THE YEAST BDF1 GENE ENCODES A TRANSCRIPTION FACTOR INVOLVED IN THE EXPRESSION OF A BROAD CLASS OF GENES INCLUDING SNRNAS

While screening for genes that affect the synthesis of yeast snRNPs, w e identified a thermosensitive mutant that abolishes the production of a reporter snRNA at the non-permissive temperature. This mutant defin es a new gene, named BDF1. In a bdf1-1 strain, the reporter snRNA synt hesized before the temperature shift remains stable at the non-permiss ive temperature. This demonstrates that the BDF1 gene affects the synt hesis rather than the stability of the reporter snRNA and suggests tha t the BDF1 gene encodes a transcription factor. BDF1 is present in sin gle copy on yeast chromosome XII, and is important for normal vegetati ve growth but not essential far cell viability. bdf1 null mutants shar e common phenotypes with several mutants affecting general transcripti on and are defective in snRNA production. BDF1 encodes a protein of 68 7 amino-acids containing two copies of the bromodomain, a motif also p resent in other transcription factors as well as a new conserved domai n, the ET domain, also present in Drosophila and human proteins.