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Doctor of Philosophy (PHD)
Microbiology and Immunology (Medicine)
Date of Defense
First Committee Member
George P. Munson - Committee Member
Second Committee Member
Kenneth A. Fields - Committee Member
Third Committee Member
Lisa R. W. Plano, M.D. - Committee Member
Fourth Committee Member
Terace M. Fletcher - Committee Member
Fifth Committee Member
Timothy L. Yahr - Committee Member
Sixth Committee Member
Gregory Plano - Mentor
YscD is an essential component of the plasmid pCD1-encoded type III secretion system (T3SS) of Yersinia pestis. YscD has a single transmembrane (TM) domain that connects a small N-terminal cytoplasmic region (residues 1 to 121) to a larger periplasmic region (residues 143 to 419). Deletion analyses demonstrated that both the N-terminal cytoplasmic region and the C-terminal periplasmic region are essential for YscD function. Additional studies demonstrated that a predicted cytoplasmic forkhead-associated (FHA) domain of YscD is also required for function; in contrast, a predicted periplasmic phospholipid binding (BON) domain and a putative periplasmic "ring-building" domain of YscD could be deleted with no significant effect on the T3S process. Although deletion of the putative "ring-building" domain did not disrupt T3S activity per se, the calcium-dependent regulation of the T3S apparatus was affected. The extreme C-terminal region of YscD (residues 354 to 419) was essential for secretion activity and had a strong dominant negative effect on the T3S process when exported to the periplasm of the wild type parent strain. Finally, replacement of the YscD TM domain with a TM domain of dissimilar sequence had no effect on the T3S process, indicating that the TM domain has no sequence-specific function in the assembly or function of the T3SS.
Ross, Julia A., "Systematic Deletion and Characterization of the Type III Secretion Apparatus Component YscD of Yersinia pestis" (2010). Open Access Dissertations. 435.