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A heptosyltransferase mutant of Pasteurella multocida produces a truncated lipopolysaccharide structure and is attenuated in virulence

By Marina Harper, Andrew D. Cox, Frank St. Michael, Ian W. Wilkie, John D. Boyce and Ben Adler


Pasteurella multocida is the causative agent of fowl cholera in birds. In a previous study using signature-tagged mutagenesis, we identified a mutant, AL251, which was attenuated for virulence in mice and in the natural chicken host. Sequence analysis indicated that AL251 had an insertional inactivation of the gene waaQPM, encoding a putative heptosyl transferase, required for the addition of heptose to lipopolysaccharide (LPS) (M. Harper, J. D. Boyce, I. W. Wilkie, and B. Adler, Infect. Immun. 71:5440-5446, 2003). In the present study, using mass spectrometry and nuclear magnetic resonance, we have confirmed the identity of the enzyme encoded by waaQPM as a heptosyl transferase III and demonstrated that the predominant LPS glycoforms isolated from this mutant are severely truncated. Complementation experiments demonstrated that providing a functional waaQPM gene in trans can restore both the LPS to its full length and growth in mice to wild-type levels. Furthermore, we have shown that mutant AL251 is unable to cause fowl cholera in chickens and that the attenuation observed is not due to increased serum sensitivity

Topics: Bacterium lipopolysaccharide, Heptose, Heptosyltransferase, Heptosyltransferase III, Transferase, Unclassified drug
Publisher: American Society for Microbiology
Year: 2004
DOI identifier: 10.1128/IAI.72.6.3436-3443.2004
OAI identifier:

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