Regulation of antigenic variation by a DOT1B/RNaseH2 complex in Trypanosoma brucei
Final Report Abstract
Antigenic variation is one of the most sophisticated strategies used by pathogens, such as Trypanosoma Trypanosoma, Borrelia or Neisseria, to escape the immune system of their hosts. Trypanosomes periodically changes the expression of protective variant surface glycoproteins (VSGs) to evade the immune system of their mammalian hosts. One route to change VSG expression is the transcriptional activation of a previously silent VSG expression site (ES), a subtelomeric region containing the VSG genes. Homologous recombination of a different VSG from a large reservoir into the active ES represents another route. Many molecular details of these processes are still elusive. We could demonstrate that the conserved histone methyltransferase DOT1B is involved in transcriptional silencing of active ES and influences ES switching kinetics. The molecular machinery that enables DOT1B to execute these regulatory functions remains elusive, however. To better understand DOT1B- mediated regulatory processes, we purified DOT1B-associated proteins using complementary biochemical approaches. We identified several novel DOT1B-interactors. One of these was the Ribonuclease H2 complex, previously shown to resolve RNA-DNA hybrids, maintain genome integrity, and play a role in antigenic variation. Our study revealed that DOT1B depletion results in an increase in RNA-DNA hybrids, accumulation of DNA damage and recombination-based ES switching events. Surprisingly, a similar pattern of VSG deregulation was observed in Ribonuclease H2 mutants. We propose that both proteins act together in resolving R-loops to ensure genome integrity and contribute to the tightly regulated process of antigenic variation.
Publications
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Novel and conserved roles of the histone methyltransferase DOT1B in trypanosomatid parasites. Dissertation, University of Würzburg, Graduate School of Life Science
Eisenhuth N.
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A DOT1B/Ribonuclease H2 Protein Complex Is Involved in R-Loop Processing, Genomic Integrity, and Antigenic Variation in Trypanosoma brucei. mBio, 12(6).
Eisenhuth, Nicole; Vellmer, Tim; Rauh, Elisa T.; Butter, Falk & Janzen, Christian J.
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DOT1B is dispensable for stage differentiation in Leishmania mexicana but not for efficient infection of macrophages. VIII Kinetoplastid Molecular Cell Biology meeting, September 13-17, Woods Hole MA, USA
Rauh E.T., Eisenhuth N., Butter F., Debus A., Schleicher U. & Janzen C.J.
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The histone methyltransferase DOT1B is dispensable for stage differentiation and macrophage infection of Leishmania mexicana. Frontiers in Cellular and Infection Microbiology, 14.
Eisenhuth, Nicole; Rauh, Elisa Theres; Mitnacht, Melina; Debus, Andrea; Schleicher, Ulrike; Butter, Falk; Pruzinova, Katerina; Volf, Petr & Janzen, Christian J.
