Action of a minimal contractile bactericidal nanomachine.
NATURE(2020)
摘要
The authors report near-atomic resolution structures of the R-type bacteriocin from Pseudomonas aeruginosa in the pre-contraction and post-contraction states, and these structures provide insight into the mechanism of action of molecular syringes. R-type bacteriocins are minimal contractile nanomachines that hold promise as precision antibiotics(1-4). Each bactericidal complex uses a collar to bridge a hollow tube with a contractile sheath loaded in a metastable state by a baseplate scaffold(1,2). Fine-tuning of such nucleic acid-free protein machines for precision medicine calls for an atomic description of the entire complex and contraction mechanism, which is not available from baseplate structures of the (DNA-containing) T4 bacteriophage(5). Here we report the atomic model of the complete R2 pyocin in its pre-contraction and post-contraction states, each containing 384 subunits of 11 unique atomic models of 10 gene products. Comparison of these structures suggests the following sequence of events during pyocin contraction: tail fibres trigger lateral dissociation of baseplate triplexes; the dissociation then initiates a cascade of events leading to sheath contraction; and this contraction converts chemical energy into mechanical force to drive the iron-tipped tube across the bacterial cell surface, killing the bacterium.
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关键词
Bacterial structural biology,Cryoelectron microscopy,Science,Humanities and Social Sciences,multidisciplinary
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