Binding of trans-acting factors to the double-stranded variant surface glycoprotein (VSG) expression site promoter of Trypanosoma brucei

Vinh Philip Pham, Paul B. Rothman, Keith M. Gottesdiener

Research output: Contribution to journalArticle

Abstract

Trypanosoma brucei evades its host's immune response by utilizing the system of antigenic variation, whereby the organism sequentially expresses antigenically distinct variant surface glycoproteins (VSGs). Actively expressed VSG genes are found in VSG expression sites (ESs), and transcription of these ESs is directed by a small promoter composed of two essential cis-acting elements, the VSG ES promoter upstream element (VUE) and VSG ES promoter downstream element (VDE). Using electrophoretic mobility shift assays, we have identified double-stranded DNA binding activity in bloodstream-form trypanosome nuclear extracts. This activity, the VEP complex, is specific for the VSG ES promoter, and requires the intact sequences of the VUE and VDE in the appropriate spacing. These requirements of VEP Complex formation parallel the requirements for promoter function, suggesting that the VEP complex may be composed of functionally significant trans-acting factors. Furthermore, the requirement of both elements suggests that the binding of factors to the promoter may be cooperative. However, subtly different binding characteristics were observed when we used nuclear extracts derived from procyclic trypanosomes.

Original languageEnglish (US)
Pages (from-to)11-23
Number of pages13
JournalMolecular and Biochemical Parasitology
Volume89
Issue number1
DOIs
StatePublished - Oct 1 1997
Externally publishedYes

Keywords

  • DNA binding
  • Expression site promoter
  • Promoter
  • Trypanosoma brucei
  • Variant surface glycoprotein

ASJC Scopus subject areas

  • Parasitology
  • Molecular Biology

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