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Ionel, A, Velázquez-Muriel, JA, Luque, D, Cuervo, A, Castón, JR, Valpuesta, JM, Martín-Benito, J and Carrascosa, JL (2011) Molecular rearrangements involved in the capsid shell maturation of bacteriophage T7. J. Biol. Chem. 286:234-42

Maturation of dsDNA bacteriophages involves assembling the virus prohead from a limited set of structural components followed by rearrangements required for the stability that is necessary for infecting a host under challenging environmental conditions. Here, we determine the mature capsid structure of T7 at 1 nm resolution by cryo-electron microscopy and compare it with the prohead to reveal the molecular basis of T7 shell maturation. The mature capsid presents an expanded and thinner shell, with a drastic rearrangement of the major protein monomers that increases in their interacting surfaces, in turn resulting in a new bonding lattice. The rearrangements include tilting, in-plane rotation, and radial expansion of the subunits, as well as a relative bending of the A- and P-domains of each subunit. The unique features of this shell transformation, which does not employ the accessory proteins, inserted domains, or molecular interactions observed in other phages, suggest a simple capsid assembling strategy that may have appeared early in the evolution of these viruses.

PubMed PMC3012979 Online version:10.1074/jbc.M110.187211

Bacteriophage T7/metabolism; Bacteriophage T7/physiology; Capsid/chemistry; Capsid/metabolism; Capsid Proteins/chemistry; Capsid Proteins/metabolism; Cryoelectron Microscopy; Models, Molecular; Protein Structure, Tertiary