Staff Profile:Dr John Brazier

Name:

Dr John Brazier

Job Title:

Lecturer, Pharmaceutical Chemistry Room 2.19 Chemistry

Responsibilities:

Areas of Interest:

My main area of interest is the synthesis of modified nucleosides and their incorporation and study within helical structures. These modified nucleoside structures and related oligonucleotides are useful in investigating biological processes. The primary interest of my research is the investigation of an unusual four stranded DNA structure known as the i-motif. The i-motif is a four stranded structure formed by cytosine rich sequences and since the first report in 1993 has been investigated using several techniques. Central to the i-motif structure is the formation of cytosine-protonated cytosine base pairs forming parallel duplexes which then associate anti-parallel to one another through intercalation. Telomeres are found at the ends of all chromosomes and have been implicated in genome integrity and cellular aging. There is much research focussed on the G-rich strands of these telomeric sequences and the associated G-quadruplex structure formed, but research into the structures formed by the complementary C-rich strand is much more limited. In the last several years several proteins, including human proteins hnRNP K and PCBP1 have been found to recognise C-rich telomeric sequences. Recent studies have shown that PCBP1 is present in the human telomere/telomerase complex and specific binding of a C-rich sequence in the promoter of the human c-myc gene, by hnRNP K can activate transcription. Many of these studies have used conditions favourable for i-motif formation but there is no evidence for recognition of the i-motif structure itself. The aim of my research is the formation of a fixed i-motif structure, through chemical modification of the DNA structure and to investigate the protein binding capabilities of these fixed structures.

Another research interest is targetting of long sequences of DNA. Trinucleotide repeat disorders (such as Huntington’s disease and myotonic dystrophy) are caused by abnormally extended regions of triplet repeats, numbering in the 1000’s in patients compared to 10’s under normal circumstances. These regions of repeats are an interesting target for both treatment and diagnosis, but current technologies such as antisense and antigene therapies are not suitable for such long sequences of DNA. Our approach is to use minor groove binders to form extended networks along the DNA sequences. Initial research conducted at Kyushu University, Japan, focussed on the use of metal ions to assemble binding ligand along a DNA template, but recent results suggest that the metal ions may not be needed, as ligand-ligand interactions may lead to co-operative binding. We hope to work with the researchers in Japan to investigate allosteric binding of minor groove binders to DNA mediated by weak intermolecular forces.

Research groups / Centres:

Publications:

1. J.A. Brazier, I. Onishi, S. Sasaki, Binding of two bis-bipyridine minor groove binders to a DNA template in the presence of Cu²⁺ ions, Nucleic Acids Symp. Ser. (Oxf)., 2008, (52), 107.
2. Joanne Bently, John A. Brazier, Julie Fisher, Richard Cosstick, Duplex stability of DNA•DNA and DNA•RNA duplexes containing 3’-S-phosphorothiolate linkages, Org. Biomol. Chem., 2007, 5, 3698.
3. H.K. Jayakumar, J.L. Buckingham, J.A. Brazier, N.G. Berry, R. Cosstick, and J. Fisher, NMR studies of the conformational effect of single and double 3'-S-phosphorothiolate substitutions within deoxythymidine trinucleotides, Magnetic Resonance in Chemistry, 2007, 45, 340.
4. Buckingham J, Brazier JA, Fisher J and Cosstick R, Incorporation of a S-glycosidic linkage into a glyconucleoside changes the conformational preference of both furanose sugars, Carbohydrate Research, 2007, 342 (1), 16.
5. Shibata, T.; Buurma, N. J.; Brazier, J. A.; Thompson, P.; Haq, I.; Williams, D. M., 7,8-dihydropyrido[2,3-d]pyrimidin-2-one; a bicyclic cytosine analogue capable of enhanced stabilisation of DNA duplexes, Chemical Communications, 2006, 33, 3516.
6. John A. Brazier, Julie Fisher, Richard Cosstick, Stabilistaion of the DNA I-motif by Incorporation of 3’-S-Phosphorothiolate Linkages, Angewandte Chemie International Edition, 2006, 45, (1), 114-117.
7. John A. Brazier, Julie Fisher, Richard Cosstick, 3'-S-Phosphorothiolate Linkages Within Multistranded Helical Structures, Collection Symposium Series (M. Hocek, Ed.), 2005, 7, 351-354.
8. Joanne Buckingham, Ghalia Sabbagh, John Brazier, Julie Fisher, Richard Cosstick, Control of DNA Conformation Using 3'-S-Phosphorothiolate-Modified Linkages, Nucleosides, Nucleotides and Nucleic Acids, 2005, 24, 491-495.
9. Sarah L. Elliott, John Brazier, Richard Cosstick, Bernard A. Connolly, Mechanism of the E. coli DNA T:G-mismatch endonuclease (Vsr protein) probed with thiophosphate-containing oligodeoxynucleotides, Journal of Molecular Biology, 2005, 353, (3), 692-703.
10. John A. Brazier, Takayuki Shibata, John Townsley, Brian F. Taylor, Elaine Frary, Nicholas H. Williams, David M. Williams, Amino-functionalized DNA: the properties of C5-amino-alkyl substituted 2’-deoxyuridines and their application in DNA triplex formation, Nucleic Acids Research, 2005, 33, (4), 1362-1371.
11. John A. Brazier, David M. Williams, Synthesis and applications of C5-amino modified 2’-deoxyuridines, Collection Symposium Series (Z. Toèík and M. Hocek, Eds.), 2002, 5, 221-224.
12. Lee, S. E.; Sidorov, A.; Gourlain, T.; Mignet, N.; Thorpe, S. J.; Brazier, J. A.; Dickman, M. J.; Hornby, D. P.; Grasby, J. A.; Williams, D. M., Enhancing the catalytic repertoire of nucleic acids: a systematic study of linker length and rigidity, Nucleic Acids Research, 2001 29, (7), 1565-1573.