These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Transcriptional regulation of metacyclic variant surface glycoprotein gene expression during the life cycle of Trypanosoma brucei.
    Author: Graham SV, Barry JD.
    Journal: Mol Cell Biol; 1995 Nov; 15(11):5945-56. PubMed ID: 7565747.
    Abstract:
    In antigenic variation in African trypanosomes, switching of the variant surface glycoprotein (VSG) allows evasion of the mammalian host immune response. Trypanosomes first express the VSG in the tsetse fly vector, at the metacyclic stage, in preparation for transfer into the mammal. In this life cycle stage, a small, specific subset (1 to 2%) of VSGs are activated, and we have shown previously that the system of activation and expression of metacyclic VSG (M-VSG) genes is very different from that used for bloodstream VSG genes (S.V. Graham, K.R. Matthews, P.G. Shiels, and J.D. Barry, Parasitology 101:361-367, 1990). Now we show that unlike other trypanosome genes including bloodstream VSG genes, M-VSG genes are expressed from promoters subject to exclusively transcriptional regulation in a life cycle stage-dependent manner. We have located an M-VSG gene promoter, and we demonstrate that it is specifically up-regulated at the metacyclic stage. This is the first demonstration of gene expression being regulated entirely at the level of transcription among the Kinetoplastida; all other protein-coding genes examined in these organisms are, at least partly, under posttranscriptional control. The distinctive mode of expression of M-VSG genes may be due to a stochastic mechanism for metacyclic VSG activation.
    [Abstract] [Full Text] [Related] [New Search]