A dynamin-like protein involved in bacterial cell membrane surveillance under environmental stress

Bacteria are exposed to a myriad of different environmental stresses, including membrane-targeting antibiotics and phage predation. Consequently, they have evolved mechanisms to counteract these stresses and ensure survival. Exposure to antibiotics often causes pleiotropic phenotypes and the exact cellular response mechanisms are not always understood. Many membrane-targeting antibiotics are able to impair membrane integrity by pore formation. It is therefore not surprising that bacteria have systems to ensure membrane integrity. Here, we describe the function of a bacterial dynamin-like protein, DynA from Bacillus subtilis, to be part of a membrane surveillance system that provides relative resistance to pore formation during membrane stress. Strains lacking dynAshow impaired growth in the presence of membrane stress-inducing antibiotics and are more sensitive to phage infection compared to wild-type B. subtilis. In vitro analysis using sophisticated lipid-mixing and content-mixing assays we show that DynA is able to tether and fuse membranes in trans. High resolution imaging shows that DynA is highly dynamic on the membrane, but forms stable protein cluster during stress, likely at the sites of membrane lesions. Phage infection assays reveal that DynA does not interfere with phage replication, but prevents efficient phage release. This slows down the spreading of the infection in bacterial communities. Bacterial dynamins thus provide herd immunity to phage infection. Our data show how versatile bacterial dynamins are used to counteract environmental stresses.

For link and password, please contact Britta Baron (baron@evolbio.mpg.de).