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Dr Arwen Pearson

Dr Pearson is a RCUK Academic Research Fellow in Protein Structure, Modelling and Design in the Institute for Molecular and Cellular Biology. She obtained her B.Sc. in Biochemistry from the University of Bath in 1997 and her Ph.D. in structural biology from the University of St Andrews in 2001. She joined the University of Leeds in 2006 after postdoctoral training in structural enzymology with Dr. Carrie Wilmot at The University of Minnesota, USA.

Research Areas: Structural Enzymology and Single Crystal Spectroscopy

Research

4DX XSpectra
single crystal
spectrometer
(www.4dx.se)

I use a combination of single-crystal spectroscopy and X-ray crystallography to probe enzyme mechanism. Many enzymes retain their catalytic activity when crystalline and single crystal spectroscopy allows me to follow the enzyme catalysed reaction occurring within the crystal. I then use rapid freeze trapping techniques to arrest the reaction at a spectroscopically defined intermediate for X-ray structure determination. Being able to directly visualise the sequence of events occurring during catalysis gives us incredible insight into how enzymes are able to be such efficient catalysis. In addition, it provides detailed information useful in designing mechanism based specific inhibitors or predicting mutations that would improve efficiency or alter substrate specificity. This kind of information is important both in the development of new pharmaceuticals and in the generation of new enzyme based green catalysts in biotechnology.

Obviously, when probing enzyme mechanism it is extremely important to know that the X-ray structure obtained from a crystal is that of the desired intermediate. Single crystal spectroscopy is also used as an important quality control tool in X-ray crystallography. Often X-rays can induce changes in the protein during X-ray diffraction data collection. These can include very subtle changes, such as alterations in the redox state of cofactors or larger more noticeable changes that include decarboxylations and disulphide bond breakage. While these larger changes are usually visible in the resulting electron density maps, the more subtle redox-based changes are often only detectable by single crystal spectroscopy.

Current Research Projects:

Human molybdopterin enzymes

The human molybdopterin containing enzyme xanthine oxidoreductase (XOR) is an exciting protein able to catalyse a variety of different reactions. This has led to its implication in numerous physiological and pathophysiological processes, including purine catabolism, NO generation in the cardiovascular system and superoxide generation in milk, proposed to help protect the newborn gut from bacterial infections. XOR can also reversibly switch between two kinetically distinguishable isoforms, a dehydrogenase and an oxidase which differ in their choice of oxidising substrate. I am interested in understanding how XOR can catalyse such a wide range of different reactions as well as how the switch between the two isoforms occurs and is regulated.

Publications from the last 5 years:

2009

Foster, TL; Tedbury, PR; Pearson, AR; Harris, M (2009) A comparative analysis of the fluorescence properties of the wild-type and active site mutants of the hepatitis C virus autoprotease NS2-3.. Biochim Biophys Acta /Pages, Pages

Owen, RL; Pearson, AR; Meents, A; Boehler, P; Thominet, V; Schulze-Briese, C (2009) A new on-axis multimode spectrometer for the macromolecular crystallography beamlines of the Swiss Light Source. J Synchrotron Radiat 16, 173-182

Kocabas, DS; Pearson, AR; Phillips, SEV; Bakir, U; Ogel, ZB; McPherson, MJ; Trinh, CH (2009) Crystallization and preliminary X-ray analysis of a bifunctional catalase-phenol oxidase from Scytalidium thermophilum. Acta Crystallogr F 65, 486-488

Campeotto, I; Carr, SB; Trinh, CH; Nelson, AS; Berry, A; Phillips, SEV; Pearson, AR (2009) Structure of an Escherichia coli N-acetyl-D-neuraminic acid lyase mutant, E192N, in complex with pyruvate at 1.45 angstrom resolution. Acta Crystallogr F 65, 1088-1090

2008

Pirrat, P; Smith, MA; Pearson, AR; McPherson, MJ; Phillips, SE (2008) Structure of a xenon derivative of Escherichia coli copper amine oxidase: confirmation of the proposed oxygen-entry pathway.. Acta Crystallogr Sect F Struct Biol Cryst Commun 64(Pt 12), 1105-1109

2007

Johnson, BJ; Cohen, J; Welford, RW; Pearson, AR; Schulten, K; Klinman, JP; Wilmot, CM (2007) Exploring molecular oxygen pathways in Hansenula polymorpha copper-containing amine oxidase. Journal of Biological Chemistry 282(24), 17767-17776

Pearson, AR; Elmore, BO; Yang, C; Ferrara, JD; Hooper, AB; Wilmot, CM (2007) The crystal structure of cytochrome P460 of Nitrosomonas europaea reveals a novel cytochrome fold and heme-protein cross-link. Biochemistry 46(28), 8340-8349

Pearson, AR; Pahl, R; Kovaleva, EG; Davidson, VL; Wilmot, CM (2007) Tracking X-ray derived redox changes in crystals of a methylamine dehydrogenase/amicyanin complex using single crystal UV/Vis microspectrophotometry. Journal of Synchrotron Radiation 14, 92-98

2006

Elmore, BO; Pearson, AR; Wilmot, CM; Hooper, AB (2006) Expression, purification, crystallization and preliminary X-ray diffraction of a novel Nitrosomonas europaea cytochrome, cytochrome P460. Acta Crystallographica. Section F, Structural Biology And Crystallization Communications 62, 395-398

Pearson, AR; Marimanikkuppam, S; Li, X; Davidson, VL; Wilmot, CM (2006) Isotope Labeling Studies Reveal the Order of Oxygen Incorporation into the Tryptophan Tryptophylquinone Cofactor of Methylamine Dehydrogenase. Journal of the American Chemical Society 128(38), 12416-12417

Li, X; Jones, LH; Pearson, AR; Wilmot, CM; Davidson, VL (2006) Mechanistic Possibilities in MauG-Dependent Tryptophan Tryptophylquinone Biosynthesis. Biochemistry 45, 13276-13283

2005

Jones, LH; Pearson, AR; Tang, Y; Wilmot, CM; Davidson, VL (2005) Active Site Aspartate Residues Are Critical for Tryptophan Tryptophylquinone Biogenesis in Methylamine Dehydrogenase. Journal of Biological Chemistry 280(17), 17392-17396

Wang, Y; Li, X; Jones, LH; Pearson, AR; Wilmot, CM; Davidson, VL (2005) MauG-dependent in vitro biosyntheisis of tryptophan tryptophylquinone in methylamine dehydrogenase.. Journal of the American Chemical Society 127, 8258-8259

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