Bacterial social networks: structure and composition of Myxococcus xanthus outer membrane vesicle chains

Abstract

Summary The social soil bacterium, Myxococcus xanthus, displays a variety of complex and highly coordinated behaviors, including social motility, predatory rippling and fruiting body formation. Here we show that M. xanthus cells produce a network of outer membrane extensions in the form of vesicles and vesicle chains that interconnect cells. We observed peritrichous display of vesicles and vesicle chains and increased abundance in biofilms compared to planktonic cultures. By applying a range of imaging techniques, including 3D Focused Ion Beam Scanning Electron Microscopy (FIB/SEM), we determined these structures to range between 30-60 nm in width and up to 5 μm in length. Purified vesicle chains consist of typical M. xanthus lipids, fucose, mannose, N-acetylglucosamine (GlcNAc) and N-acetylgalactoseamine (GalNAc) carbohydrates and a small set of cargo protein. The protein content includes CglB and Tgl membrane proteins transferred in a contact-dependent manner. Most significantly, the 3D organization of cells within biofilms indicates that cells are connected via an extensive network of membrane extensions that may connect cells at the level of the periplasmic space. Such a network would allow the transfer of membrane proteins and other molecules between cells, and likely provides a mechanism for the coordination of social activities.

Metabolic cross-feeding via intercellular nanotubes among bacteria

“…All samples were spiked with 13 C, 15 N-labelled amino acids (algal amino acids 13 C, 15 N, Isotec) at a concentration of 10 mg of the mix per ml. Trp was quantified using 13 C, 15 N-Phe as internal standard applying a response factor of 0.42.…”

“…Such mechanisms include, for example, the production of outer membrane vesicles, as they are used by many bacterial species to deliver cargo to other cells [12][13][14][15][16] . Alternatively, bacterial cells may connect via channels 17 , nanotubes 18 , pili 19 or transiently fuse their outer membrane 20 to transfer cytoplasmic components or outer membrane materials.…”

“…Second, chemical signals that help to coordinate social activities within microbial communities are trafficked between cells 16 . Third, proteins can be transferred between cells 18,20 , which are involved in social movement 14 or serve predatory bacteria as interspecific killing factors 15 . Another possibility, which remains virtually unexplored, is the utilization of intercellular connections to transfer nutrients between bacterial cells.…”

Microbial nanowires: an electrifying tale

“…Unlike pili and flagella, which are mostly homopolymers of a single subunit type, MNWs in S. oneidensis are a concoction of different cytochromes and periplasmic as well as outer membrane components. The formation of outer membrane vesicle chains and tubes has been reported in Myxococcus xanthus (Remis et al, 2014;Wei et al, 2014). Also, the ability of peptide nanotubes to convert into vesicles and vice versa is well known (Scanlon et al (2016) & Aggeli, 2008).…”

The Spatiality of Being

“…In other words only those insects in proximity to some cue, and thus nearby in space-time, will be impinged upon and steered to act in some way. Myxococcus xanthusis, a species of bacteria, has received much interest of late because of its social behaviour and complex spatial formations (Remis et al 2014). The components constituting such systems have relevance and their interactions are deictic, effecting meaning and direction.…”