Prof. J.H.P. Bayley

Chemical Research Laboratory

Email Address: hagan.bayley@chem.ox.ac.uk

Telephone: 44 (0) 1865 285 100 or 44 (0) 1865 285 101

Research Group Web Site

Some topics of current research in our include:

1. Engineering Membrane Channels and Pores
Pore-forming proteins are being engineered for applications in biotechnology. Our main focus is on a-hemolysin, a bacterial toxin that forms a heptameric transmembrane pore of known three-dimensional structure. By using genetic engineering and targeted chemical modification, pores are being made with diverse functional properties. In addition, transmembrane b barrels are being engineered by combining fragments from various bacterial toxins and porins, as well as polypeptide segments designed de novo. The new molecules are finding applications in several areas including drug delivery and the construction of biosensors. These efforts require an excellent basic understanding of membrane protein assembly and function, and we are continuing our work in this area, in particular by using single molecule approaches.

2. High-Throughput Screening with Membrane Proteins
Recent advances have demonstrated that large fractions of prokaryotic and eukaryotic genomes encode membrane proteins. Therefore, there is a pressing need for high-throughput methods to investigate the assembly and functional properties of these polypeptides. By collaborating with laboratories conversant with chip technology, we are developing approaches for the parallel processing of hundreds of membrane samples. Eventually, the approach will yield procedures for refolding membrane proteins and for forming three-dimensional crystals from them. If functional membrane proteins can be obtained on chips, they will be used for high-throughput assays in drug discovery and as a basis for making biosensor arrays. 

3. Biomolecular Materials by Design
The design and synthesis of biomolecular materials is a rapidly growing interdisciplinary area, in which the properties of molecules found in nature are mimicked or extended to produce materials with unusual properties. An additional goal is to manufacture and dispose of materials by environmentally benign methods of low energy cost. The heterologous expression of protein-based materials is an attractive option. We are exploring this and related approaches for making materials that form porous sheets, fibers, adhesives and elastomers. For example, we have initiated engineering studies on S layers, the robust porous proteinaceous envelopes that surround many bacterial cells. One goal is to obtain porous monolayers containing molecular switches, for use in biosensors. In another example, we are engineering abductin, a protein found in the highly elastomeric inner hinge ligaments of bivalve mollusks. The project will yield elastomers for use thin films, and in microfluidic and energy storage devices.

4. Caged Peptides and Proteins for Signal Transduction Research
The use of "caged" reagents allows the photogeneration of molecules on or in cells with precise spatial and temporal control. In signal transduction research, effectors and inhibitors can be released at known sites, in defined doses, and at predetermined times. We are using a variety of photoremovable protecting groups to cage peptides and proteins for studies of cell signaling. One tactic has been to derivatize proteins engineered to contain single cysteines at key positions. In this way, a photoactivatable catalytic subunit of protein kinase A has been made. The activities of many cell signaling proteins are modulated by phosphorylation. Therefore, we are also examining peptides and proteins modified on the sulfur atom of thiophosphoryl groups.

Selected Recent Publications

1. "Stochastic sensing of organic analytes by a pore-forming protein containing a molecular adapter", L. Gu, O. Braha, S. Conlan, S. Cheley, H. Bayley, Nature 398, 686-690 (1999)
   
   
2. "Intracellular trehalose improves the survival of cryopreserved mammalian cells", A. Eroglu, M.J. Russo, R. Bieganski, A. Fowler, S. Cheley, H. Bayley, M. Toner, Nature Biotechnol. 18, 163-167 (2000)
   
   
3. "A protein pore with a single polymer chain tethered within the lumen", S. Howorka, L. Movileanu, X. Lu, M. Magnon, S. Cheley, O. Braha, H. Bayley, J. Am. Chem. Soc. 122, 2411-2416 (2000)
   
   
4. "Reversal of charge selectivity in transmembrane protein pores by using non-covalent molecular adaptors", L. Gu, M. Dalla Serra, J.B. Vincent, G. Vigh, S. Cheley, O. Braha, H. Bayley, Proc. Natl. Acad. Sci. USA 97, 3959-3964 (2000)
   
   
5. "Simultaneous stochastic sensing of divalent metal ions", O. Braha, L. Gu, L. Zhou, X. Lu, S. Cheley, H. Bayley, Nature Biotechnol. 18, 1005-1007 (2000)
   
   
6. "Biochemical and biophysical characterization of OmpG: A monomeric porin", S. Conlan, Z. Yong, S. Cheley, H. Bayley, Biochemistry 39, 11845-11854 (2000)
   
   
7. "Detecting protein analytes that modulate transmembrane movement of a polymer chain within a single protein pore", L. Movileanu, S. Howorka, O. Braha, H. Bayley, Nature Biotechnol. 18, 1091-1095 (2000)
   
   
8. "Surface-accessible residues in the monomeric and assembled forms of a bacterial surface layer protein", S. Howorka, M. Sara, Y. Wang, B. Kuen, U.B. Sleytr, W. Lubitz, H. Bayley, J. Biol. Chem. 275, 37876-37886 (2000)
   
   
9. "Capture of a single molecule in a nanocavity", L. Gu, S. Cheley, H. Bayley, Science 291, 636-640 (2001)
   
   
10. "The staphococcal leukocidin bicomponent toxin forms large ionic channels", G. Miles, S. Cheley, O. Braha, H. Bayley, Biochemistry 40, 8514-8522 (2001)
    
    
11. "Partitioning of a polymer into a nanoscopic protein pore obeys a simple scaling law", L. Movileanu, H. Bayley, Proc. Natl. Acad. Sci. 98, 10137-10141 (2001)
    
    
12. "Prolonged residence time of a noncovalent molecular adapter, b-cybclodextrin, within the lumen of mutant a-hemolysin pores", L. Gu, S. Cheley, H. Bayley, J. General Physiol. 118, 481-494 (2001)
    
    
13. "Beneficial effect of intracellular trehalose on the membrane integrity of dried mammalian cells", T. Chen, J. Acker, A. Eroglu, S. Cheley, H. Bayley, A. Fowler, M. Toner, Cyrobiology 43, 168-181 (2001)
    
    
14. "Subunit composition of a bicomponent toxin: Staphylococcal leukocidin forms an octameric transmembrane pore", G. Miles, L. Movileanu, H. Bayley, Protein Sci. 11, 894-902 (2002)
    
    
15. "Catalytic subunit of protein kinase A caged at the activating phosphothreonine", K. Zou, S. Cheley, R.S. Givens, H. Bayley, J. Am. Chem. Soc. 124, 8220-8229 (2002)
    
    
16. "Stochastic sensing of nanomolar inositol 1,4,5-trisphosphate with an engineered pore", S. Cheley, L. Gu, H. Bayley, Chem. Biol. 9, 829-838 (2002)
    
    
17. "Kinetics of a reversible covalent-bond-forming reaction observed at the single-molecule level", S.-H. Shin, T. Luchian, S. Cheley, O. Braha, H. Bayley, Angew. Chem. Int. Ed. 31, 3707-3709 (2002)
    
    
18. "Survival of desiccated mammalian cells: beneficial effects of isotonic media", J.P. Acker, A. Fowler, B. Lauman, S. Cheley, M. Toner, Cell Preserv. Technol. 1, 129-140 (2002)
    
    
19. "Probing distance and electrical potential within a protein pore with tethered DNA", S. Howorka, H. Bayley, Biophysical J. 83, 3202-3210 (2002)
    
    
20. "Measurement of trehalose loading of mammalian cells with a metal-actuated switchable pore", J.P. Acker, X. Lu, V. Young, S. Cheley, H. Bayley, A. Fowler, M. Toner, Biotechnol. Bioeng. 82(5), 525-532 (2003)
    
    
21. "Kinetics of a three-step reaction observed at the single-molecule level", T. Luchian, S.-H. Shin, H. Bayley, Angew. Chem. Int. Ed. 42, 1925-1929 (2003)
    
    
22. "Partitioning of individual flexible polymers into a nanoscopic protein pore", L. Molvileanu, S. Cheley, H. Bayley, Biophys. J. 85, 897-910 (2003)
    
    
23. "Single-molecule covalent chemistry with spatially separated reactants", T. Luchian, S.-H. Shin, H. Bayley, Angew. Chem. Int. Ed. 42, 3766-3771 (2003)
    
    
24. "Folding of a monomeric porin, OmpG, in detergent solution", S. Conlan, H. Bayley, Biochemistry 42, 9453-9465 (2003)
    
    
25. "Electroosmotic enhancement of the binding of a neutral molecule to a transmembrane pore", L.Q. Gu, S. Cheley, H. Bayley, Proc. Natl. Acad. Sci. USA 100, 15498-15503 (2003)
    
    
26. "Stochastic detection of monovalent and bivalent protein-ligand interactions", S. Howorka, J. Nam, H. Bayley, D. Kahne, Angew. Chem. Int. Ed. 43, 842-846 (2004)