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FUNCTIONAL INTERACTION ANALYSIS OF CHLOROPLAST TWIN ARGININE TRANSLOCATION (CPTAT) PATHWAY AND ITS ROLE IN PLASTID DEVELOPMENT

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2016, Doctor of Philosophy, Miami University, Cell, Molecular and Structural Biology (CMSB).
The Twin arginine translocation (Tat) system is an ancient and evolutionarily conserved system which translocates fully-folded proteins across thylakoidal membrane in chloroplasts as well as cytoplasmic membrane of eubacteria and archaebacteria. In chloroplasts, the cpTat system carries out the function in translocating roughly half of the critical photosynthetic lumenal proteins. During the past two decades, the core components of this protein translocase has been identified, and the representative structures of the components from bacterial homologues have been obtained. What still remains largely unknown is the molecular mechanism of the cpTat pathway. Understanding how cpTat components interact will provide important clues towards solving the transport mechanism of cpTat. Two core components, Hcf106 and cpTatC, play a major role in binding the substrate signal peptide and recruiting of the pore-forming component Tha4. This dissertation mainly describes the development of a technique using thylakoid-integrated recombinant Hcf106 to study its contribution to the cpTat pathway and usage of the recombinant Hcf106 as a probe to investigate the interaction between Hcf106 and other cpTat components. We detected close contacts between Hcf106 and cpTatC and mapped the architecture of the Hcf106-cpTatC complex. In addition, we trapped a Hcf106-cpTatC-Tha4 trimer via their transmembrane helices for the first time. All these data support a model that Hcf106 plays a role in controlling Tha4 entering the cavity of cpTatC, which initiates precursor translocation. Most of the knowledge concerning the mechanism of cpTat pathway in chloroplasts has been obtained through experiments with isolated pea chloroplasts, and it is assumed that all higher plants utilize the same general transport apparatus. To further understand the role of cpTat in plastid development, we characterized a HCF106 mutant of cpTat pathway, pgw, in the model plant Arabidopsis thaliana to investigate how cpTat system deficiency affects the thylakoids biogenesis and plant development. We detected underdeveloped thylakoids and defects in cpTat transport in pgw, and a possible retrograde signaling pathway was associated with the cpTat deficiency. We conclude that as one of the core component of cpTat pathway, HCF106 plays an important role in Arabidopsis thylakoid development.
Carole Dabney-Smith (Advisor)
Michael Crowder (Committee Chair)
Rick Page (Committee Member)
Heeyoung Tai (Committee Member)
Rachael Morgan-Kiss (Committee Member)
105 p.

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Citations

  • Ma, Q. (2016). FUNCTIONAL INTERACTION ANALYSIS OF CHLOROPLAST TWIN ARGININE TRANSLOCATION (CPTAT) PATHWAY AND ITS ROLE IN PLASTID DEVELOPMENT [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1477671264917956

    APA Style (7th edition)

  • Ma, Qianqian. FUNCTIONAL INTERACTION ANALYSIS OF CHLOROPLAST TWIN ARGININE TRANSLOCATION (CPTAT) PATHWAY AND ITS ROLE IN PLASTID DEVELOPMENT . 2016. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1477671264917956.

    MLA Style (8th edition)

  • Ma, Qianqian. "FUNCTIONAL INTERACTION ANALYSIS OF CHLOROPLAST TWIN ARGININE TRANSLOCATION (CPTAT) PATHWAY AND ITS ROLE IN PLASTID DEVELOPMENT ." Doctoral dissertation, Miami University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1477671264917956

    Chicago Manual of Style (17th edition)