RNA polymerase I-mediated protein-coding gene expression in Trypanosoma brucei.

Protein-coding genes are transcribed by RNA polymerise (pol) II in all eukaryotes analyzed to date, with the exception of the protozoan Trypanosoma brucei, where pol I can mediate expression of chloramphenicol acetyl transferase (CAT) and neomycin phosphotransferase (neo) reporter genes. The addition of the capped 39-nucleotide (nt) mini-exon to the pre-messenger RNA (mRNA) by trans-splicing in T. brucei has presumably led to the uncoupling of the requirement for production of mRNA by pol II. Here Hui-min Chung, Mary G-S. Lee and Lex Van der Ploeg review the evidence that supports the notion that pol I also transcribes a subset of naturally occurring protein-coding genes in T. brucei.