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Faculty Advisors

Li, Bibo


The protozoan parasite Trypanosoma brucei causes fatal African trypanosomiasis in humans and nagana in cattle. T. brucei switches its variant surface glycoproteins (VSGs) inside the mammalian host, evading the host immune response. VSGs are expressed monoallelically from subtelomeric expression sites, and telomere proteins regulate VSGs. We previously found that telomere protein TbTIF2 interacts with TbTRF (TTAGGG-repeat binding factor) and plays important roles in VSG switching regulation. TbTRF maintains the telomere terminal structure. TbTIF2 is essential for subtelomeric integrity and suppresses VSG switching by inhibiting subtelomeric gene conversion. Depletion of TbTIF2 decreases TbTRF protein level. We hypothesize that TbTRF-TbTIF2 interaction is essential for maintaining TbTRF protein level. We test this hypothesis by mapping the interaction between TbTRF andTbTIF2. TbTRF has both N-terminal TRF Homology (TRFH) and C-terminal Myb domains. TbTRFH contains seven helices and interacts with the N-terminus of TbTIF2 (aa 2-190). We found that deleting either of the first two helices in TbTRFH abolishes its interaction with TbTIF2. Currently we are generating deletion and point mutations within the first two helices of TbTRFH, which will be tested for their ability to interact with TbTIF2 to determine the key residues in TbTRFH that are required for interacting with TbTIF2.

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College of Sciences and Health Professions

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Characterization of the detailed interaction interface between T. brucei telomere proteins TRF and TIF2