| Citation | Ellis' early work largely concerned sulphur metabolism in bacteria and plants. He made definitive studies of cycloheximide as an inhibitor of protein synthesis on prokaryotic ribosomes. Since 1970 he has contributed largely to our understanding of the interaction of nuclear and chloroplast genomes to produce the chloroplast enzyme ribulose biphosphate carboxylase/oxygenase, a key enzyme of photosynthesis and perhaps the most abundant protein in the world. The enzyme consists of large subunits encoded and synthesised within the chloroplast, and small subunits encoded in the nucleus and synthesised within the chloroplast, and small subunits encoded in the nucleus and synthesised by cytoplasmic ribosomes. Ellis originated the method of using light as an energy source for intact isolated chloroplasts as a means of identifying the function of chloroplast ribosomes and of chloroplast DNA. He made the first demonstration of (1) an identified polypeptide made by chloroplast ribosomes (the carboxylase large subunit), (2) a high molecular weight transcript of chloroplast DNA containing ribosomal RNA sequences and (3) in vitro translation of mRNA for a plant enzyme. Ellis further showed that the small subunit made by cytoplasmic ribosomes enters the chloroplasts by a novel post-translational mechanism. He is currently extending his efforts to a study of the control mechanisms involved in coordinating protein synthesis in the green plant. Ellis' work is characterised by his flair for experimentation and the application of well thought out ideas. His work is a major advance and has led to a great increase in research by other laboratories using in vitro methods to investigate the chloroplast genetic system. |