Biochemical Studies of EA22, A Protein Involved in The Bacteriophage Lysogenic-Lytic Decision and the Virulence of Clinically Relevant Serotypes of E. Coli

Enterohemorrhagic Escherichia coli (EHEC) infections are associated with short term gastrointestinal problems, but in some cases, it can lead to more life-threatening conditions. The pathogenicity of EHEC Is supported by an endogenous, dormant bacteriophage that persists in the bacterium as a lysogen until it is activated by a stress-related event. While the lysogenic-lytic development decision has been characterized for decades, there are still genes that are unknown in every way, from structure to function. These genes are found in a region between exo and xis in the l bacteriophage genome which may serve as a model for understanding other related phages in EHEC. This thesis focuses on the protein encoded by the ea22 gene, the largest conserved gene in the exo-xis region. The most significant finding of my research was the expression and characterization of several Ea22 proteins and protein fragments from l and two phages associated with EHEC. Structural differences in the C-terminal domains of these proteins may help explain the broad range of effects the Ea22 proteins mediate during infection.