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Molecular and genetic analysis of a novel f-box protein, seitlupe, in the arabidopsis circadian clock

Han, Linqu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1155569207

Abstract Details

2006, Doctor of Philosophy, Ohio State University, Molecular, Cellular, and Developmental Biology.
The circadian oscillator of Arabidopsis thaliana builds upon interlocked transcriptional feedback loops onto which a diverse array of period-affecting factors are incorporated to culminate into a 24-hour periodicity. A subset of the period-affecting factors function in light input pathways which are specifically connected to the clock, thereby modulating circadian period in a light-dependent manner. A novel F-box protein, ZEITLUPE (ZTL) which controls circadian period in a fluence-rate dependent way, falls into this category. The primary focus of this dissertation is to characterize the light-regulated proteolytic pathway mediated by ZTL. At first we identified the SCFZTL complex in planta and established that the formation of SCFZTL complex is important for proper regulation of circadian clock. SCFZTL complex targets an essential oscillator component, TOC1 for its proteasome-dependent degradation. TOC1/PRR1 is the founding member of a small gene family of Pseudoresponse Regulators (PRRs) which consists of additional four genes (PRR3,PRR5,PRR7 and PRR9). The transcriptional regulations among PRR members partially define the interlocked transcriptional feedback loops which are at the core of central oscillator. In this study we characterized the expression pattern of all PRR members and identified two post-translational regulatory events which are shared by four PRR members (PRR1/3/5/7): phosphorylation and proteasome-dependent protein turn over. In addition, we identified PRR5 as a novel interactor of ZTL. In order to further characterize biochemical properties of ZTL and more broadly, to better understand the ZTL-mediated light signal transduction pathway which is specifically coupled to circadian clock, we took both forward and reverse genetic approaches. First, we dissected the roles of three distinctive domains of ZTL in the regulation of circadian period and photomorphogenesis. We found that the C-terminal F/KELCH domain could act together to alter circadian period, when overexpressed, similar to the effect of overexpression of full length ZTL protein. Second, we conducted a suppressor screen for intragenic and extragenic mutations which antagonize the gain-of-function effects mediated by high constitutive expression of ZTL. The suppressor screen identified key residues in ZTL function and suggested new loci in circadian clock function.
David Somers (Advisor)
Greg Armstrong (Other)
David Bisaro (Other)
David Mackey (Other)
179 p.
Biology, Plant Physiology
Circadian clock; ZEITLUPE; F-box protein

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Citations

  • Han, L. (2006). Molecular and genetic analysis of a novel f-box protein, seitlupe, in the arabidopsis circadian clock [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155569207

    APA Style (7th edition)

  • Han, Linqu. Molecular and genetic analysis of a novel f-box protein, seitlupe, in the arabidopsis circadian clock. 2006. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1155569207.

    MLA Style (8th edition)

  • Han, Linqu. "Molecular and genetic analysis of a novel f-box protein, seitlupe, in the arabidopsis circadian clock." Doctoral dissertation, Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1155569207

    Chicago Manual of Style (17th edition)

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© 2006, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.