Bacteria can produce membranous nanotubes that mediate contact-dependent exchange of molecules among bacterial cells. However, it is unclear how nanotubes cross the cell wall to emerge from the donor or to penetrate into the recipient cell. Here, we report that Bacillus subtilis utilizes cell wall remodeling enzymes, the LytC amidase and its enhancer LytB, for efficient nanotube extrusion and penetration. Nanotube production is reduced in a lytBC mutant, and the few nanotubes formed appear deficient in penetrating into target cells. Donor-derived LytB molecules localize along nanotubes and on the surface of nanotube-connected neighbouring cells, primarily at sites of nanotube penetration. Furthermore, LytB from donor B. subtilis can activate LytC of recipient bacteria from diverse species, facilitating cell wall hydrolysis to establish nanotube connection. Our data provide a mechanistic view of how intercellular connecting devices can be formed among neighbouring bacteria.
Bibliographical noteFunding Information:
We thank E. Blayvas and A. Ben-Hur (Hebrew University, Israel) for help with XHR-SEM. We are grateful to A. Rouvinski (Hebrew University, Israel) and members of the Ben-Yehuda and Rosenshine laboratories for valuable discussions. This work was supported by the European Research Council (ERC) Advanced Grant (339984), and the NSF/BSF-United States-Israel Binational Science Foundation (2017672) awarded to S.B.-Y., and the ERC Synergy grant (810186) awarded to S.B.-Y. and I.R.
© 2020, The Author(s).