The objective of the proposed work is to determine the mechanism of particle maturation for the HK97 virus, a highly accessible model system. Virtually all complex viruses initially assemble into non-infectious, often fragile, particles that are called provirions. Encoded in their structure is a program that directs particle conformational changes leading to a robust, infectious virion. Six different intermediates of this maturation have been isolated for HK97. Previous support for this work lead to the near-atomic resolution structures of three intermediates and the discovery that early maturation is an exothermic process and later maturation is driven by a Brownian ratchet mechanism. We now propose to determine the structures of three more intermediates and to study the transitions between all of the intermediates with single particle and ensemble methods. Our goal is to understand how the expression of two viral gene products creates a meta-stable particle that releases ~20kCal/mole of energy in the initial step of maturation and then proceeds by biasing thermal fluctuations with a covalent cross-link to complete the maturation process. We are also investigating the use of the mature particles as a potential delivery system for drugs in nano medicine.

Public Health Relevance

Project Narrative Virus maturation is virtually universal among complex viruses and is a worthy target for antiviral therapy. It is, however, very difficult to study because purified virions are fully mature. Grasping the details of the process requires accessible model systems where intermediates can be isolated and studied, as well as the transitions between them. HK97 is such a system and we are exploiting it to understand the structural, kinetic and thermodynamic parameters of particle maturation.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-BCMB-B (03))
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Park, Eun-Chung
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Scripps Research Institute
La Jolla
United States
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Veesler, David; Khayat, Reza; Krishnamurthy, Srinath et al. (2014) Architecture of a dsDNA viral capsid in complex with its maturation protease. Structure 22:230-7
Lander, Gabriel C; Johnson, John E; Rau, Donald C et al. (2013) DNA bending-induced phase transition of encapsidated genome in phage ?. Nucleic Acids Res 41:4518-24
Johnson, John E (2013) Confessions of an icosahedral virus crystallographer. Microscopy (Oxf) 62:69-79
Veesler, David; Johnson, John E (2013) Cystovirus maturation at atomic resolution. Structure 21:1266-8
Snijder, Joost; Rose, Rebecca J; Veesler, David et al. (2013) Studying 18 MDa virus assemblies with native mass spectrometry. Angew Chem Int Ed Engl 52:4020-3
Veesler, David; Johnson, John E (2012) Virus maturation. Annu Rev Biophys 41:473-96
Hendrix, Roger W; Johnson, John E (2012) Bacteriophage HK97 capsid assembly and maturation. Adv Exp Med Biol 726:351-63
Roos, Wouter H; Gertsman, Ilya; May, Eric R et al. (2012) Mechanics of bacteriophage maturation. Proc Natl Acad Sci U S A 109:2342-7
Lander, Gabriel C; Baudoux, Anne-Claire; Azam, Farooq et al. (2012) Capsomer dynamics and stabilization in the T = 12 marine bacteriophage SIO-2 and its procapsid studied by CryoEM. Structure 20:498-503
Speir, Jeffrey A; Johnson, John E (2012) Nucleic acid packaging in viruses. Curr Opin Struct Biol 22:65-71

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