Grzegorz Bulaj

Assistant Professor of Medicinal Chemistry

M.Sc. University of Wroclaw, Poland

Ph.D. University of Wroclaw, Poland

Research

My research is focused on discovering and engineering neuroactive peptides as potential therapeutics for pain and epilepsy. My current projects include: (1) engineering anticonvulsant neuropeptides to improve their properties as drugs, (2) discovery and chemical modification of subtype selective sodium channel peptide antagonists produced by cone snails, conotoxins, and (3) engineering of conotoxins to modify bioavailability. An underlying theme in all three projects is that the neurotoxins and endogenous neuropeptides being investigated target ion channels and receptors with high potency and selectivity, thus they possess some unique characteristics desirable for a design of safe therapeutics. If their stability and bioavailability could be improved, a systematic exploration of their potential as drugs for many neurological disorders would be more feasible. The chemical modifications currently being developed will be used to specifically engineer peptides with potential antinociceptive and antiepileptic activity. Thus, our long-term goal is to develop a technology platform that would facilitate the transformation of neuroactive peptides into drugs.

Recently, we discovered a new group of conotoxins that exhibit the novel pharmacological properties of blocking sodium channels (see Figure 1). These short, disulfide-crosslinked neurotoxins indeed exhibit analgesic activity in neuropathic pain models and may also provide a new class of pharmacological tools for sodium channels. Current work includes defining structural determinants of their selectivity profiles for various sodium channel subtypes and engineering bioavailability through backbone modifications. This part of the project is a collaborative effort with several groups specialized in biology, electrophysiology and molecular biology of sodium channels (Professors Baldomero M Olivera and Doju Yoshikami from the U of U, Prof. Heinz Terlau from University of Lubeck). In collaboration with Professors Raymond S. Norton and Brian J. Smith from Melbourne, we also study structural properties of conotoxins, including backbone dynamics by means of NMR spectroscopy and molecular dynamics simulations.

My interests are also directed toward studying mechanisms of the oxidative folding of conotoxins. Conotoxins are peptide-based neurotoxins produced by predatory marine cone snails. This group comprises an estimated 100,000 unique amino acid sequences; almost all are rich in cysteine residues. Conotoxins possess ideal characteristics to study in vivo and in vitro folding mechanisms, since they are amenable to both chemical synthesis and recombinant expression. Questions that we address are: (1) how folding catalysts, molecular chaperones and other factors may affect oxidative folding of conotoxins, (2) what are mechanistic differences between in vivo and in vitro folding of conotoxins?

Bulaj Figure

Model structures of conotoxins targeting sodium channels.

References

1. Zhang L, Lee H, Pruess T, White HS, Bulaj G (2009) Synthesis and Applications of Polyamine Amino Acid Residues: Improving the Bioactivity of an Analgesic Neuropeptide, Neurotensin. J Med Chem 52:1514-7

2. Lee H, Zhang L, Smith MD, White HS, Bulaj G (2009) Glycosylated Neurotensin Analogs Exhibit the Subpicomolar Anticonvulsant Potency in the Pharmacoresistant Model of Epilepsy. ChemMedChem 4:400-405

3. Zhang L, Robertson CR, Green BR, Pruess T, White HS, Bulaj G (2009) Structural Requirements for a Lipoamino Acid in Modulating the Anticonvulsant Activities of the Systemically-Active Galanin Analogs. J Med Chem 52:1310-16

4. Bulaj G, Green BR, Lee HK, Robertson CR, White K, Zhang L, Sochanska M, Flynn SP, Adkins Scholl E, Pruess TH, Smith MD, White HS (2008) Design, Synthesis and Characterization of High-Affinity, Systemically-Active Galanin Analogs with Potent Anticonvulsant Activities. J Med Chem 51:8038-47

5. Walewska A, Zhang MM, Skalicky JJ, Yoshikami D, Olivera BM, Bulaj G (2009) Integrated Oxidative Folding of Cysteine/Selenocysteine-Containing Peptides: Improving Chemical Synthesis of Conotoxins. Angewandte Chemie Int Ed Engl 48:2221-4

6. Walewska A, Skalicky JJ, Davis DR, Zhang MM, Lopez-Vera E, Watkins W, Han TS, Yoshikami D, Olivera BM, Bulaj G (2008) NMR-Based Mapping of Disulfide Bridges in Cysteine-Rich Peptides: Application to the μ-Conotoxin SxIIIA. J Am Chem Soc 130:14280-86

7. Bulaj G (2008) Integrating the discovery pipeline for novel compounds targeting ion channels. Curr Opin Chem Biol 12:441-447

8. Lopez-Vera E, Walewska A, Skalicky JJ, Olivera BM, Bulaj G (2008) Role of Hydroxyprolines in the Oxidative Folding and Biological Activity of Conotoxins. Biochemistry 47:1741-1751

9. Zhang MM, Green BR, Catlin P, Fiedler B, Azam L, Chadwick A, Terlau H, McArthur JR, French RJ, Gulyas J, Rivier J, Smith BJ, Norton RS, Olivera BM, Yoshikami D, Bulaj G (2007) Structure/Function Characterization of μ-Conotoxin KIIIA, an Analgesic, Nearly Irreversible Blocker of a Neuronal Subtype of Mammalian Sodium Channels. J Biol Chem 282:30699-706

10. Green BR, Catlin P, Zhang MM, Fiedler B, Bayudan W, Morrison A, Norton RS, Smith BJ, Yoshikami D, Olivera BM, Bulaj G (2007) Conotoxins containing nonnatural backbone spacers: cladistic-based design, chemical synthesis, and improved analgesic activity. Chem Biol. 14:399-407

11. Buczek O, Green BR, Bulaj G (2007) Albumin is a redox-active crowding agent that promotes oxidative folding of cysteine-rich peptides. Biopolymers 88:8-19

12. Zhang MM, Fiedler B, Green BR, Catlin P, Watkins M, Garrett JE, Smith BJ, Yoshikami D, Olivera BM, Bulaj G (2006) Structural and Functional Diversity among mu-Conotoxins Targeting TTX-resistant Sodium Channels. Biochemistry 45:3723-32

13. Bulaj G, Zhang MM, Green BR, Fiedler B, Layer RL, Wei S, Nielsen JS, Low SJ, Klein BD, Wagstaff JD, Chicoine L, Harty TP, Terlau H, Yoshikami D, Olivera BM (2006) Synthetic muO-Conotoxin MrVIB Blocks TTX-Resistant Sodium Channel Nav1.8 and Has a Long-Lasting Analgesic Activity. Biochemistry 45:7404-14

14. Fuller E, Green BR, Catlin P, Buczek O, Nielsen JS, Olivera BM, Bulaj G (2005) Oxidative folding of conotoxins sharing an identical disulfide bridging framework. FEBS J. 272:1727-38

15. Buczek O, Olivera BM, Bulaj G (2004) Propeptide does not act as an intramolecular chaperone, but facilitates protein disulfide isomerase – assisted folding of a conotoxin precursor. Biochemistry 43:1093-1101

16. Bulaj G, Buczek O, Goodsell I, Jimenez EC, Kranski J, Nielsen JS, Garrett JE, Olivera BM (2003) Efficient oxidative folding of conotoxins and the radiation of venomous cone snails. Proc. Natl. Acad. Sci. USA 100:14562-68