Translocation alters the activation rate of a trypanosome surface antigen gene
Journal - Nucleic Acids Research
We report here the characterization of the gene coding for AnTat1.13, a very late variable antigen type (VAT) from Trypanosomab.brucei. This gene is chromosome-internal and it is activatedby the duplicative mechanism. Like in another case of late VATexpression (1), its expression-linked copy (ELC) is flankedby "companion" sequences. It was possible to convert the lateexpression of this VAT into an early one, by changing the locationof the gene in the genome. This has been achieved by selectingan AnTat 1.6 clone among heterotypes arising in the AnTat 1.13cloned population. Indeed, this particular derivation leadsto the conservation of the AnTat 1.13 ELC as a new telomericmember of the gene family, and this conserved ELC (or ex-ELC)appears to be preferentially activable. The telomeric positionand other factors possibly involved in early or late antigengene expression are discussed; in this respect, we propose thatsome antigen genes are rarely activated because their duplicativetransposition requires the presence, in the expression site,of "companion" sequences only shared by a limited number ofother genes.