Tales of Seduction and Betrayal: Host Genes Required for Assault of Salmonella by Bacteriophage P22

The goal of this thesis was to learn if there are host factors encoded by Salmonella typhimurium that phage P22 requires for completion of its life cycle, especially at the step where phage DNA is translocated across the cytoplasmic membrane into the cell. Bacteria with mutations in any of these host factors required by the phage would gain resistance to infection by P22. Consequently, chemically mutagenized bacteria were exposed to a high multiplicity of a virulent P22 derivative and temperature conditional P22$\rm\sp{r}$ mutants were selected. These P22$\rm\sp{r}$ mutants were sorted into four classes according to which step(s) of the P22 life cycle were affected by the host mutation. (1) Reversible adsorption. Lipopolysaccharide mutants were the predominant class and affected reversible adsorption of the phage, these mutants were not characterized further because they have already been well studied. (2) Irreversible adsorption and ejection. A Ts mutation in the infC (translation initiation factor 3) gene affected the irreversible adsorption of P22, preventing the ejection of DNA into the periplasmic space of the recipient bacterium. The mutant also showed pleiotropic defects in outer membrane integrity and growth at 42$\sp\circ$C. (3) DNA uptake. A Ts mutation, tdx, reduced P22-mediated transduction of the recipient by a factor of 1000-fold. This mutant still adsorbed virus particles normally, suggesting that this gene may encode a host factor directly and specifically involved in the translocation of P22 DNA across the cytoplasmic membrane. (4) Phage maturation. Five independent host mutants were recovered which affected the development or morphogenesis of progeny virus particles, even though the mutants still adsorbed P22 and were transduced by P22 transducing particles. Three of these genes (matA, matB, and matD) mapped to the immediate vicinity of another P22-required maturation gene, opdA, at 80 minutes on the genetic map, but were genetically distinct.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Microbiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Lawes, Matthew Charles

Contributors dc:contributor

• Maloy, Stanley R.

• Biology, Molecular

Language dc:language

eng

Identifier

(MiAaPQ)AAI9737174

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/86718