Contact-Dependent Killing by Caulobacter Crescentus via 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 aqueo...
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
eLife Sciences Publications, Ltd.
2017
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| Online Access: | http://hdl.handle.net/1721.1/109871 https://orcid.org/0000-0002-6720-2323 https://orcid.org/0000-0002-8288-7607 |
| Summary: | 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-proteobacterium Caulobacter crescentus that 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, or Caulobacter cells 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. |
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