Intraerythrocytic polyubiquitin expression in Plasmodium falciparum is subjected to developmental and heat-hock control

The polyubiquitin gene of the human protozoan parasite Plasmodium falciparu m (PfpUB) was cloned and shown to be comprised of five tandem repeats of th e ubiquitin open reading frame, present as a single copy on chromosome 12, The 1672 bp of PfpUB is interrupted at the 5' end by a single intron of 526 bp. PfpUB expression is developmentally regulated in intraerythrocytic sta ges with a marked increase in both steady-state transcript and polyubiquiti n protein levels in late trophozoite stages. On response to heat shock, lat e stage parasites (late trophozoites and schizonts) have a slightly elevate d PfpUB transcript level as well as readily observable increases in the amo unt:of polyubiquitin and ubiquitin-conjugated proteins. (C) 2000 Elsevier S cience B.V. All rights reserved.