| Citation | Professor Sherratt has made important contributions towards our understanding of the processes involved in the maintenance and propagation of plasmids and the mobility of transposable elements in bacteria. He identified a protein that controls the number of ColE1-like plasmids in the bacterial cell, and characterised the plasmid site (cer) and the three chromosomal genes whose products are required for stable plasmid inheritance. With his colleagues, he also showed that ColE1-like plasmids devote almost half of their genome (four genes and a transfer origin) to conjugal transfer. He made significant contributions to early methods for transposition and was the first to demonstrate that the transposon, Tn3, transposes replicatively. He identified the five Tn7 transposition functions and has outlined their role in transposition. The more recent work from his group on the mechanisms of site-specific recombination with both the Tn3 resolvase and the ColE1 cer system has revealed how DNA topology and the formation of specific 'synaptic' complexes introduce both directionality and selectivity into DNA rearrangements. |