VSG gene 118 is transcribed from a cotransposed pol I-like promoter

• Published in: Cell Vol. 50; no. 4; pp. 603 - 612
• Main Authors: Shea, Cathy, Lee, Mary Gwo-Shu, Van der Ploeg, Lex H.T.
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 14.08.1987; Cell Press
• Subjects: Animals; Antigens, Protozoan - genetics; Biological and medical sciences; Epitopes - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genes; Glycoproteins - genetics; Molecular and cellular biology; Molecular genetics; Nucleic Acid Precursors - metabolism; Promoter Regions, Genetic; RNA - metabolism; RNA Polymerase I - metabolism; RNA Precursors; RNA Splicing; Transcription, Genetic; Transcription. Transcription factor. Splicing. Rna processing; Trypanosoma brucei; Trypanosoma brucei brucei - genetics; Trypanosoma brucei brucei - immunology; Variant Surface Glycoproteins, Trypanosoma; Variant; Protozoa; Regulation(control); Transcription; Transcription promoter; Rhizoflagellata; Glycoproteins; Gene expression; Pathogen; Trypanosoma brucei; Cell surface
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/0092-8674(87)90033-X

To understand the control of differential variant cell surface glycoprotein (VSG) gene expression in T. brucei, we studied VSG gene and expression site transcription regulation. We show that the interchromosomal duplicative transposition of VSG gene 118, on an unusually large transposed segment, results in the transcriptional activation of a cotransposed RNA polymerase I-like (pol I) promoter, from which the VSG gene is transcribed. Transcription of VSG genes by pol I can therefore be regulated by DNA rearrangements that affect positional control of gene expression. A 5′ cap is added in trans to the pol I-derived pre-mRNA, by addition of a pol II-derived 35 nucleotide mini-exon. A second gene (ESAG1) is located 25 kb upstream of the VSG 118 gene and is also transcribed. This expression site therefore contains at least two independently regulated genes. We discuss the putative importance of a nucleolar location for VSG gene and expression site transcription regulation.