A transcript encoding a proteasome beta-subunit and a zinc finger protein in Trypanosoma brucei brucei

During the screening of a Trypanosoma brucei brucei (T. b. brucei) cDNA lib rary constructed from bloodstream form mRNA, we identified a 2.3 kb cDNA en coding a proteasome beta subunit (ORF1) and a putative zinc finger protein (ORF2). Northern blot analysis indicated the presence of a digenic transcri pt as well as the two individual messengers in both procyclic and bloodstre am forms of the parasite. Southern blot analysis showed the relevant locus to be unique. QRF1 encoded a 22.7 kDa protein sharing over 50% identity wit h the eukaryotic PRCE (aka beta5) proteasome beta subunit. This protein con tained a beta amino acid signature and residues involved in the catalytic a ctivity. Further phylogenetic analysis indicated that this subunit as well as those from other kinetoplastids could be confidentially assigned to exta nt eukaryotic subfamilies such as beta1, beta2, and beta5. ORF2 encoded a 1 4.6 kDa putative zinc finger protein containing five repeats of a CCHC moti f commonly present in retroviral nucleocapsid proteins as well as proteins involved in vertebrate embryogenesis. (C) 2000 Elsevier Science B.V. All ri ghts reserved.