Pseudouridine (Ψ) is one of the most common RNA modifications in human cells. Made to multiple types of RNA by pseudouridine synthases (PUSs), the modifications play an important role in stabilizing RNAs and ensuring their appropriate splicing and translation into proteins. PUS enzymes are increasingly recognized as key players in genetic diseases, including cancer, but their specific biological roles are in most cases undefined. To chart the universe of Ψ modifications and their various PUS authors, researchers led by Ludwig Oxford’s Chunxiao Song and Parinaz Mehdipour generated knockouts and knockdowns of individual PUS enzymes and mapped the resulting Ψ profiles using a sequencing method developed in the Song lab known as BACS (for 2-bromoacrylamide-assisted cyclization sequencing). BACS converts Ψ to C mutations in RNAs, enabling direct, quantitative, base-resolution sequencing of the modification. Chunxiao, Parinaz and their colleagues reported in an October publication in Nature Cell Biology several previously unknown transfer (t) RNA targets of various PUS enzymes and showed that a pair of them—TRUB1 and PUS10—redundantly catalyze the tightly conserved Ψ55 modification, which is essential to tRNA structure and ribosome binding. They reported in this paper the first comprehensive map of PUS-dependent modifications in human tRNAs that links each PUS enzyme to its tRNA targets, effectively creating a reference map to guide studies of the roles these enzymes play in health and disease.
A comprehensive tRNA pseudouridine map uncovers targets dependent on human stand-alone pseudouridine synthases
Nature Cell Biology, 2025 October 24