3HJY ISOMERASE/RNA, PROTEIN-RNA COMPLEX, BOX H/ACA, RIBONUCLEOPROTEIN PARTICLES, RNP, PSEUDOURIDINE SYNTHASE, PSEUDOURIDYLASE, PSEUDOURIDYLATION, RNA EDITING, POST-TRANSCRIPTIONAL MODIFICATION, ISOMERASE, TRNA PROCESSING, RIBONUCLEOPROTEIN, RIBOSOME BIOGENESIS, RRNA PROCESSING, ISOMERASE/RNA COMPLEX STRUCTURE OF A FUNCTIONAL RIBONUCLEOPROTEIN PSEUDOURIDINE SYNTHASE BOUND TO A SUBSTRATE RNA