Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2021 Jul 5:9:699639.
doi: 10.3389/fcell.2021.699639. eCollection 2021.

Keeping Balance Between Genetic Stability and Plasticity at the Telomere and Subtelomere of Trypanosoma brucei

Bibo Li  1   2   3   4
Affiliations
Review

Keeping Balance Between Genetic Stability and Plasticity at the Telomere and Subtelomere of Trypanosoma brucei

Bibo Li. Front Cell Dev Biol. .

Abstract

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 host immune response. I will summarize the current understanding about T. brucei telomere protein complex, the telomeric transcript, and telomeric R-loops, focusing on their roles in maintaining telomere and subtelomere stability and integrity. The similarities and differences in functions and underlying mechanisms of T. brucei telomere factors will be compared with those in human and yeast cells.

Keywords: RAP1; TRF; Trypanosoma brucei; genome stability; telomere.

PubMed Disclaimer

Conflict of interest statement

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Trypanosoma brucei has a large VSG gene pool. (A) A representative subtelomeric VSG gene array. (B) A typical minichromosome with a subtelomeric VSG gene. (C) A representative bloodstream form VSG expression site, which is a polycistronic transcription unit and can be expressed while T. brucei proliferates in its mammalian host. (D) A representative metacyclic VSG expression site, which is a monocistronic transcription unit and can be expressed while T. brucei resides in the salivary gland of its insect vector. (E) Major VSG switching pathways. VSGac stands for the originally active VSG. VSGsil stands for an originally silent VSG.
FIGURE 2
FIGURE 2
TRF homologs from various organisms. The DNA binding Myb domain, the homodimerization TRFH domain, the N-terminal acidic domain of human TRF1 and basic GAR domain of human TRF2 are marked whenever identified. In addition, Leishmania amazonensis TRF has been identified and shown to associate with the telomere (da Silva et al., 2010). T. brucei, Trypanosoma brucei; T. vivax, Trypanosoma vivax; T. evansi, Trypanosoma evansi; T. cruzi, Trypanosoma cruzi; L. major, Leishmania major; L. amazonensis, Leishmania amazonensis; A. thaliana, Arabidopsis thaliana; C. griseus, Cricetulus griseus; H. sapiens, Homo sapiens; M. musculus, Mus musculus; O. sativa, Oryza sativa; G. gallus, Gallus gallus; S. pombe, Schizosaccharomyces pombe.
FIGURE 3
FIGURE 3
Repressor activator protein 1 (RAP1) homologous. Tb, Trypanosoma brucei; Hs, Homo sapiens; Sc, Saccharomyces cerevisiae; Sp, Schizosaccharomyces pombe.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Afrin M., Gaurav A. K., Yang X., Pan X., Zhao Y., Li B. (2020a). TbRAP1 has an unusual duplex DNA binding activity required for its telomere localization and VSG silencing. Sci. Adv. 6:eabc4065. 10.1126/sciadv.abc4065 - DOI - PMC - PubMed
    1. Afrin M., Kishmiri H., Sandhu R., Rabbani M. A. G., Li B. (2020b). Trypanosoma brucei RAP1 has essential functional domains that are required for different protein interactions. mSphere 5:e00027-20. 10.1128/mSphere.00027-20 - DOI - PMC - PubMed
    1. Alsford S., Horn D. (2012). Cell-cycle-regulated control of VSG expression site silencing by histones and histone chaperones ASF1A and CAF-1b in Trypanosoma brucei. Nucleic Acids Res. 40 10150–10160. 10.1093/nar/gks813 - DOI - PMC - PubMed
    1. Ambrosini A., Paul S., Hu S., Riethman H. (2007). Human subtelomeric duplicon structure and organization. Genome Biol. 8:R151. 10.1186/gb-2007-8-7-r151 - DOI - PMC - PubMed
    1. Anderson J. A., Song Y. S., Langley C. H. (2008). Molecular population genetics of Drosophila subtelomeric DNA. Genetics 178 477–487. 10.1534/genetics.107.083196 - DOI - PMC - PubMed

LinkOut - more resources

  NODES
INTERN 1
twitter 2