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bioRxiv · 10.1101/420992

How phage L capsid decoration protein distinguishes between nearly identical binding sites on an icosahedral virion

Newcomer, R. L.·Schrad, J. R.·Gilcrease, E. B.·Casjens, S. R.·Feig, M.·Teschke, C. M.·Alexandrescu, A.·Parent, K. N.
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Abstract

The major coat proteins of dsDNA tailed phages and herpesviruses form capsids by a mechanism that includes active packaging of the dsDNA genome into a precursor procapsid, followed by expansion and stabilization of the capsid. These viruses have evolved diverse strategies to fortify their capsids, such as non-covalent binding of auxiliary "decoration" (Dec) proteins. The Dec protein from the P22-like phage L has a highly unusual binding strategy that precisely distinguishes between nearly identical three-fold and quasi-three-fold sites of the icosahedral capsid. Cryo-electron microscopy and three-dimensional image reconstruction were employed to determine the structure of native phage L particles. NMR was used to determine the structure/dynamics of Dec in solution. Lastly, the NMR structure and the cryo-EM density envelope were combined to build a model of the capsid-bound Dec trimer. Key regions that modulate the binding interface were verified by site-directed mutagenesis.

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Newcomer, R. L., Schrad, J. R., Gilcrease, E. B., Casjens, S. R., Feig, M., Teschke, C. M., Alexandrescu, A., Parent, K. N.. 2018-09-18. How phage L capsid decoration protein distinguishes between nearly identical binding sites on an icosahedral virion. https://doi.org/10.1101/420992

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