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J Bacteriol 2008 Jul;190(13):4584-95

The Francisella Pathogenicity Island Protein PdpD is required for full virulence and associates with homologues of the type VI secretion system.

Ludu JS, de Bruin OM, Duplantis BN, Schmerk CL, Chou AY, Elkins KL, Nano FE

Nano, FE (reprint author), Univ Victoria, Dept Biochem & Microbiol, POB 3055 STN CSC, Victoria, BC V8W 3P6 Canada Univ Victoria, Dept Biochem & Microbiol, Victoria, BC V8W 3P6 Canada US FDA, Ctr Biol Evaluat & Res, Bethesda, MD USA


Francisella tularensis is a highly infectious, facultative intracellular bacterial pathogen that is the causative agent of tularemia. Nearly a century ago researchers observed that tularemia was often fatal in North America, but almost never fatal in Europe and Asia. The chromosomes of F. tularensis strains carry two identical copies of the Francisella pathogenicity island (FPI), and the FPI of North American-specific biotypes contain two genes, anmK and pdpD, that are not found in biotypes that are distributed over the entire Northern Hemisphere. In this work we have studied the virulence contribution of anmK and pdpD using F. novicida, which is very closely related to F. tularensis but which carries only one copy of the FPI. We showed that anmK and pdpD are necessary for full virulence but not for intracellular growth. This is in sharp contrast to most other FPI genes that have been studied to date, which are required for intracellular growth. We also showed that PdpD is localized to the outer membrane. Further, over-expression of PdpD affects the cellular distribution of FPI-encoded proteins IglA, IglB and IglC. Finally, deletions of FPI genes encoding proteins that are homologues of known components of type VI secretion systems abolished the altered distribution of IglC and the outer membrane localization of PdpD.

Category: Journal Article
PubMed ID: #18469101
Includes FDA Authors from Scientific Area(s): Biologics
Entry Created: 2011-10-04 Entry Last Modified: 2012-08-29