The role of genomic location and flanking 3’UTR in the generation of functional levels of Variant Surface Glycoprotein in Trypanosoma brucei
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Trypanosoma brucei faces relentless immune attack in the mammalian bloodstream, where it is protected by an essential coat of Variant Surface Glycoprotein (VSG) comprising ∼10% total protein. The active VSG gene is in a Pol I-transcribed telomeric expression site (ES). We investigated factors mediating these extremely high levels of VSG expression by inserting ectopic VSG117 into VSG221 expressing T. brucei. Mutational analysis of the ectopic VSG 3′UTR demonstrated the essentiality of a conserved 16-mer for mRNA stability. Expressing ectopic VSG117 from different genomic locations showed that functional VSG levels could be produced from a gene 60 kb upstream of its normal telomeric location. High, but very heterogeneous levels of VSG117 were obtained from the Pol I-transcribed rDNA. Blocking VSG synthesis normally triggers a precise precytokinesis cell-cycle checkpoint. VSG117 expression from the rDNA was not adequate for functional complementation, and the stalled cells arrested prior to cytokinesis. However, VSG levels were not consistently low enough to trigger a characteristic ‘VSG synthesis block’ cell-cycle checkpoint, as some cells reinitiated S phase. This demonstrates the essentiality of a Pol I-transcribed ES, as well as conserved VSG 3′UTR 16-mer sequences for the generation of functional levels of VSG expression in bloodstream form T. brucei.
Date Issued
2017-10-11
Date Acceptance
2017-09-12
Citation
Molecular Microbiology, 2017, 106 (4), pp.614-634
ISSN
0950-382X
Publisher
Wiley
Start Page
614
End Page
634
Journal / Book Title
Molecular Microbiology
Volume
106
Issue
4
Copyright Statement
© 2017 The Authors.Molecular MicrobiologyPublished by John Wiley & Sons Ltd.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution andreproduction in any medium, provided the original work is properly cited
License URL
Sponsor
Wellcome Trust
Wellcome Trust
Grant Number
095161/Z/10/Z
099851/Z/12/ZR
Subjects
06 Biological Sciences
11 Medical And Health Sciences
07 Agricultural And Veterinary Sciences
Microbiology
Publication Status
Published