A trypanosome metacyclic VSG gene promoter with two functionally distinct, life cycle stage-specific activities.
AUTOR(ES)
Graham, S V
RESUMO
In the mammalian bloodstream, African trypanosomes express the variant surface glycoprotein (VSG), continual switching of which allows evasion of the host immune response. Bloodstream VSG genes are transcribed from polycistronic bloodstream expression sites with promoters which are located 45-60 kb upstream. These promoters are not exclusively stage-regulated, being active in the insect midgut stage where VSG is not expressed. However, the metacyclic VSG (M-VSG) genes, a small subset activated when VSG synthesis begins in the metacyclic stage in the tsetse fly salivary glands, are transcriptionally activated specifically in that stage from promoters <3 kb upstream. Using deletion mapping and transient transfection, we show that the entire 1.22 M-VSG gene promoter region (171 bp) is required for full activity in metacyclic-derived trypanosomes. However, a subsidiary, bloodstream stage-specific activity is present in its 5' half which directs transcription initiation very close to the initiation site used in metacyclic-derived trypanosomes. Our results imply that the M-VSG gene promoter is longer and more complex than other VSG gene promoters.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=147490Documentos Relacionados
- Activity of a Trypanosome Metacyclic Variant Surface Glycoprotein Gene Promoter Is Dependent upon Life Cycle Stage and Chromosomal Context
- Global Stage-Specific Gene Regulation during the Developmental Cycle of Chlamydia trachomatis
- The trypanosome spliced leader small RNA gene family: stage-specific modification of one of several similar dispersed genes.
- Sin, a stage-specific repressor of cellular differentiation.
- Involvement of the stage-specific 82-kilodalton adhesion molecule of Trypanosoma cruzi metacyclic trypomastigotes in host cell invasion.