Contact-dependent killing byCaulobacter crescentusvia cell surface-associated, glycine zipper proteins.
Most bacteria are in fierce competition with other species for limited nutrients. Some bacteria can kill nearby cells by secreting bacteriocins, a diverse group of proteinaceous antimicrobials. However, bacteriocins are typically freely diffusible, and so of little value to planktonic cells in aqueous environments. Here, we identify an atypical two-protein bacteriocin in the α-proteobacteriumCaulobacter crescentusthat is retained on the surface of producer cells where it mediates cell contact-dependent killing. The bacteriocin-like proteins CdzC and CdzD harbor glycine-zipper motifs, often found in amyloids, and CdzC forms large, insoluble aggregates on the surface of producer cells. These aggregates can drive contact-dependent killing of other organisms, orCaulobactercells not producing the CdzI immunity protein. The Cdz system uses a type I secretion system and is unrelated to previously described contact-dependent inhibition systems. However, Cdz-like systems are found in many bacteria, suggesting that this form of contact-dependent inhibition is common.
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.|Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States.|Graduate Program in Microbiology, Massachusetts Institute of Technology, Cambridge, United States.
Leonor
L
García-Bayona
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.
Monica S
MS
Guo
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.|Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, United States.
Michael T
0000-0002-8288-7607
MT
Laub
D000898:Antibiosis; D001426:Bacterial Proteins / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000502:physiology*; D008565:Membrane Proteins / Q000378:metabolism*; D050296:Microbial Viability; D021381:Protein Transport
D001426:Bacterial Proteins; D001430:Bacteriocins; D008565:Membrane Proteins
Caulobacter crescentus; bacteriocins; contact-dependent inhibition; infectious disease; microbiology; type I secretion system