Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
Biol Lett. 2023 Mar;19(3):20220376. doi: 10.1098/rsbl.2022.0376. Epub 2023 Mar 1.
To persist, a plasmid relies on being passed on to a daughter cell, but this does not always occur. Plasmids with post-segregational killing (PSK) systems kill a daughter cell if the plasmid has not been passed on. By killing the host, it also kills competing plasmids in the same host, something competing plasmids without a similar system cannot do. Accordingly, plasmids with PSK systems can displace other plasmids. In nature, plasmids with and without PSK systems coexist and prior theory has suggested this is expected to be very rare or unstable, such that one or the other type of plasmid eventually takes over. Here, we show that if there is spatial structure and plasmids confer benefits to hosts, coexistence of plasmids occurs broadly. Often plasmids confer benefits (even ones with a PSK system) and bacteria are often spatially structured. So, our results may be generally applicable.
为了持续存在，质粒依赖于被传递给子细胞，但这并不总是发生。具有 继后杀伤（PSK）系统的质粒如果没有被传递，就会杀死子细胞。通过杀死宿主，它还会杀死同一宿主中的竞争质粒，而没有类似系统的竞争质粒则无法做到这一点。因此，具有 PSK 系统的质粒可以取代其他质粒。在自然界中，具有和不具有 PSK 系统的质粒共存，先前的理论表明这种共存应该是非常罕见或不稳定的，以至于一种或另一种类型的质粒最终会接管。在这里，我们表明，如果存在空间结构并且质粒赋予宿主益处，那么质粒的共存就会广泛发生。通常情况下，质粒赋予宿主益处（即使是具有 PSK 系统的质粒），而细菌通常具有空间结构。因此，我们的结果可能具有普遍适用性。
