Dr Brendan O Connor

Biography

2011-14 Head, School of Biotechnology.
2009  Invited speaker, 8th International Conference on Protein Stabilisation – ProStab2009, Apr 14-17, Graz, Austria.
2006-10 Deputy Head, School of Biotechnology.
2004 School Research Convenor (until 2008); Promoted Senior Lecturer (Dec).
1999-to date Member of National Centre for Sensor Research, DCU.
1997 Published 200-page sole-author Stabilizing Protein Function, Springer, Berlin ISBN 3 540 63189 5.
1990 Appointed to permanent academic position. 1987-90 Postdoc researcher, temporary lecturer, NIHED/ DCU.
1984-7 Noctech Ltd (later Cambridge Diagnostics), Galway: immunodiagnostics development.
1981-4 WBE Ltd (later InterBio), Dublin: microbial biomass product development and technical services.
1982 PhD, University of Dublin (Trinity College) for 1979-81 research on mammalian arylsulphatases (Biochemistry Dept.; 2 peer-reviewed papers, 1 conference paper).
1978 BA (Mod), H2.1, Biochemistry, University of Dublin (Trinity College).

Total Graduations and Publications: 9 PhD, 3 MSc Graduates.
>40 peer-reviewed papers, 8 refereed reviews (including 2 invited articles), 1 sole-author book, 10 book chapters, 2 patent applications, 8 conference/ other papers.

Research Expertise

PhD Students

  • PhD Student #1
  • PhD Student #2
  • PhD Student #3

Select Publications

Structural Behaviour and Gene Delivery in Complexes Formed Between DNA and Arginine-Containing Peptide Amphiphiles
  Silva ER, Cooney G, Hamley IW, Alves WA, Lee S, O'Connor BF, Reza M, Ruokolainen J, Walls D.      2016      Soft Matter
This article defines protein stability, emphasizes its importance and surveys some notable recent publications (2004–2008) in the field of protein stability/stabilization. Knowledge of the factors stabilizing proteins has emerged from denaturation studies and from study of thermophilic (and other extremophilic) proteins. One can enhance stability by protein engineering strategies, the judicious use of solutes and additives, immobilization, and chemical modification in solution. General protocols are set out on how to measure the kinetic thermal stability of a given protein and how to undertake chemical modification of a protein in solution.

We describe in depth the structure of complexes formed between DNA and two classes of arginine-containing peptide amphiphiles, namely, the lipopeptide PRW-C16 (P = proline, R = arginine, W = tryptophan, C16 = C16 : 0 alkyl chain) and the bolaamphiphile RFL4FR (R = arginine, F = phenylalanine, L = leucine). A combination of X-ray and neutron scattering provided unprecedented insights into the local structure of these complexes. Lipopeptide-based complexes self-assembled into layered structures with large-scale fractal features, hosting DNA in the interstices. Bola-amphiphile scaffolds were characterized by planar structures with DNA strands presumably sandwiched in-between peptide nanotapes. Importantly, complexation did not affect the structural integrity of DNA in either of the two complexes. The bolaamphiphile conjugates displayed high levels of molecular ordering in contrast to the liquid-crystalline features observed in lipopeptide assemblies. Peptide-DNA complexes were assessed for their potential as a means to deliver the reporter vector pEGFP-N1 into SW480 human colon carcinoma cells. Successfully transfected cells expressed green fluorescent protein. The potentiating effect of PRW-C16 on the cellular uptake of ectopic DNA was found to be much greater than that observed with RFL4FR. In contrast to the bolaamphiphile-based conjugate, the liquid-crystalline nature of the lipopeptide complex is likely to play a key role in DNA release and transfection efficiency since these weakly bound structures require lower energy expenditure during disassembly and load release.

 

Single Cell Level Glycan Profiling On The Microfluidic Lab-In-A-Trench Platform
  Damien King, Triona M. O'Connell, Chandra K Dixit, Brendan O'Connor, Dermot Walls, Jens Ducrée      2014      Conference Paper
Horseradish peroxidase (HRP) is a commonly used enzyme in many biotechnological fields. Improvement of HRP stability would further increase its potential application range. In the present study, 13 single- and three double-mutants of solvent exposed, proximal lysine and glutamic acid residues were analysed for enhanced H2O2 stability. Additionally, five single- and one pentuple-consensus mutants were investigated. Most mutants displayed little or no alteration in H2O2 stability; however, three (K232N, K241F and T110V) exhibited significantly increased H2O2 tolerances of 25- (T110V), 18- (K232N), and 12-fold (K241F). This improved stability may be due to an altered enzyme-H2O2 catalysis pathway or to removal of potentially oxidisable residues.

It is widely recognised that the earliest changes that occur when a cell is stressed or becoming diseased are altera-tions in its surface glycosylation. Current techniques for the glycoprofiling of the surfaces of single cells are either limited to the analysis of large populations or are unable to handle sequential probing. We report a novel approach for spatio-temporally resolved glycoprofiling of single live cells utilising the microfluidic Lab-in-a-Trench platform which performs the capture and retention of cells, along with shear-free reagent loading. This approach enables ex-haustive glycoprofiling and glycan mapping on the surface of individual live cells with multiple lectins.

 

Sequential Glycan Profiling at Single Cell Level with the Microfluidic Lab-in-a-Trench Platform
  Triona M. O'Connell, Damien King, Chandra K Dixit, Brendan O'Connor, Dermot Walls, Jens Ducrée      2014      Lab on a Chip

It is now widely recognised that the earliest changes that occur on a cell when it is stressed or becoming diseased are alterations in its surface glycosylation. Current state-of-the-art technologies in glycoanalysis include mass spectrometry, protein microarray formats, techniques in cytometry and more recently, glyco-quantitative polymerase chain reaction (Glyco-qPCR). Techniques for the glycoprofiling of the surfaces of single cells are either limited to the analysis of large cell populations or are unable to handle multiple and / or sequential probing. Here, we report a novel approach of single live cell glycoprofiling enabled by the microfluidic “Lab-in-a-Trench” (LiaT) platform for performing capture and retention of cells, along with shear-free reagent loading. The significant technical improvement on state-of-the-art is the demonstration of consecutive profiling of glycans on a single cell by sequential elution of the previous lectin probe using their corresponding free sugar. We have qualitatively analysed glycan density on the surface of individual cells. This has allowed us to qualitatively co-localise the observed glycans. This approach enables exhaustive glycoprofiling and glycan mapping on the surface of individual live cells with multiple lectins. The possibility of sequentially profiling glycans on cells will be a powerful new tool to add to current glycoanalytical techniques. The LiaT platform will enable cell biologists to perform many high sensitivity assays and also will also make a significant impact on biomarker research.

 

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