Sequence analysis and transcriptional activation of heat shock protein 83 of Leishmania mexicana amazonensis

Abstract

Changes in environmental temperature regulate the differential expression of genes during Leishmania stage differentiation. Therefore, molecular analysis of the heat shock proteins (HSPs) in these parasites is of interest as a model for thermoregulation of gene expression. Sequences of the HSP83 repetitive unit in the genome of Leishmania mexicana amazonensis, including both the coding and intergenic regions, are described. The 5' boundary of the message was mapped by S1 analysis, to potential AG splice sites located 293, 295 and 321 nucleotides upstream of the first ATG. A high degree of conservation (84%) is present between the coding sequence of HSP83 from L. mexicana amazonensis and similar sequences from Trypanosoma cruzi. The intergenic leishmanial sequences, however, were not homologous to similar sequences from HSP83 of trypanosomes, or from HSP70 of Leishmania major. A search for sequences that resemble eukaryote thermoregulated promoters was made and several regions with dyad symmetry were detected. However, only one of these regions was partially homologous with the consensus heat shock element present upstream of all eukaryotic HSPs studied to date.