Functional domains of the rDNA promoter display a differential recognition in Leishmania.
A construct containing the RNA polymerase I promoter of Leishmania (L.) amazonensis, driving the expression of cloramphenicol acetyl transferase reporter gene, was better recognised by heterologous hosts species Leishmania (L.) major and Leishmania (L.) mexicana than by the homologous host L. (L.) amazonensis. The rDNA promoter domains responsible for recognition were functionally mapped. The core domain (-74 to +170) conferred a barely equal recognition on homologous or heterologous cells, slightly favouring to the later. Addition of the upstream domain (-196 to -74) repressed the expression in all cells tested. The third domain, consisting of repeated elements (upstream to -196 in L. (L.) amazonensis), enhanced by about 20 times the core activity of homologous species and by about 40 times the heterologous ones. Gel mobility shift patterns generated by the binding of core sequence of L. (L.) amazonensis to nuclear extracts of the Leishmania species suggested that the rDNA transcriptional machinery is a complex DNA-protein association particular for each species. A model is proposed to explain the mechanism and possible interactions of transcription machinery in the regulation of rDNA expression in phylogenically related organisms.
de Andrade Stempliuk
Valeska
V
Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900, São Paulo, SP, Brazil.
Floeter-Winter
Lucile Maria
LM
D000818:Animals; D001483:Base Sequence; D004275:DNA, Ribosomal / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D007891:Leishmania / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012318:RNA Polymerase I / Q000235:genetics* / Q000378:metabolism; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D014157:Transcription Factors; D014158:Transcription, Genetic
D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D014157:Transcription Factors; D012318:RNA Polymerase I