7YPX

Cyanophage Pam3 fiber

Summary for 7YPX

• Entry DOI: 10.2210/pdb7ypx/pdb
• EMDB information: 34017
• Descriptor: Pam3 tail fiber proreins, tail fiber chaperone (2 entities in total)
• Functional Keywords: fiber, virus, viral protein
• Biological source: uncultured cyanophage; More
• Total number of polymer chains: 6
• Total formula weight: 137524.60

Authors

Wei, Z.L.,Jiang, Y.L.,Zhou, C.Z. (deposition date: 2022-08-04, release date: 2022-11-09, Last modification date: 2024-07-03)

Primary citation

Wei, Z.L.,Yang, F.,Li, B.,Hou, P.,Kong, W.W.,Wang, J.,Chen, Y.,Jiang, Y.L.,Zhou, C.Z.
Structural Insights into the Chaperone-Assisted Assembly of a Simplified Tail Fiber of the Myocyanophage Pam3.
Viruses, 14:-, 2022

PubMed Abstract: At the first step of phage infection, the receptor-binding proteins (RBPs) such as tail fibers are responsible for recognizing specific host surface receptors. The proper folding and assembly of tail fibers usually requires a chaperone encoded by the phage genome. Despite extensive studies on phage structures, the molecular mechanism of phage tail fiber assembly remains largely unknown. Here, using a minimal myocyanophage, termed Pam3, isolated from Lake Chaohu, we demonstrate that the chaperone gp25 forms a stable complex with the tail fiber gp24 at a stoichiometry of 3:3. The 3.1-Å cryo-electron microscopy structure of this complex revealed an elongated structure with the gp25 trimer embracing the distal moieties of gp24 trimer at the center. Each gp24 subunit consists of three domains: the N-terminal α-helical domain required for docking to the baseplate, the tumor necrosis factor (TNF)-like and glycine-rich domains responsible for recognizing the host receptor. Each gp25 subunit consists of two domains: a non-conserved N-terminal β-sandwich domain that binds to the TNF-like and glycine-rich domains of the fiber, and a C-terminal α-helical domain that mediates trimerization/assembly of the fiber. Structural analysis enabled us to propose the assembly mechanism of phage tail fibers, in which the chaperone first protects the intertwined and repetitive distal moiety of each fiber subunit, further ensures the proper folding of these highly plastic structural elements, and eventually enables the formation of the trimeric fiber. These findings provide the structural basis for the design and engineering of phage fibers for biotechnological applications.

PubMed: 36298815
DOI: 10.3390/v14102260

Experimental method

ELECTRON MICROSCOPY (3.12 Å)