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Characterization of Tankyrase Structure & Function; Evidence for a Role as a Master Scaffolding Protein

De Rycker, Manu
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1102619078

Abstract Details

2005, PhD, University of Cincinnati, Medicine : Molecular Genetics, Biochemistry, and Microbiology.
Tankyrases are novel poly(ADP-ribose) polymerases that have SAM and ankyrin protein-interaction domains. They are found at telomeres, centrosomes, nuclear pores and the Golgi-apparatus, and participate in telomere length regulation and resolution of sister chromatid association. Their other function(s) are unknown and it has been difficult to envision a common role at such diverse cellular locations. We isolated the chicken tankyrase homologs and examined their interaction partners, subcellular location and domain functions to learn more about their mode of action. Cross-species sequence comparison indicated that tankyrase domain structure is highly conserved and supports division of the ankyrin domain into five subdomains, each separated by a highly conserved LLEAAR/K motif. GST-pull down experiments demonstrated that the ankyrin domains of both proteins interact with chicken TRF1. Analysis of total cellular and nuclear proteins showed that cells contain approximately twice as much tankyrase 1 as tankyrase 2. Although ~90% of each protein is cytoplasmic, both tankyrase 1 and 2 were also nuclear. This nuclear location, together with its ability to interact with TRF1, point to a telomeric function for tankyrase 2. This work shows that tankyrases polymerize through their SAM domain to assemble large protein complexes. In vitro polymerization is reversible but still allows interaction with ankyrin-domain binding proteins. Polymerization also occurs in vivo, with SAM-dependent association of overexpressed tankyrase leading to the formation of large tankyrase-containing vesicles, disruption of Golgi structure and inhibition of apical secretion. Finally, tankyrase polymers are dissociated efficiently by poly(ADP-ribosy)lation. This disassembly is prevented by mutation of the PARP domain. Our findings indicate that tankyase 1 promotes both assembly and disassembly of large protein complexes. Thus, tankyrases appear to be master scaffolding proteins that regulate the formation of dynamic protein networks at different cellular locations. This implies a common scaffolding function for tankyrases at each location with specific tankyrase interaction partners conferring location-specific roles to each network, such as telomere compaction or regulation of vesicle trafficking.
Dr. Carolyn Price (Advisor)
138 p.
tankyrase; poly-(ADP-ribosyl)ation; PARP; SAM; sterile alpha motif; polymerization; master scaffolding protein

Recommended Citations

Citations

  • De Rycker, M. (2005). Characterization of Tankyrase Structure & Function; Evidence for a Role as a Master Scaffolding Protein [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1102619078

    APA Style (7th edition)

  • De Rycker, Manu. Characterization of Tankyrase Structure & Function; Evidence for a Role as a Master Scaffolding Protein. 2005. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1102619078.

    MLA Style (8th edition)

  • De Rycker, Manu. "Characterization of Tankyrase Structure & Function; Evidence for a Role as a Master Scaffolding Protein." Doctoral dissertation, University of Cincinnati, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1102619078

    Chicago Manual of Style (17th edition)

ucin1102619078
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© 2004, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.