John Derek Smith

Abstract In the 1950s and 1960s John Smith pioneered the studies of RNA sequence and function and, in doing so, laid the foundations for the subsequent immense flowering and power of genomic sequencing as it is practised today. First and foremost John was a meticulous experimentalist who enjoyed working at the bench. He was most interested in the fundamental chemistry of nucleic acid bases and their biological significance. To this end he developed a suite of analytical techniques, some of which were later applied to the sequencing of both RNA and DNA. Among the most important of his discoveries was the identification of DNA base modifications and their role in the bacterial defence modification/restriction system—an early example demonstrating the mechanism of DNA recognition by the now universally used DNA restriction enzymes. Other crucial contributions included the demonstrations that poliovirus RNA was translated as a messenger RNA in a polysome and that a mutation in a transfer RNA gene could alter the underlying genetic code by allowing a putative chain termination codon to be translated as an amino acid. As a scientific mentor he possessed an unassuming yet rigorous approach encouraging the development of independent thinking in his students.