required for the production
of flagella. When flhDC was expressed from an inducible
ptac promoter, flagellin production was shown to be
dependent on levels of flhDC expression. Phenotypically,
induction of the ptac-flhDC fusion also corresponded to
increased levels of both swimming and swarming motility.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
The Yersinia enterocolitica Motility
Master Regulatory Operon, flhDC, Is Required for Flagellin
Production, Swimming Motility, and Swarming Motility
*
Corresponding author. Mailing address: Department of
Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110. Phone: (314) 747-2132. Fax: (314) 747-2135. E-mail: virginia{at}borcim.wustl.edu.
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