title: Analysis of post-transcriptional regulation operating on transcription products of the tandemly linked Leishmania infantum hsp70 genes.
abstract: The genomic organization and expression of the hsp70 genes of Leishmania infantum were examined. In the cluster there are at least six copies of the hsp70 genes arranged in a head-to-tail tandem of 3. 8-kilobase repetition units. The hsp70 gene copy (gene 6) located at the 3' end of the tandem has a 3'-untranslated region highly divergent in sequence relative to the 3'-untranslated region of the rest of hsp70 gene copies (genes 1-5). Nuclease S1 protection assays indicated that the steady-state level of the mRNAs derived from gene 6 is about 50-fold more abundant than the transcript level derived from genes 1-5. Nuclear run-on assays showed, however, that all hsp70 genes are transcribed at similar rates. Thus, it is likely that the differences in the steady-state levels of the transcripts from the hsp70 genes should be associated with variations in their processing or maturation rates. While the abundance of the mRNAs derived from hsp70 genes 1-5 is increased by heat shock, the hsp70 gene 6 mRNA level remains unaffected. Our data showed that ongoing protein synthesis is required for the maintenance of the heat inducement, depicting, thus, a post-transcriptional mechanism of positive regulation involving a labile protein factor that would be either induced or activated during heat shock.
authors.affiliation: Centro de Biología Molecular "Severo Ochoa," Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Quijada
authors.forename: M
authors.initials: M
authors.lastname: Soto
authors.forename: C
authors.initials: C
authors.lastname: Alonso
authors.forename: J M
authors.initials: JM
authors.lastname: Requena
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation / Q000235:genetics; D017125:Genes, Protozoan; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D018314:Leishmania infantum / Q000235:genetics*; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics; D013696:Temperature; D014158:Transcription, Genetic
chemical_list: D018840:HSP70 Heat-Shock Proteins; D012333:RNA, Messenger