Mechanisms of plasmid behavioural manipulation

Large conjugative plasmids are key agents of horizontal gene transfer, sharing genetic material within bacterial populations. The classical model of plasmid maintenance suggests that as plasmid carriage is typically costly to the host, plasmid maintenance requires some form of selective environmental advantage, such as antibiotic resistance. However, it is becoming increasingly clear that plasmids have evolved multiple, ingenious ways to manipulate their hosts behaviour that enable them to be maintained and proliferate in the absence of obvious selection pressures. These processes are collectively termed plasmid-chromosome crosstalk (PCC). From the specific regulation of individual chromosomal loci to the global disruption of microbial regulatory networks, PCC regulators can override chromosomally encoded signalling pathways to cause adaptive shifts in their hosts proteome. These mechanisms of bacterial behavioural manipulation can lead to profound changes in the ability of bacteria to interact with their environment and other bacteria, with major implications both for environmental adaptation and clinical infections.