Nobel laureate Sir Richard J. Roberts (UK/USA) focuses in his presentation on bacterial DNA methyltransferases (MTases), which are best known as orphan enzymes such as the Dam methylase of E. coli or as components of restriction-modification (RM) systems. Until recently, rigorously determining the specificity of MTases has been a tedious process. When they were components of Type II restriction systems it has been assumed that the MTases would have the same specificity as the cognate restriction enzyme. For Type I and Type III RM systems specificity determination was rarely attempted.

With the advent of SMRT sequencing from Pacific Biosciences this situation has changed dramatically. Now it has become very simple to determine MTase recognition sequences both for individual MTases cloned in plasmids and also for whole bacterial genomes. This offers new insights into the functioning of bacteria and has led to the discovery of many novel MTases with unexpected properties. A new door on bacterial life has been opened and raises many questions.

Sir Richard J. Roberts

is the Chief Scientific Officer at New England Biolabs, Beverly, Massachusetts.  He was awarded the 1993 Nobel Prize in Physiology or Medicine with Phillip Allen Sharp for the discovery of introns in eukaryotic DNA and the mechanism of gene-splicing.