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In 1993 Jon isolated a novel, membrane-bound protein 'supercomplex' of photosystem II (PSII) from higher plants. During his Ph.D. studies ('93-'97) he fully characterised this supercomplex biochemically with 14 different techniques and found that this macromolecular assembly retained bound components of the light harvesting complex (Lhcb1, 2, 4 and 5) in addition to the soluble oxygen-evolution enhancing extrinsic polypeptides (PsbO, PsbQ and PsbP). This work was first revealed structurally in a co-authored paper (PNAS 1995), and further investigations and co-authored publications probed such complexes from cyanobacteria and green algae. For his first post-doctoral position ('97-99), he wished to visualise these protein assemblies in 3D and chose to use cryo- and negative stain electron microscopy (EM) with single particle image processing techniques. For his second post-doc. he tackled issues of sample hetereogeneity through the application of computer CPU-intensive classification procedures. To date this has yielded many 3D structures at resolutions of up to 1.7 nm for higher plants and 2.5 nm for green algae and cyanobacteria. Jon has co-authored a review outlining these techniques: Prog. Mol. Biol. Biophys. (2001) 75, 121-164.
Jon currently holds a Royal Society University Research Fellowship position, with the goals to visulaise medium resolution macro-molecular protein frameworks, primarily for the investigation of photosynthetic structure / function relationships, extended to 2009. This was recently transferred to The School of Biological and Chemical Sciences where he will continue in a tenured position after this date. He has published over 35 refereed articles relating to the above interests, as well as those in X-ray crystallography (J. Struct. Biol. 2003) and protein folding prediction using internet-based databases and alignment tools (J. Biol. Chem. 2002).
In one of these investigations, a discovery was made with Thomas Bibby and James Barber at Imperial College, where an 18-subunit ring of a photosystem II PsbC-like protein was observed to surround the trimeric core of Photosystem I, in an iron-stressed cyanobacterium Synechocystis PCC6803 (Nature Aug. 2001). This was followed by a second observation of such a ring, this time of 'Pcb' proteins surrounding a PSI trimer in the green oxyphotobacterium Prochlorococcus (Nature Oct. 2001). Furthermore, these PsbC-like proteins were shown to be expressed around both PSI and PSII, in Prochlorococcus (Nature 2003) and Prochloron (PNAS 2003), in collaboration locally & with French/Australian groups, respectively. 3D structures for a LHCI-PSI supercomplex from the green alga, Chlamydomonas reinhardtii, (J. Biol. Chem. 2003; cited in Stryer / Lehninger textbooks; 2007) including supercomplexes fixed in different functional states (FEBS J 2005), phage shock protein (PspA; J. Biol. Chem. 2004), refinement of the LHCII-PSII plant supercomplex model (BBA Bioenergetics 2006), investigating protease activity (J. Biol. Chem., 2006), insectotoxin (Toxicon, 2007) and atomic force microscopy on photosynthetic membranes (Biochemistry, 2008) are other highlights. The highly challenging arena of PSI assembly intermediates has been probed most recently (2009) in collaboration with Japanese, German and Swiss groups (The Plant Cell 2009).
Jon has taught UG classes (Molecular Photobioenergetics/Calvin CycleLectures; 120 students), M.Sc. and Undergraduate projects (12 in total), as well as providing image processing/ EM guidance for 5 Ph.D projects. He has set and marked UG exam questions, and been an examiner for UG final year projects. Two BSc students have been hosted per year via Imperial College's Undergraduate Research Opportunities Program (UROP; www.urop.ic.ac.uk). Jon constantly referees publications with several journals for the scientific community and is currently an Associate Editor of Photochemical & Photobiological Sciences (www.rsc.org/pps). He has been, concurrently, Staff Representative on Faculty and GM-safety committees, and organised a Divisional seminar series (26 lectures in 18 months). He currently sits on a Departmental IT provision committee.
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