Differential RNA elongation controls the variant surface glycoprotein gene expression sites of Trypanosoma brucei

Mol Microbiol. 2000 Apr;36(2):328-40. doi: 10.1046/j.1365-2958.2000.01844.x.


The protozoan parasite Trypanosoma brucei develops antigenic variation to escape the immune response of its host. To this end, the trypanosome genome contains multiple telomeric expression sites competent for transcription of variant surface glycoprotein genes, but as a rule only a single antigen is expressed at any time. We used reverse transcription-PCR (RT-PCR) to analyse transcription of different segments of the expression sites in different variant clones of two independent strains of T. brucei. The results indicated that RNA polymerase is installed and active at the beginning of many, if not all, expression sites simultaneously, but that a progressive arrest of RNA elongation occurs in all but one site. This defect is linked to inefficient RNA processing and RNA release from the nucleus. Therefore, functional transcription in the active site appears to depend on the selective recruitment of a RNA elongation/processing machinery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Nucleus / metabolism
  • DNA-Directed RNA Polymerases / metabolism*
  • Gene Expression Regulation*
  • Genetic Variation / genetics
  • Polymerase Chain Reaction
  • RNA Processing, Post-Transcriptional
  • RNA, Messenger / metabolism
  • RNA, Protozoan / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Telomere / genetics
  • Transcription, Genetic
  • Trypanosoma brucei brucei / genetics*
  • Trypanosoma brucei brucei / growth & development
  • Variant Surface Glycoproteins, Trypanosoma / genetics*
  • Variant Surface Glycoproteins, Trypanosoma / metabolism


  • RNA, Messenger
  • RNA, Protozoan
  • Variant Surface Glycoproteins, Trypanosoma
  • DNA-Directed RNA Polymerases