The road to RNase P.

In 1989, Sidney Altman and Thomas R. Cech shared the Nobel Prize in Chemistry for their discovery of catalytic properties of RNA. Cech was studying the splicing of RNA in a unicellular organism called Tetrahymena thermophila. He found that the precursor RNA could splice in vitro in the absence of proteins. Altman studied ribonuclease P (RNase P), a ribonucleoprotein that is a key enzyme in the biosynthesis of tRNA. RNase P is an RNA processing endonuclease that specifically cleaves precursors of tRNA, releasing 5' precursor sequences and mature tRNAs. RNase P is involved in processing all species of tRNA and is present in all cells and organelles that carry out tRNA synthesis. What follows is a personal recollection by Altman of how he came to study this remarkable enzyme.