Former Chair of the Biophysics Program at Harvard University

Our research program currently has two major areas of focus: 1) Structural and biochemical characterization of the cell entry pathway of polio and related viruses, 2) Structural characterization of components of the Herpes virus replication complex and nuclear egress complex.

 1) Structural and biochemical dissection of the cell entry pathway of polio and related picornaviruses. Because non-enveloped viruses such as poliovirus lack a membrane they cannot use membrane fusion to gain entry to the cell and must instead provide a mechanism for translocation of either the viral genome or the entire viral nucleocapsid across the cell membrane.  The mechanisms responsible for this translocation process are poorly understood.  Previous studies have shown that attachment of poliovirus to its receptor leads to conformational changes that result in the insertion of normal internal viral protein sequences in the membrane and the production of channels.  This has led to a working model in which the channels are proposed to form translocation pores that allow the RNA to be moved across the cell membrane to initiate infection.  This project includes a combination of x-ray crystallographic and electron microscopic characterization of the structures of virus receptor complexes and cell entry intermediates in solution.  We have also developed a receptor-decorated liposome model for biochemical and structural characterization of the entry pathway in the context of membranes.  We have shown that the liposome model recapitulates the structural changes induced during infection and supports the translocation of the viral RNA from the interior of the particle, across the liposome membrane and into the lumen of the liposome, and demonstrated that RNA translocation in the liposome model and during infection is resistant to RNAse.  We are using a combination of electron cryotomography, high-resolution electron cryomicroscopy, single particle light microscopy and biochemical approaches to characterize the structure and kinetics of the RNA translocation machinery.

2) In collaboration with Don Coen we have initiated a program of structural studies of proteins essential for replication in herpes viruses.  The DNA replication in herpes viruses includes at least seven proteins, and our ultimate goal in this collaboration is to develop a picture of the complete replication complex.  Our initial focus has been on the interaction between the DNA polymerase of HSV1 and an accessory protein, UL42, which is required for processive DNA synthesis.  We have solved the structure of a complex between UL42 and the minimal C-terminal domain of the polymerase, and have recently solved the structure of the homologous protein UL44 from cytomegalovirus with and without the C-terminal peptide from the CMV polymerase, and the structure of the homologous protein PF8 from the Kaposi’s sarcoma-associated herpes virus KSHV.   More recently we have also begun to characterize the structure and function of the nuclear egress complex.  This heterodimeric complex facilitates the egress of assembled capsids from the nucleus by a process of budding through the inner membrane then fusing with the out nuclear membrane.   The structures derived from these studies are being used to guide efforts to develop inhibitors as candidate antivirals.

Selected Publications:

Baltz, J.L., Filman,  D.J., Ciustea, M., Silverman, J.E., Lautenschlager, C.L., Coen, D.M., Ricciardi, R.P., Hogle, J.M (2009). The crystal structure of PF-8, the DNA polymerase accessory subunit from Kaposi's sarcoma-associated herpesvirus.  J. Virol. 83:12215-28. PMID: 19759157, PMCID: PMC2786759

Sam, M.D., Evans, B.T., Coen, D.M., and Hogle, J.M. (2009) Biochemical, biophysical, and mutational analyses of subunit interactions of the human cytomegalovirus nuclear egress complex. J Virol 83: 2996-3006. PMID: 19153235, PMCID: PMC2655548

Levy, H. C., Bostina, M., Filman, D. J., and Hogle, J. M. (2010). Catching a virus in the act of RNA-release: a novel poliovirus uncoating intermediate characterized by cryoelectron microscopy, J Virol. 84:4426-41. PMID: 20181687, PMCID: PMC2863768

Bostina, M., Levy, H., Filman, D.J. and Hogle, J.M. (2011) Poliovirus RNA is released from the capsid near a twofold symmetry axis.  J. Virol. 85:776-83.  PMID: 20980499, PMCID: PMC3020038

Strauss, M., Levy, H., Bostina, M., Filman, D.J., and Hogle, J.M.  (2013). RNA transfer from poliovirus 135S particles across membranes is mediated by long umbilical connectors. J Virol 87: 3903-3914. PMID: 23365424, PMC3624230

Butan, C., Filman, D.J., and Hogle, J.M. (2014). Cryo-electron microscopy reconstruction shows poliovirus 135S particle poised for membrane interaction and RNA release.  J. Virol. 88:1758-70. PMID: 24257617, PMC3911577