Biography

orban


CONTACT INFORMATION

 Office Phone: 240-314-6221
 Office Address: 0130
 Email: jorban@umd.edu
 Group Website

Professor

Education

  • B. Sc. (Honors, 1st class) University of Adelaide, Adelaide, Australia (Chemistry).
  • Ph.D. Australian National University, Canberra (Chemistry).
  • CSIRO Postdoctoral Fellow, 1985-1987.

Research Interests

High field biomolecular NMR spectroscopy; protein structure, folding, and design; metamorphic proteins; protein-protein interactions; allostery; intrinsically disordered proteins.

Professional Experience

1980-1981 Honors Student and Teaching Assistant, Dept. of Organic Chemistry, Univ. of Adelaide.
1981-1985 Graduate Student and Teaching Assistant, Research School of Chemistry, Australian National University.
1985-1987 CSIRO Postdoctoral Fellow, Dept. of Chemistry, McMaster University (Canada).
1987-1990 Postdoctoral Research Associate, Dept. of Chemistry, U. Washington, Seattle.
1991-1997 Assistant Professor, Center for Advanced Research in Biotechnology (CARB), University of Maryland Biotechnology Institute (UMBI).
1997-2006 Associate Professor, CARB, UMBI.
2006-2010 Professor, CARB, UMBI.
4/2010-present Professor, Dept. of Chemistry and Biochemistry, University of Maryland College Park.
4/2010-present Professor, IBBR, University of Maryland College Park.

Honors

1981-1985 Australian Commonwealth Postgraduate Research Fellowship.
1985-1987 CSIRO-Australia Postdoctoral Fellowship.

Selected Publications

  1. Alexander, P. A., He, Y., Chen, Y., Orban, J., and Bryan, P. N. (2007) The design and characterization of two proteins with 88% sequence identity but different structure and function. Proc. Natl. Acad. Sci. USA 104, 11963-11968.
  2. He, Y., Chen, Y., Alexander, P., Bryan, P. N., and Orban, J. (2008) NMR structures of two designed proteins with high sequence identity but different fold and function. Proc. Natl. Acad. Sci. USA 105, 14412-14417.
  3. Alexander, P., He, Y., Chen, Y., Orban, J., and Bryan, P. N. (2009) A minimal sequence code for switching protein structure and function. Proc. Natl. Acad. Sci. USA 106, 21149-54.
  4. Shen, Y., Bryan, P. N., He, Y., Orban, J., Baker, D., and Bax, A. (2010) De novo structure generation using chemical shifts for proteins with high sequence identity but different folds. Protein Science 19, 349-356.
  5. Bryan, P. N. and Orban, J. (2010) Proteins that switch folds. Curr. Opin. Struct. Biol. 20, 482-488.
  6.  Zeng, Y., He, Y., Yang, F., Getzenberg, R., Orban, J., and Kulkarni, P. (2011) The cancer/testis antigen prostate-associated gene 4 (PAGE4) is a highly intrinsically disordered protein. J. Biol. Chem. 286, 13985-13994. [PMCID: PMC3077599]
  7. He, Y., Chen, Y., Alexander, P. A., Bryan, P. N., and Orban, J. (2012) Mutational tipping points for switching protein folds and functions. Structure 20, 283-291. [PMCID: PMC3278708]
  8. He, Y., Chen, Y., Oganesyan, N., Ruan, B., O’Brochta, D., Bryan, P. N., and Orban, J. (2012) Solution NMR structure of a sheddase inhibitor prodomain from the malarial parasite Plasmodium falciparum. Proteins 80, 2810-2817. [PMID: 23011838]
  9. Bryan, P. N. and Orban, J. (2013) Implications of protein fold switching. Curr. Opin. Struct. Biol. 23, 314-316.
  10. He, Y., Rangarajan, S., Kerzic, M., Luo, M., Chen, Y., Wang, Q., Yin, Y., Workman, C. J., Vignali, K. M., Vignali, D. A. A., Mariuzza, R. A., and Orban, J. (2015) Identification of the docking site for CD3 on the T cell receptor eta chain by solution NMR. J. Biol. Chem. 290, 19796-19805 [PMCID: PMC4528140]
  11. Porter, L. L., He, Y., Chen, Y., Orban, J., and Bryan, P. N. (2015) Subdomain interactions foster the design of two protein pairs with ~80% sequence identity but different folds. Biophys. J. 108, 154-162. [PMCID: PMC4286614]
  12. He, Y., Chen, Y., Mooney, S. M., Rajagopalan, K., Bhargava, A., Sacho, E., Weninger, K., Bryan, P. N., Kulkarni, P., and Orban, J. (2015) Phosphorylation-induced conformational ensemble switching in an intrinsically disordered cancer/testis antigen. J. Biol. Chem. 290, 25090-25102. [PMCID: PMC4599013]
  13. Kulkarni, P., Dunker, A. K., Weninger, K., and Orban, J. (2016) Prostate-associated gene 4 (PAGE4), an intrinsically disordered cancer/testis antigen, is a novel therapeutic target for prostate cancer. Asian J. Androl. 18, 695-703. [PMCID: PMC5000790]
  14. Kulkarni, P., Jolly, M. K., Jia, D., Mooney, S. M., Bhargava, A., Kagohara, L. T., Chen, Y., Hao, P., He, Y., Veltri, R., Grishaev, A., Weninger, K., Levine, H., and Orban, J. (2017) Phosphorylation-induced conformational dynamics in an intrinsically disordered protein and potential role in phenotypic heterogeneity. Proc. Natl. Acad. Sci. USA 114, E2644-E2653. [PMCID: PMC5380051]
  15. Lin, X.,Roy, S.,Jolly, M. K.,Bocci, F.,Schafer, N. P.,et al. (2018) PAGE4 and Conformational Switching: Insights from Molecular Dynamics Simulations and Implications for Prostate Cancer. J. Mol. Biol. S0022-2836, 30406.
  16. Jolly, M. K.,Kulkarni, P.,Weninger, K.,Orban, J.,Levine, H. (2018) Phenotypic Plasticity, Bet-Hedging, and Androgen Independence in Prostate Cancer: Role of Non-Genetic Heterogeneity. Front. Oncol. 8, 50.
  17. Kulkarni, P., Solomon, T., He, Y., Chen, Y., Bryan, P. N., and Orban, J. (2018) Structural metamorphism and polymorphism in proteins on the brink of thermodynamic stability. Protein Science 27, in press.
  18. Salgia, R., Jolly, M. K., Dorff, T., Lau, C., et al. (2018) Prostate associated gene 4 (PAGE4): Leveraging the conformational dynamics of a dancing protein cloud as a therapeutic target. J. Clin. Med. 7, 156.

Research

My research interests are focused in the area of protein structural biology and design, particularly in understanding how the malleability of protein folds relates to biological function. High field solution NMR spectroscopy and other biophysical and biochemical methods are employed in my laboratory.

Protein fold switching and metamorphism

While most globular proteins populate relatively homogeneous conformational ensembles under physiological conditions, significant exceptions continue to emerge. Many biological processes involve extensive re-modeling of protein conformation, including switches from disordered to ordered states. Some natural proteins can even undergo large-scale transitions from one ordered state to another involving major shifts in secondary structure, repacking of the protein core, and exposure of new surfaces.

Such “metamorphic” proteins are capable of performing alternative functions triggered by binding interactions that stabilize latent conformational states. The ability of these proteins to completely change their fold topologies has implications in a number of important areas including computational and structural biology, protein evolution, human disease, and protein design. We are working on biophysical characterization of protein switches between a number of common fold topologies that occur through short mutational paths or in response to external stimuli. (See Proc. Natl. Acad. Sci. USA 2007, 104, 11963; 2008, 105, 14412; 2009, 106, 21149. Curr. Opin. Struct. Biol. 2010, 20, 482; 2013, 23, 314. Structure 2012, 20, 283. Biophys. J. 2015, 108, 154).


Intrinsically disordered proteins (IDPs)

The proteins described above are typically on the margin of stability and can be tipped toward one fold or another through relatively subtle changes in sequence or environmental triggers. Intrinsically disordered proteins on the other hand have no stable 3D structure and their flexibility allows them to adopt many different conformations. Thus, their structures are characterized by conformational ensembles that are typically non-random coil. These conformational ensembles can be shifted, sometimes dramatically, in response to post-translational modifications or ligand binding. Conceptually, they are similar to metamorphic proteins, having the ability to adopt different structures with different binding partners for example. We are studying an IDP called prostate associated gene 4 (PAGE4) that plays an important role in prostate cancer using a range of biophysical tools including NMR and small angle X-ray scattering (SAXS). PAGE4 undergoes large changes in its conformational ensemble and cellular function depending on the level of phosphorylation. (See J. Biol. Chem. 2011, 286, 13985; 2015, 290, 25090. Proc. Natl. Acad. Sci. USA 2017, 114, E2644).

Multi-protein signaling complexes / allostery

The conformational changes described above are large amplitude. However, small structural changes can also play an important role in key biological processes. An example of this is the interaction between peptide-MHC and T cell receptor (TCR) molecules. Although the 3D structures of pMHC, TCR, and pMHC-TCR are known, how this non-covalent binding interaction transmits information to distal TCR-associated CD3 molecules and triggers T cell signaling remains a mystery. We are working on characterizing the binding interaction between TCR and CD3 molecules and also understanding how pMHC-binding to TCR leads to allosteric changes that affect the TCR-CD3 interaction. (See J. Biol. Chem. 2015, 290, 19796).

Print Friendly