An unusual liaison: Small nuclear and cytoplasmis RNA genes team up with tRNA genes in trypanosomatid protozoa

Abstract The study of transcription has revealed a complex and diverse set of biochemical interactions between sequence-specific DNA-binding proteins, promoter and enhancer elements, and the basal transcriptional apparatus consisting of RNA polymerase and a variety of accessory factors. Our understanding of promoter structures and trans-acting factors in trypanosomatid protozoa is at present quite limited, but is clearly gaining momentum. Only recently, through the advent of DNA transfection technology, has it become possible to identify the cis-acting DNA sequences involved in gene expression in these organisms. Here, Valerian Nakaar, Christian Tschudi and Elisabetta Ullu summarize some recent insights into the structure and functioning of RNA polymerase III transcription units coding for small nuclear and cytoplasmic RNAs in trypanosomatid protozoa.