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INVESTIGATION OF THE POTENTIAL INTERACTIVE COMPONENTS OF cpTAT PATHWAY WITH THE PRECURSOR DURING TRANSPORT

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2014, Doctor of Philosophy, Miami University, Chemistry and Biochemistry.
Proteins destined for the thylakoid lumen of chloroplasts must cross three membranes en route. The chloroplast Twin Arginine Translocation (cpTat) system facilitates transport of about half of all proteins that cross the thylakoid membrane in chloroplasts. It transports fully folded proteins only in the presence of proton motive force generated during photosynthesis. However, key details such as the structure and composition of the translocation pore are still unknown. One of the three transmembrane cpTat components, Tha4, is thought to function as the pore by forming an oligomer. Little work has been done to detect precursor-Tha4 interactions, which are expected if Tha4 is the pore. My doctoral research investigated the potential interactive channel-forming component of cpTat system during transport. We found evidence for interaction of the mature domain of the precursor with Tha4 under conditions leading to transport, using cysteine substitutions on the precursor and Tha4 and disulfide bond formation in pea (Pisum sativum). The mature domain of a transport-competent precursor interacts with the amphipathic helix and amino terminus of functional Tha4 under conditions leading to transport. However, considering the large size of the precursor, the biggest question still remains whether the translocation channel is exclusively made up of Tha4 or other cpTat components, which might also participate to provide membrane passage to the mature domain of the precursor. The receptor complex component Hcf106 is structurally homologous to Tha4 and it can also form a higher order oligomer at the translocase. Little is known about the function of Hcf106 in cpTat pathway. Here we present data that demonstrates a direct interaction between precursor mature domain with the cpTat receptor complex component, Hcf106 by using a disulfide exchange crosslinking strategy. Chapter 4 discusses initial method developments and molecular biology techniques used to determine whether the conservative protein sorting "Tat" system is present in the plant mitochondrial membrane. The mitochondria tatC gene in Nicotiana tabacum was upregulated under stress conditions. Although no other evidence has confirmed the presence of two other Tat pathway components Hcf106 (TatB in bacteria) and Tha4 (TatA in bacteria) in plant mitochondria, it is unlikely that the entire Tat pathway would be carried out solely by mtTatC. We investigated whether Tha4 dual targeted to both chloroplast and mitochondria under stress using Nicotiana tabacum as a model system for our study.
Carole Dabney-Smith (Advisor)
Christopher Makaroff (Committee Chair)
Gary Lorigan (Committee Member)
Hong Wang (Committee Member)
Richard Moore (Committee Member)
140 p.

Recommended Citations

Citations

  • Pal, D. (2014). INVESTIGATION OF THE POTENTIAL INTERACTIVE COMPONENTS OF cpTAT PATHWAY WITH THE PRECURSOR DURING TRANSPORT [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1401969405

    APA Style (7th edition)

  • Pal, Debjani. INVESTIGATION OF THE POTENTIAL INTERACTIVE COMPONENTS OF cpTAT PATHWAY WITH THE PRECURSOR DURING TRANSPORT. 2014. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1401969405.

    MLA Style (8th edition)

  • Pal, Debjani. "INVESTIGATION OF THE POTENTIAL INTERACTIVE COMPONENTS OF cpTAT PATHWAY WITH THE PRECURSOR DURING TRANSPORT." Doctoral dissertation, Miami University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=miami1401969405

    Chicago Manual of Style (17th edition)