The twin-arginine protein translocation system (Tat) is a membrane-bound protein complex that transports folded proteins across the thylakoid membranes in plants and cytoplasmic membranes in bacteria. It is predicted that about 50% of the thylakoid lumen proteins use the cpTat pathway. For a precursor to pass the thylakoid membrane under this system, involves the association and dissociation of three proteins, Tha4, Hcf106, and cpTatC, and a proton motive force (PMF). The key mechanistic details as to how the proteins pack together to execute the translocation of the precursor still in question. Previous studies have attempted to investigate the contact points between the components of the Tat system by experimentally determining the crosslinking interactions. These studies have successfully identified crosslinking between the Tat proteins; however, these experiments are tedious. An important prerequisite of functional and structural studies involves the overexpression of the correctly folded membrane proteins. High quality preparations of the overexpressed Tat proteins could lead to successful crystallization and structural determination. The target of this study is to successfully overexpress the fusion of Hcf106 and cpTatC in Escherichia coli, and effectively purify the proteins of interest for future studies that require a “static” structure of the TAT proteins.
Author: Jacob Sapell
Faculty Advisor: Carole Dabney-Smith, Chemistry and Biochemistry
Graduate Student Advisor: Jorge Escobar, Chemistry and Biochemistry
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