Unique features of the Trypanosoma Cruzi U2AF35 splicing factor

VAZQUEZ, MARTIN; ATORRASAGASTI, CATALINA; BERCOVICH, NATALIA; VOLCOVICH, ROMINA; LEVIN, MARIANO J

MOLECULAR AND BIOCHEMICAL PARASITOLOGY

ELSEVIER SCIENCE BV

Año: 2003 vol. 128 p. 77 - 81

0166-6851

The pre-mRNA splicing reaction requires the formation of a series of highly dynamic spliceosomal complexes. These complexes are composed of U1, U2, U4, U5 and U6 small nuclear RNAs (snRNAs) and around 50 proteins [1,2]. The E, A and B complexes contain unspliced pre-mRNA and the C complex contains the products of the first catalytic step of the splicing reaction [2]. In trypanosomatids, few pre-mRNA sequences are required for trans-splicing, including a conserved AG dinucleotide at the 3acceptor site (3SS) preceded by a polypyrimidine tract (pPY) of variable length (8–40 bases) at a variable distance (1–35 bases) from the 3SS [3], and an adenosine, usually the first one upstream of the pPY tract, that serves as nucleophile in the reaction [4]. Although snRNAs and associated proteins (snRNP) have been identified, mainly in Trypanosoma brucei [5], no information is available as to the tryponasome proteins involved in the initial ATP-independent stage of spliceosomal assembly (E complex).