| Citation | Guest is distinguished for his application of mutant and genetic approaches in defining the biochemistry, genetic organisation and expression of central anabolic and catabolic pathways of bacteria, in particular the tricarboxylic acid cycle (and related functions) in aerobic and anaerobic metabolism. This has led to his development of strategies for cloning the genes encoding the 2-oxo-acid dehydrogenase complexes and other key enzymes such as citrate synthase, succinate dehydrogenase, fumarate reductase and fumarase thus exposing them to detailed analyses of their DNA sequences, their expression and, where applicable, their assembly into functional membrane-bound complexes. In addition, by gene-cloning and sequence analysis he has discovered a new regulatory protein (Fnr) which is essential for the expression of many anaerobic respiratory functions, thus opening the way for identifying effector(s) that regulate(s) anaerobic metabolism by signalling the redox status of the cell. The results of these fundamental studies are of direct relevance to future fermentation technology. |