Expression of heat shock protein 83 in Leishmania is regulated post-transcriptionally.
Mechanisms for regulation of heat shock protein (hsp) 83 expression were examined in Leishmania amazonesis. Transcripts of hsp83 accumulated upon temperature elevation; however, in contrast to non-protozoan eukaryotes (i.e. Drosophila, yeast, avian or human cells), no transcriptional activation was observed. The increase in the hsp83 mRNA level evolved from temperature induced variations in mRNA turn-over: the hsp83 transcript was rapidly degraded at normal temperatures, whereas heat shock led to its stabilization. The quick decay of the mRNA at lower temperatures was dependent on active protein synthesis. A similar pattern of regulation was observed for the transfected chloramphenicol acetyltransferase (CAT) gene, which was flanked by sequences from the hsp83 intergenic region (IR), and cloned into the pX transfection vector (pX-ICI). CAT mRNA was abundant at normal temperatures and further accumulated upon temperature elevation. The altered turn-over rates of CAT mRNA at the different temperatures were observed only in the presence of flanking hsp83 IR sequences. The increase in temperature also affected translational regulation of hsps, and synthesis of hsp83 was more efficient at 35 degrees C than at 26 degrees C. However, the effect of translation was transient, and the steady state level of the protein was hardly altered.
Argaman
M
M
Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel.
Aly
R
R
Shapira
M
M
D000818:Animals; D001483:Base Sequence; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D005786:Gene Expression Regulation; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D007894:Leishmania mexicana / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation / Q000187:drug effects; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D016053:RNA, Protozoan / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D013045:Species Specificity; D013696:Temperature; D014158:Transcription, Genetic; D014162:Transfection
D006360:Heat-Shock Proteins; C490310:Hsp83 protein, protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D011993:Recombinant Fusion Proteins; D003609:Dactinomycin; D003513:Cycloheximide