Thanks for using annotatr. At the moment you need to provide S. Cerevisiae annotations as custom annotations with the read_annotations() function. I am currently working on a more general function to convert any GRanges resource in the AnnotationHub package into an annotation for use in annotatr. If S. Cerevisiae annotations are in the Hub as GRanges, you'll be able to use those. I'll update this thread when that function is implemented, tested, and released.