Multiple functional roles of the accessory I-domain of bacteriophage P22 coat protein revealed by NMR structure and CryoEM modeling

Alessandro A Rizzo; Margaret M Suhanovsky; Matthew L Baker; LaTasha C R Fraser; Lisa M Jones; Don L Rempel; Michael L Gross; Wah Chiu; Andrei T Alexandrescu; Carolyn M Teschke

doi:10.1016/j.str.2014.04.003

Multiple functional roles of the accessory I-domain of bacteriophage P22 coat protein revealed by NMR structure and CryoEM modeling

Structure. 2014 Jun 10;22(6):830-41. doi: 10.1016/j.str.2014.04.003. Epub 2014 May 15.

Affiliations

¹ Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
² Verna and Marrs McLean Department of Biochemistry and Molecular Biology, National Center for Macromolecular Imaging, Baylor College of Medicine, Houston, TX 77030, USA.
³ Department of Chemistry, Washington University in St. Louis, St. Louis, MO 63130, USA.
⁴ Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA. Electronic address: andrei.alexandrescu@uconn.edu.
⁵ Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA; Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA. Electronic address: teschke@uconn.edu.

Abstract

Some capsid proteins built on the ubiquitous HK97-fold have accessory domains imparting specific functions. Bacteriophage P22 coat protein has a unique insertion domain (I-domain). Two prior I-domain models from subnanometer cryoelectron microscopy (cryoEM) reconstructions differed substantially. Therefore, the I-domain's nuclear magnetic resonance structure was determined and also used to improve cryoEM models of coat protein. The I-domain has an antiparallel six-stranded β-barrel fold, not previously observed in HK97-fold accessory domains. The D-loop, which is dynamic in the isolated I-domain and intact monomeric coat protein, forms stabilizing salt bridges between adjacent capsomers in procapsids. The S-loop is important for capsid size determination, likely through intrasubunit interactions. Ten of 18 coat protein temperature-sensitive-folding substitutions are in the I-domain, indicating its importance in folding and stability. Several are found on a positively charged face of the β-barrel that anchors the I-domain to a negatively charged surface of the coat protein HK97-core.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Bacteriophage P22 / chemistry*
Bacteriophage P22 / ultrastructure*
Capsid Proteins / chemistry*
Capsid Proteins / ultrastructure*
Cryoelectron Microscopy
Models, Molecular
Molecular Dynamics Simulation
Nuclear Magnetic Resonance, Biomolecular
Protein Structure, Quaternary
Protein Structure, Tertiary
Protein Subunits
Static Electricity

Substances

Capsid Proteins
Protein Subunits

Multiple functional roles of the accessory I-domain of bacteriophage P22 coat protein revealed by NMR structure and CryoEM modeling

Authors

Affiliations

Abstract

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MeSH terms

Substances

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