Characterization of ribosomal RNA processing by spliced leader addition trans-splicing in trypanosomatids and its possible biological meaning

• Grant number: 08/57462-8
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2009
• End date: July 31, 2011
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Lucile Maria Floeter-Winter
• Grantee: Lucile Maria Floeter-Winter
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The addition of a capped mini-exon by trans-splicing is an essential step in the maturation of RNA polymerase II transcribed polycistronic pre-mRNAs in trypanosomatids. The process is coupled to polyadenylation of the previous messenger in the precursor RNA molecule. Previous observation of expression of reporter proteins, which transcription was driven by RNA polymerase I (RNA pol I) lead to the hypothesis of the existence of trans-splicing signaling in the external transcribed spacer (ETS) of ribosomal RNA precursor (rRNA). This observation may be an indicative that this RNA processing is not restricted to pre-mRNA but also occurs using RNA pol I transcribed pre-small subunit ribosomal RNAs (SSU rRNA) as acceptor substrates. The main goal of the present project is to show the occurrence of mini-exon addition to the transcribed pre-rRNA, as well as to point out a possible functional role of such RNA processing step, that is up to the present exclusive to mRNA production. The determination of a conservative mechanism also may indicate the existence of an evolutionary pressure; reinforce a natural function that leads to its preservation, or an indicative of an ancient gene expression strategy used by organisms with partial specialized RNA polymerases. (AU)