Investigation of the Role of the capBCA Locus in Francisella novicida



Risteen, Riley

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Gram negative bacterium Francisella (F.) tularensis is a highly contagious zoonotic pathogen endemic to the United States of America. Though tularemia cases are relatively rare, the potential for F. tularensis to be used as a bioweapon makes studying pathogenesis of this tier 1 biothreat agent important. Previous studies have found the F. tularensis capBCA locus to be important for virulence but did not specify the exact role of this locus. Gram positive bacteria Bacillus anthracis and Bacillus subtillus feature loci with high sequence similarity to the F. tularensis capBCA locus. The B. anthracis capBCA genes encode proteins that are part of a system responsible for producing poly-γ-glutamic acid (PGA) and building a capsule from the polypeptide. The B. subtilis pgsBCA genes similarly encode a system that produces PGA, but the PGA is not attached to the cell surface so the organism does not produce a PGA capsule. Since both the B. anthracis capBCA locus and the B. subtilis pgsBCA locus are responsible for PGA production, we hypothesized that the F. tularensis capBCA locus will perform the same function. We isolated material from a highly related organism, F. novicida, a BSL2 model organism for F. tularensis, but could not confirm that the material contains PGA. These results do not support the theory that the Francisella capBCA locus synthesizes PGA from glutamic acid monomers.



Polyglutamic acid, Francisella tularensis, Francisella novicida, CapBCA locus