Lancaster EPrints

Ex Vivo and In Vitro Identification of a Consensus Promoter for VSG Genes Expressed by Metacyclic-Stage Trypanosomes in the Tsetse Fly.

Ginger, Michael L. and Blundell, Patricia A. and Lewis, Alyson M. and Browitt, Alison and Günzl, Arthur and Barry, J. David (2002) Ex Vivo and In Vitro Identification of a Consensus Promoter for VSG Genes Expressed by Metacyclic-Stage Trypanosomes in the Tsetse Fly. Eukaryotic Cell, 1 (6). pp. 1000-1009. ISSN 1535-9778

Full text not available from this repository.

Abstract

The trypanosome variant surface glycoprotein (VSG) is first expressed during differentiation to the infective, metacyclic population in tsetse fly salivary glands. Unlike the VSG genes expressed by bloodstream form trypanosomes, metacyclic VSGs (MVSGs) have their own promoters. The scarcity of metacyclic cells has meant that only indirect approaches have been used to study these promoters, and not even their identities have been agreed on. Here, we isolated trypanosomes by dissection from salivary glands and used an approach involving 5' rapid amplification of cDNA ends to identify the transcription start site of three MVSGs. This shows that the authentic start site is that proposed for the MVAT series of MVSGs (K. S. Kim and J. E. Donelson, J. Biol. Chem. 272:24637-24645, 1997). In the more readily accessible procyclic trypanosome stage, where MVSGs are normally silent, we used reporter gene assays and linker scanning analysis to confirm that the 67 bp upstream of the start site is a promoter. This is confirmed further by accurate initiation in a homologous in vitro transcription system. We show also that MVSG promoters become derepressed when tested outwith their endogenous, subtelomeric loci. The MVSG promoters are only loosely conserved with bloodstream VSG promoters, and our detailed analysis of the 1.63 MVSG promoter reveals that its activity depends on the start site itself and sequences 26 to 49 bp and 56 to 60 bp upstream. These are longer than those necessary for the bloodstream promoter.

Item Type: Article
Journal or Publication Title: Eukaryotic Cell
Subjects: Q Science > QH Natural history > QH301 Biology
Departments: Faculty of Health and Medicine > Biomedical & Life Sciences
Faculty of Science and Technology > Mathematics and Statistics
ID Code: 9628
Deposited By: Dr Michael Ginger
Deposited On: 17 Jun 2008 15:07
Refereed?: Yes
Published?: Published
Last Modified: 26 Jul 2012 18:40
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/9628

Actions (login required)

View Item