Conjugative plasmids are important drivers of bacterial evolution. Most
plasmids lack genes for conjugation and characterized origins of transfer
(oriT), which has hampered our understanding of plasmid mobility. Here
we used bioinformatic analyses to characterize occurrences of known oriT
families across 38,057 plasmids, confirming that most conjugative and
mobilizable plasmids lack identifiable oriTs. Recognizable oriT sequences
tend to be intergenic, upstream of relaxase genes and specifically
associated with relaxase types. We used these criteria to develop a
computational method to search for and identify 21 additional families of
oriT-containing sequences in plasmids from the pathogens Escherichia coli,
Klebsiella pneumoniae and Acinetobacter baumannii. Sequence analyses
found 3,072 occurrences of these oriT-containing sequences across 2,976
plasmids, many of which encoded antimicrobial resistance genes. Six
candidate oriT-containing sequences were validated experimentally and
were shown to facilitate conjugation in E. coli. These findings expand our
understanding of plasmid mobility.
To know more about it: Ares-Arroyo, Nucci, Rocha, Nature Microbiology, 2024
