Understanding the role of Coxiella outer membrane protein-1 in relation to the Type IVB Secretion system of Coxiella burnetii

Obligate intracellular bacterial pathogens, like Coxiella burnetii, the causative agent of Q Fever, rely upon the host for metabolites and carbon sources for energy and biosynthesis of nucleic acids, proteins, and energy rich molecules necessary for active vegetative growth in the host. Deficiencies in biosynthetic pathways were previously identified through genomic analyses of C. burnetii, but bacterial factors contributing to pathogenesis, with the exception of the O-lipopolysaccharide (O-LPS) and the Type IVb Secretion System (T4BSS), remain elusive. The poor efficacy of treatment and vaccine options necessitates understanding how bacterial factors contribute to disease severity, persistence of infections, and inconsistent treatment outcomes. Disulfide bond (Dsb) proteins are integral in the formation and isomerization of disulfide bonds in the T4bSS. Dsb proteins in other bacterial pathogens act upon known virulence factors that promote pathogenicity. The purpose of this study was to characterize the Coxiella outer membrane protein 1 (Com1), a putative Dsb protein, establish that it is a functional Dsb protein, and that it is linked to known virulence factors. This work will deepen the understanding in the Coxiella field of factors that might serve as alternative targets for therapeutics.Includes bibliographical references

Role of the Small Terminase Subunit Encoded by Staphylococcus Aureus Pathogenicity Island SaPI1 in Formation of SaPI1 Transducing Particles

Staphylococcus aureus pathogenicity island SaPI1 is a genomic element that is mobilized and transduced at high frequency by helper phage 80α. SaPI1 encodes a small terminase protein that belongs to the phage small terminase subunit family. The presence of SaPI1-encoded small terminase suggests that it plays a role in SaPI1-specific packaging into transducing particles by complexing with the 80α large terminase subunit and redirecting recognition to a pac site on SaPI1 DNA from 80α DNA. The effects of deleting the small terminase genes in SaPI1 and in a prophage copy of 80α are consistent with this hypothesis. Induction of the 80α small terminase deletion mutant produces wild type levels of SaPI1 transducing particles, demonstrating that SaPI1 small terminase can replace that of 80a in SaPI1 packaging. Southern blot analysis of virion DNAs isolated from the deletion mutants confirms that SaPI1 redirects packaging of its DNA into SaPI1-sized capsids