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

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 o...

Full description

Saved in:
Bibliographic Details
Published in:Molecular and biochemical parasitology 1997-10, Vol.89 (1), p.11-23
Main Authors: Pham, Vinh Philip, Rothman, Paul B, Gottesdiener, Keith M
Format: Article
Language:English
Subjects:
Animals
Binding Sites - genetics
Cell Nucleus - chemistry
Cell Nucleus - genetics
DNA binding
DNA, Protozoan - metabolism
DNA, Single-Stranded - metabolism
Expression site promoter
Gene Expression Regulation
Promoter
Promoter Regions, Genetic
Trans-Activators - metabolism
Trypanosoma brucei
Trypanosoma brucei brucei - genetics
Trypanosoma brucei brucei - growth & development
Variant surface glycoprotein
Variant Surface Glycoproteins, Trypanosoma - genetics
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:0166-6851
1872-9428
DOI:10.1016/S0166-6851(97)00094-7