@article{ReynoldsHofmeisterCliffeetal.2016,
  author    = {Reynolds, David and Hofmeister, Brigitte T. and Cliffe, Laura and Alabady, Magdy and Siegel, T. Nicolai and Schmitz, Robert J. and Sabatini, Robert},
  title     = {Histone H3 Variant Regulates RNA Polymerase II Transcription Termination and Dual Strand Transcription of siRNA Loci in Trypanosoma brucei},
  series = {PLoS Genetics},
  volume    = {12},
  journal   = {PLoS Genetics},
  number    = {1},
  doi       = {10.1371/journal.pgen.1005758},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166738},
  pages     = {e1005758},
  year      = {2016},
  abstract  = {Base J, β-D-glucosyl-hydroxymethyluracil, is a chromatin modification of thymine in the nuclear DNA of flagellated protozoa of the order Kinetoplastida. In Trypanosoma brucei, J is enriched, along with histone H3 variant (H3.V), at sites involved in RNA Polymerase (RNAP) II termination and telomeric sites involved in regulating variant surface glycoprotein gene (VSG) transcription by RNAP I. Reduction of J in T. brucei indicated a role of J in the regulation of RNAP II termination, where the loss of J at specific sites within polycistronic gene clusters led to read-through transcription and increased expression of downstream genes. We now demonstrate that the loss of H3.V leads to similar defects in RNAP II termination within gene clusters and increased expression of downstream genes. Gene derepression is intensified upon the subsequent loss of J in the H3.V knockout. mRNA-seq indicates gene derepression includes VSG genes within the silent RNAP I transcribed telomeric gene clusters, suggesting an important role for H3.V in telomeric gene repression and antigenic variation. Furthermore, the loss of H3.V at regions of overlapping transcription at the end of convergent gene clusters leads to increased nascent RNA and siRNA production. Our results suggest base J and H3.V can act independently as well as synergistically to regulate transcription termination and expression of coding and non-coding RNAs in T. brucei, depending on chromatin context (and transcribing polymerase). As such these studies provide the first direct evidence for histone H3.V negatively influencing transcription elongation to promote termination.},
  language  = {en}
}
@article{SiegelVasquezHonetal.2014,
  author    = {Siegel, T. Nicolai and Vasquez, Juan-Jos{\´e} and Hon, Chung-Chau and Vanselow, Jens T. and Schlosser, Andreas},
  title     = {Comparative ribosome profiling reveals extensive translational complexity in different Trypanosoma brucei life cycle stages},
  doi       = {10.1093/nar/gkt1386},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112657},
  year      = {2014},
  abstract  = {While gene expression is a fundamental and tightly controlled cellular process that is regulated at multiple steps, the exact contribution of each step remains unknown in any organism. The absence of transcription initiation regulation for RNA polymerase II in the protozoan parasite Trypanosoma brucei greatly simplifies the task of elucidating the contribution of translation to global gene expression. Therefore, we have sequenced ribosome-protected mRNA fragments in T. brucei, permitting the genome-wide analysis of RNA translation and translational efficiency. We find that the latter varies greatly between life cycle stages of the parasite and ∼100-fold between genes, thus contributing to gene expression to a similar extent as RNA stability. The ability to map ribosome positions at sub-codon resolution revealed extensive translation from upstream open reading frames located within 5' UTRs and enabled the identification of hundreds of previously un-annotated putative coding sequences (CDSs). Evaluation of existing proteomics and genome-wide RNAi data confirmed the translation of previously un-annotated CDSs and suggested an important role for >200 of those CDSs in parasite survival, especially in the form that is infective to mammals. Overall our data show that translational control plays a prevalent and important role in different parasite life cycle stages of T. brucei.},
  subject      = {Ribosom},
  language  = {en}
}