U14 FUNCTION IN SACCHAROMYCES-CEREVISIAE CAN BE PROVIDED BY LARGE DELETION VARIANTS OF YEAST U14 AND HYBRID MOUSE YEAST U14 RNAS

The functional equivalency of yeast and mouse U14 RNAs was examined in Saccharomyces cerevisiae. The test RNAs included mouse U14 and several yeast-mouse bi- and tri-partite hybrid RNAs, all transcribed from yeast U14 gene signals. The ability of the heterologous RNAs to provide essential U14 function was assessed in a test strain containing a single glucose-repressible wild-type U14 gene. Mouse U14 was not functional in yeast. However, wild-type growth was supported by hybrid RNAs that included universal sequence elements from either source, two yeast-specific segments and a 5',3' terminal stem domain. The universal sequences include box C, box D and a sequence complementary to 18S rRNA, all shown previously to be required for function of yeast U14. Deletion and substitution mapping defined the yeast-specific elements and showed that a major portion of neighboring non-conserved RNA is dispensable. The results are discussed with a view to defining a minimal consensus U14 molecule.