The purified yeast pre-mRNA splicing factor PRP2 is an RNA-dependent NTPase.

Abstract

Unlike autocatalyzed self‐splicing reactions, nuclear pre‐mRNA splicing requires transacting macromolecules and ATP. A protein encoded by the PRP2 gene of Saccharomyces cerevisiae is required, in conjunction with ATP, for the first cleavage‐ligation reaction of pre‐mRNA splicing. In this study, we have purified two forms of the PRP2 gene product with apparent molecular weights of 100 kDa and 92 kDa, from a yeast strain overproducing the protein. Both proteins were indistinguishable in their ability to complement extracts derived from a heat‐sensitive prp2 mutant. Furthermore, we show that the PRP2 protein is capable of hydrolyzing nucleoside triphosphates in the presence of single‐stranded RNAs such as poly(U). However, purified PRP2 by itself did not unwind double‐stranded RNA substrates. The fact that an RNA‐dependent NTPase activity is intrinsic to PRP2 may account for the ATP requirement in the first catalytic reaction of pre‐mRNA splicing.