ABSTRACT
A cDNA encoding ribosomal protein L24 was amplified by PCR from the protozoan parasite, Trypanosoma brucei. The 621 nucleotide cDNA had an open reading frame of 375 nucleotides, predicting a highly basic protein of 125 aa. Database searches revealed 33-40% identity between the T. brucei RPL24 protein and several eukaryotic RPL24 homologues. Southern blot analysis indicated that the gene was present as a single copy, and a transcript of approximately 620 nucleotides was detected in procyclic forms of the parasite. Interestingly, T. brucei PRL24 is the smallest eukaryotic RPL24 protein described to date. It is also the most divergent of the known kinetoplastid ribosomal proteins.
Subject(s)
Protozoan Proteins/genetics , Ribosomal Proteins/genetics , Trypanosoma brucei brucei/genetics , Amino Acid Sequence , Animals , Base Sequence , Blotting, Southern , Cloning, Molecular , DNA, Complementary/analysis , Humans , Molecular Sequence Data , Protozoan Proteins/chemistry , Ribosomal Proteins/chemistry , Sequence Alignment , Trypanosoma brucei brucei/cytologyABSTRACT
Poly(A) binding protein I (PABPI) is a highly conserved eukaryotic protein that binds mRNA poly(A) tails and functions in the regulation of translational efficiency and mRNA stability. As a first step in our investigation of the role(s) of mRNA poly(A) tails in posttranscriptional gene regulation in Trypanosoma brucei, we have cloned the cDNA encoding PABPI from this organism. The cDNA predicts a protein homologous to PABPI from other organisms and displaying conserved features of these proteins, including four RNA binding domains that span the N-terminal two-thirds of the protein. Comparison of northern blot data with the cDNA sequence indicates an unusually long 3' untranslated region (UTR) of approximately three kilobases. The 5 UTR contains both A-rich and AU repeat regions, the former being a ubiquitous property of PABPI 5' UTRs. T. brucei PABPI, expressed as a glutathione-S-transferase fusion protein, bound to RNA comprised of its full length 5' UTR in UV cross-linking experiments. This suggests that PABPI may play an autoregulatory role in its own expression. Competition experiments indicate that the A-rich region, but not the AU repeats, are involved in this binding.
