THE PROMOTER FOR THE RIBOSOMAL-RNA GENES OF LEISHMANIA-CHAGASI

A promoter for the rRNA genes of Leishmania chagasi was found to be lo cated about 1 kb upstream of the 18S rRNA coding region and immediatel y downstream of 64 bp tandem repeats. Its approximate boundaries and c orresponding transcription start site were determined by transient tra nsfections and primer extension assays. This promoter for RNA polymera se I has differing activities when transfected into various Leishmania species and no activity in Trypanosoma cruzi. Its sequence has no obv ious similarities with other known rRNA promoters in Trypanosomatids. Depending on the species, this promoter can be used to increase expres sion of a protein from a plasmid in Leishmania by as much as 45-fold o ver that from a plasmid lacking a promoter.