Burgess S, Couto J R, Guthrie C
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Cell. 1990 Mar 9;60(5):705-17. doi: 10.1016/0092-8674(90)90086-t.
We previously described a dominant suppressor of the splicing defect conferred by an A----C intron branchpoint mutation in S. cerevisiae. Suppression occurs by increasing the frequency with which the mutant branchpoint is utilized. We have now cloned the genomic region encoding the prp16-1 suppressor function and have demonstrated that PRP16 is essential for viability. A 1071 amino acid open reading frame contains sequence motifs characteristic of an NTP binding fold and further similarities to a superfamily of proteins that includes members with demonstrated RNA-dependent ATPase activity. A single nucleotide change necessary to confer the prp16-1 suppressor phenotype results in a Tyr----Asp substitution near the "A site" consensus for NTP binding proteins. We propose that PRP16 is an excellent candidate for mediating one of the many ATP-requiring steps of spliceosome assembly and that accuracy of branchpoint recognition may be coupled to ATP binding and/or hydrolysis.
