Paul I. Freimuth

Research Interests

One aspect of our research program aims to understand the folding behavior of proteins during overexpression, when molecular chaperone activity may be limiting. Protein overexpression technology has greatly facilitated structural and functional analyses of individual proteins, and it will also be a key technology for large scale characterization of proteomes as planned in the DOE's GTL program, for example. Molecular chaperones promote folding by lowering the free energy barrier to the unfolding of intermediate states. Deficits in chaperone activity therefore can lead to the kinetic trapping of folding intermediates, which eventually may aggregate. Our recent studies suggest that intramolecular electrostatic attractive and repulsive forces may be important factors in determining the stability of folding intermediates. This and other insights into folding pathways should lead to enhanced prediction of protein folding behavior and the development of strategies to optimize protein folding efficiency.

Another aspect of our research program aims to understand the structural basis for protein-protein interactions. As databases of protein structures increase in size and resolution, it may eventually be possible to use this information to aid in the prediction of networks of interacting proteins. We use the interaction of adenovirus with its cellular receptor as an experimental model system. Immunoselective pressure during virus evolution has produced a large number of natural variants that interact with a common molecular target, despite poor conservation of contact residues in the receptor-binding site. We assess the impact of this natural variation on binding affinity and specificity, using Xray crystallography, computational modeling, and directed mutagenesis. Insights from these studies should enhance our ability to predict interactive surfaces and to design systems for novel molecular recognition applications in gene therapy or medical imaging.

Selected Publications

• Freimuth P., Philipson L. and Carson S.D.
  The coxsackievirus and adenovirus receptor.
  Current Topics in Microbiology and Immunology: Group B Coxsackieviruses, S. Tracy, M. S. Oberste, and K. M. Drescher, Editors, Vol. 323, Chapter 4, pp. 67-87, Springer-Verlag Berlin Heidelberg (2008).
• Maye M.M., Freimuth P., and Gang O.
  Adenovirus knob trimers as tailorable scaffolds for nanoscale assembly.
  Small, 4(11):1941-1944 (November, 2008).
• Freimuth P.
  Protein overexpression in mammalian cell lines.
  Genetic Engineering: Principles and Methods, J. K. Setlow, Editor, Vol. 28, pp. 95-104, Springer Science + Business Media, LLC, New York, NY (2007).  PubMed
• Schulz R., Zhang Y.-B., Liu C.-J. and Freimuth P.
  Thiamine diphosphate binds to intermediates in the assembly of adenovirus fiber knob trimers in Escherichia coli.
  Protein Science, 16(12):2684-2693 (2007).  PubMed
• Zhang Y.-B., Kanungo M., Ho A.J., Freimuth P., van der Lelie D., Chen M., Khamis S.M., Datta S.S., Charlie Johnson A.T., Misewich J.A. and Wong S.S.
  Functionalized carbon nanotubes for detecting viral proteins.
  Nano Letters, 7(10):3086-3091 (2007).  PubMed
• Awasthi V.D., Meinken G., Springer K., Srivastava S.C. and Freimuth P.
  Biodistribution of radioiodinated adenovirus fiber protein knob domain after intravenous injection in mice.
  J. Virol., 78(12):6431-6438 (2004).   PubMed   Full Text
• Howitt J., Bewley M., Graziano V., Flanagan J. and P. Freimuth.
  Structural basis for variation in adenovirus affinity for the cellular coxsackievirus and adenovirus receptor.
  J. Biol. Chem., 278(28):26208-15 (2003).   PubMed   Full Text
  PDB files 1P69 1P6A   Jmol viewer
• Zhang Y.-B., Howitt J., McCorkle S., Lawrence P., Springer K. and Freimuth P.
  Protein aggregation during overexpression limited by peptide extensions with large net negative charge.
  Protein Expr Purif., 36(2):207-216 (2004).   PubMed
• Howitt J., Anderson C.W. and FreimuthP.
  Adenovirus interaction with its cellular receptor CAR.
  Curr. Top. Microbiol. Immunol., 272:331-364 (2003).   PubMed
• Walters R.W., Freimuth P., Moninger T.O., Ganske I., Zabner J. and Welsh M.J.
  Adenovirus fiber disrupts CAR-mediated intercellular adhesion allowing virus escape.
  Cell, 110:789-799 (2002).   PubMed
• Anderson C.W., Dunn J.J., Freimuth P.I., Galloway A.M. and Allalunis-Turner M.J.
  Frameshift mutation in PRKDC, the gene for DNA-PKcs, in the DNA repair-defective, human, glioma-derived cell line M059J.
  Radiat. Res., 156:2-9 (2001).   PubMed
• He Y., Chipman P.R., Howitt J., Bator C.M., Whitt M.A., Baker T.S., Kuhn R.J., Anderson C.W., Freimuth P. and Rossmann M.G.
  Interaction of coxsackievirus B3 with the full-length coxsackievirus-adenovirus receptor.
  Nat. Struct. Biol., 8(10):874-878 (2001).   PubMed
  PDB file 1JEW   Jmol viewer
• Thanos P.K., Volkow N.D., Freimuth P., Umegaki H., Ikari H., Roth G., Ingram D.K. and Hitzemann R.
  Overexpression of dopamine D2 receptors reduces alcohol self-administration.
  J. Neurochem., 78:1094-1103 (2001).   PubMed
• Bewley M.C., Springer K., Zhang Y.-B., Freimuth P. and Flanagan J.M.
  Structural analysis of the mechanism of adenovirus binding to its human cellular receptor, CAR.
  Science, 286:1579-1583 (1999).   PubMed   Full Text
  PDB files 1KAC 1NOB   Jmol viewer
• Freimuth P., Springer K., Berard C., Hainfeld J., Bewley M. and Flanagan J.
  Coxsackievirus and adenovirus receptor amino-terminal immunoglobulin V related domain binds adenovirus type 2 and fiber knob from adenovirus type 12.
  J. Virol., 73:1392-1398 (1999).   PubMed   Full Text
• Hainfeld J.F., Liu W., Halsey C.M.R., Freimuth P. and Powell R.D.
  Ni-NTA-gold clusters target His-tagged proteins.
  J. Struct. Biol., 127:185-198 (1999).   PubMed
• Schaack J., Ho W.Y., Tolman S., Ullyat E., Guo X., Frank N., Freimuth P.I., Roovers D.J. and Sussenbach J.S.
  Construction and preliminary characterization of a library of "lethal" preterminal protein mutant adenoviruses.
  J. Virol., 73(11):9599-9603 (1999).   PubMed   Full Text
• Mayr G.A. and Freimuth P.
  A single locus on human chromosome 21 directs the expression of a receptor for adenovirus type 2 in mouse A9 cells.
  J. Virol., 71:412-418 (1997).   PubMed   Full Text
• Zabner J., Freimuth P., Puga A., Fabrega A. and Welsh M.J.
  Lack of high affinity fiber receptor activity explains the resistance of ciliated airway epithelia to adenovirus infection.
  J. Clin. Invest., 100:1144-1149 (1997).   PubMed   Full Text
• Freimuth P.
  A human cell line selected for resistance to adenovirus infection has reduced levels of the virus receptor.
  J. Virol., 70:4081-4085 (1996).   PubMed   Full Text
• Agger R. and Freimuth P.
  Purification and cDNA sequence of a murine protein homologous to the human p62 tyrosine phosphoprotein that associates with the Ras GTPase-acivating protein p120 GAP.
  Gene, 158:307-308 (1995).   PubMed
• Bai M., Campisi L., and Freimuth P.
  Vitronectin receptor antibodies inhibit infection of HeLa and A549 cells by adenovirus type 12 but not by adenovirus type 2.
  J. Virol., 68:5925-5932 (1994).   PubMed   Full Text
• Bai M., Harfe B. and Freimuth P.
  Mutations that alter an Arg-Gly-Asp (RGD) sequence in the adenovirus type 2 penton base protein abolish its cell-rounding activity and delay virus reproduction in flat cells.
  J. Virol., 67:5198-5205 (1993).   PubMed   Full Text
• Freimuth P. and Anderson C.W.,
  Human adenovirus serotype 12 virion precursors pMu and pVI are cleaved at amino-terminal and carboxy-terminal sites that conform to the adenovirus 2 endoproteinase cleavage consensus sequence.
  Virology, 193:348-355 (1993).   PubMed