Transcription of telomere repeats in protozoa.
The telomerically located variant cell surface glycoprotein (VSG) gene expression sites of the protozoan parasite Trypanosoma brucei are transcribed by an unusual alpha-amanitin resistant RNA polymerase. We show that the telomere GGGTTA repeats located at the chromosome ends of T. brucei and the related protozoan T. equiperdum are also transcribed by alpha-amanitin resistant RNA polymerases. This transcription predominantly proceeds unidirectionally towards the end of the chromosome, in both bloodstream and insect form trypanosomes and results in the generation of heterogeneously sized steady state RNA. We postulate that telomere repeat transcription results from readthrough downstream of telomeric genes. Telomere repeat transcription was found in all seven protozoan species tested, but was alpha-amanitin resistant only in trypanosome species which exhibited antigenic variation. The data indicate that in some trypanosome species a subset of telomeres is transcribed by a different type of RNA polymerase.
Rudenko
G
G
Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, NY, NY 10032.
Van der Ploeg
L H
LH
D000546:Amanitins / Q000494:pharmacology; D000818:Animals; D002875:Chromosomes / Q000032:analysis; D056890:Eukaryota / Q000235:genetics*; D010957:Plasmids; D010963:Plasmodium falciparum / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000235:genetics*; D014351:Trypanosomatina / Q000235:genetics; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000235:genetics*
D000546:Amanitins; D014643:Variant Surface Glycoproteins, Trypanosoma