All ETDs from UAB

Advisory Committee Chair

Terje Dokland

Advisory Committee Members

Todd J Green

Peter E Previlege, Jr

Jamil S Saad

David Schneider

Document Type

Dissertation

Date of Award

2020

Degree Name by School

Doctor of Philosophy (PhD) Heersink School of Medicine

Abstract

Bacteriophage 80α is a temperate double-stranded DNA phage that infects Staphylococcus aureus and is capable of mobilizing a variety of mobile genetic elements named S. aureus Pathogenicity Islands. The capsid of the mature virion is composed of subunits of the capsid protein, portal protein, and a minor capsid protein gp44 as well as packaged phage genomic DNA. The loss of the gp44 protein completely eliminates the phage titer of 80α but does not eliminate the transduction of the pathogenicity islands. In this dissertation, I show that the minor capsid protein is primarily active in a post-ejection role. Without gp44 the phage DNA is reduced to an inactive non-replicative state after infection which can be recovered by the use of a chemical agent, mitomycin C, that triggers the SOS response. Although this may imply a role in establishing the lytic-lysogenic bistable switch, I have shown that gp44 has no interaction with this system and is instead involved in binding to the ends of the phage DNA which does provide protection from exonucleases. This protection may not be a primary role as, stated above, mitomycin C can recover lytic activity post-infection, something not possible if the DNA is degraded. This could imply a role in circularization of the DNA instead.

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