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Publication Abstract from PubMed

Tail tube assembly is an essential step in the lifecycle of long-tailed bacteriophages. Limited structural and biophysical information has impeded an understanding of assembly and stability of their long, flexible tail tubes. The hyperthermophilic phage P74-26 is particularly intriguing as it has the longest tail of any known virus (nearly 1 mum) and is the most thermostable known phage. Here, we use structures of the P74-26 tail tube along with an in vitro system for studying tube assembly kinetics to propose the first molecular model for the tail tube assembly of long-tailed phages. Our high resolution cryo-EM structure provides insight into how the P74-26 phage assembles through flexible loops that fit into neighboring rings through tight "ball-and-socket"-like interactions. Guided by this structure, and in combination with mutational, light scattering, and molecular dynamics simulations data, we propose a model for the assembly of conserved tube-like structures across phage and other entities possessing Tail Tube-like proteins. We propose that formation of a full ring promotes the adoption of a tube elongation-competent conformation among the flexible loops and their corresponding sockets, which is further stabilized by an adjacent ring. Tail assembly is controlled by the cooperative interaction of dynamic intra- and inter-ring contacts. Given the structural conservation among tail tube proteins and tail-like structures, our model can explain the mechanism of high-fidelity assembly of long, stable tubes.

Conformational dynamics control assembly of an extremely long bacteriophage tail tube.,Agnello E, Pajak J, Liu X, Kelch BA J Biol Chem. 2023 Feb 13:103021. doi: 10.1016/j.jbc.2023.103021. PMID:36791911^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.