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Full-Text Articles in Biology

Telomere Maintenance In African Trypanosomes, Bibo Li Ph.D. Nov 2023

Telomere Maintenance In African Trypanosomes, Bibo Li Ph.D.

Biological, Geological, and Environmental Faculty Publications

Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve …


Keeping Balance Between Genetic Stability And Plasticity At The Telomere And Subtelomere Of Trypanosoma Brucei, Bibo Li Ph.D. Jul 2021

Keeping Balance Between Genetic Stability And Plasticity At The Telomere And Subtelomere Of Trypanosoma Brucei, Bibo Li Ph.D.

Biological, Geological, and Environmental Faculty Publications

Telomeres, the nucleoprotein complexes at chromosome ends, are well-known for their essential roles in genome integrity and chromosome stability. Yet, telomeres and subtelomeres are frequently less stable than chromosome internal regions. Many subtelomeric genes are important for responding to environmental cues, and subtelomeric instability can facilitate organismal adaptation to extracellular changes, which is a common theme in a number of microbial pathogens. In this review, I will focus on the delicate and important balance between stability and plasticity at telomeres and subtelomeres of a kinetoplastid parasite, Trypanosoma brucei, which causes human African trypanosomiasis and undergoes antigenic variation to evade the …


Trypanosoma Brucei Rap1 Has Essential Functional Domains That Are Required For Different Protein Interactions, Marjia Afrin, Hanadi Kishmiri, Ranjodh Sandhu, M. A.G. Rabbani, Bibo Li Jan 2020

Trypanosoma Brucei Rap1 Has Essential Functional Domains That Are Required For Different Protein Interactions, Marjia Afrin, Hanadi Kishmiri, Ranjodh Sandhu, M. A.G. Rabbani, Bibo Li

Biological, Geological, and Environmental Faculty Publications

RAP1 is a telomere protein that is well conserved from protozoa to mammals. It plays important roles in chromosome end protection, telomere length control, and gene expression/silencing at both telomeric and nontelomeric loci. Interaction with different partners is an important mechanism by which RAP1 executes its different functions in yeast. The RAP1 ortholog in Trypanosoma brucei is essential for variant surface glycoprotein (VSG) monoallelic expression, an important aspect of antigenic variation, where T. brucei regularly switches its major surface antigen, VSG, to evade the host immune response. Like other RAP1 orthologs, T. brucei RAP1 (TbRAP1) has conserved functional domains, including …


Trypanosoma Brucei Telomere Functions In Antigenic Variation, Unnati M. Pandya Jan 2014

Trypanosoma Brucei Telomere Functions In Antigenic Variation, Unnati M. Pandya

ETD Archive

Trypanosoma brucei is a protozoan parasite that causes sleeping sickness in humans and Nagana in cattle. They evade the host's immune defense by periodically switching their major surface antigen, variant surface glycoprotein (VSG), a phenomenon termed antigenic variation. Inside its mammalian host, bloodstream form (BF) T. brucei monoallelically expresses its major surface molecule VSG from the VSG Expression Sites (ESs) located at subtelomeric loci. Monoallelic VSG expression ensures effective antigenic variation and maximizes the efficiency of T. brucei pathogenesis. In the mid-gut of its insect host (tsetse), procyclic form (PF) T. brucei expresses procyclins as the major surface molecules and …