High constitutive levels of heat-shock proteins in human-pathogenic parasites of the genus Leishmania.
We have analysed the transcription of three heat-shock genes, HSP70, HSP83 and ClpB, in the protozoan parasite Leishmania. All three heat-shock genes are transcribed constitutively and not heat-inducibly. However, we find that two major heat-shock proteins, HSP70 and HSP83, are synthesized at elevated rates during heat stress. We conclude that the cellular stress response in Leishmaniae is regulated exclusively on a post-transcriptional level much in contrast with all other eukaryotes examined so far. The induced synthesis of HSP70 and HSP83, however, does not increase the steady-state level of either protein significantly. This is compensated by high constitutive levels of both proteins: HSP70 and HSP83 make up 2.1% and 2.8%, respectively, of the total protein in unstressed Leishmania promastigotes. Also, HSP70 is a strictly cytoplasmic protein in Leishmania and does not relocate into the nucleus during heat stress, as it does in other eukaryotes examined in the past.
Brandau
S
S
Leishmaniasis Research Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Federal Republic of Germany.
Dresel
A
A
Clos
J
J
D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D017931:DNA Primers; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D007150:Immunohistochemistry; D007893:Leishmania donovani / Q000235:genetics / Q000378:metabolism*; D018320:Leishmania major / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D017931:DNA Primers; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C490310:Hsp83 protein, protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger