Dr Stephen RobertsLecturer
My research expertise is the application of electrophysiological and molecular biological techniques to understand the regulation of ion transport across the biological membranes of plant and fungal cells. I currently use the filamentous fungus, Aspergillus nidulans and the yeast, Saccharomyces cerevisiae. My research interests have more recently focussed on anion efflux and Ca2+ influx across the plasma membrane of fungal cells towards identifying and evaluating potential new drug targets.
More recently I have collaborated with collegues in the Physics Department (Lancaster University) to investigate the role of transmembrane voltage in signal transduction and mechanisms underpinning selectivity of ion channels
The major research interests of my group concern the regulation of ion transport across the biological membranes of plant and fungal cells. Current areas of interest include:
Organic acid secretion and nutrient acquisition
Organic acid secretion from higher plant roots and fungi into the soil solution plays an important role in nutrient acquisition and metal ion detoxification. Surprisingly, the pathways by which organic acids cross the plasma membrane of cells are not well characterised and little is known of the molecular mechanisms that regulate the exudation of organic acids. We are currently characterising anion channel activity in Aspergillus nidulans and the root of Arabidopsis. We have identified a novel organic acid efflux channels in the plasma membrane of Arabidopsis epidermal root cells (e.g. Diatloff et al., 2004) and Fungi (e.g. Roberts et al. 2013). The regulation of these channels suggest that these transporters probably play a role in phosphate acquisition and other nutrient acquisition.
Calcium signalling in filamentous fungi
Fungi are a diverse but discrete group of organisms with a myriad of activities, many of which impact both directly and indirectly on mankind. Thus understanding how these organisms respond and adapt to their environment is of fundamental importance. Cytosolic Ca2+ has been established as a ubiquitous intracellular signal molecule, essential for the transduction of a wide variety of environmental stimuli in eukaryotic cells. However, despite a strong body of evidence showing key roles for Ca2+ signal transduction in filamentous fungi, our understanding of Ca2+ signalling in these organisms is not well developed. One of the main reasons for this is our current ignorance of Ca2+-permeable channel activity (which is responsible for mediating cytosolic Ca2+ signalling events) in filamentous fungi. Work is ongoing to address this fundamental gap in our knowledge; namely, to identify and functionally characterise Ca2+ permeable channels in filamentous fungi. This work is taking advantage of recent developments in fungal genomics, initially leading to the identification of a number of candidate genes that are likely to encode Ca2+ permeable ion channels (and thus play key roles in Ca2+ signalling) in the model filamentous fungus, Aspergillus nidulans. A multidisciplinary approach, combining a range of molecular biological and cell biological techniques, is being employed.
Physical origins of selectivity and permeation of ion channels
I currently collaborate with the Medical Physics Group (Lancaster; headed by Professor McClintock) to investigate fundamental properties of ion channels. Specifically, we have recieved EPSRC funding to develop a novel biophysical model towards understanding of ion permeation through ion channels. My role in this collaboration is to electrophysiological recordings of the Na+ selective channel, NaChBAC, expxressed in CHO cells. Site-directed mutagenesis will be employed to test predictions and validate the model.
I am the Director of Studies for Biological Sciences Programmes.
Currently I teach on the following modules:
BIOL121 Impact of Microbes: I cover Viruses and Fungi.
BIOL201 Biochemistry: I cover Citric Acid Cycle, Amino Acid Metabolism and Bioenergetics
BIOL211 Cell Biology: I cover Membrane Transport (Ion Channels, Carriers and Pumps)
BIOL302 Signalling Transport and Disease: I build on second year material and focuss on ion channels in human physiology and discuss ion channel diseases.
BIOL387 Bioscience Research Project: Student projects in Cell Biology with a focus on Ion Channels.
BIOL390 Bioscience Literature Review: literature reviews in microbiology and cell biology
2000 Wellcome Trust Research Career Development Fellowship The role of plasma membrane ion channels in fungal growth - potential targets for fungicides £311,656
2001 Lancaster University Small Grant Scheme Purchase of equipment for novel investigations of transporters in fungal membranes (directly contributed to successful BBSRC award 2003) £6096
2001 BBSRC Committee Studentship award for investigation of anion transport in Arabidopsis roots
2001 BBSRC project grant Release of organic acid to the rhizosphere: a role for anion channels.(with Professor D Sanders and Dr M. Roberts) £209, 216
2002 BBSRC equipment grant Using modern molecular and cellular techniques to interpret plant responses to environmental change (Co-applicant with Professors RD Bardgett, WJ Davies, AM Hetherington, BG Forde and PJ Lea, and Drs JE Taylor, ND Paul, MR McAinsh). £1,053,816
2003 BBSRC grant “Developing Pichia pastoris as a heterologous expression system for ion transporters” (with Professor B Forde) £99, 169
2004 Knowledge Transfer Partnership (KTP) award part funded by the Department for Trade and Industry (via the BBSRC) and Micap plc. Developing novel encapsulation technology to protect and control the release of active ingredients from yeast. (with Dr C Price) £135,323.
2009 Research and Enterprise Services (Lancaster University) award to identify transmembrane anion transporters responsible for citric efflux from Aspergillus niger £2000
2010 Research and Enterprise Services (Lancaster University) award to identify transmembrane anion transporters responsible for citric efflux from Aspergillus niger (extension) £3500
2010 University Hospitals of Morecambe Bay NHS Foundation Trust funded (Leese bequest) studentship - Modelling the role of the endothelium in cardiovascular physiology (with Dr J Owen-Lynch and Professor A Stefanovska) £61,000
2014 Faculty Research Investment Fund (FHM, Lancaster University) Synthesis and functional expression of a novel NaChBac concatamer (with Michael Ginger) £2100
2014 EPSRC project grant Ionic Coulomb blockade oscillations and the physical origins of permeation, selectivity and their mutation transformations in biological ion channels (Co-Investigator with Medical Physics Group, Physics Department – Professors PVE McClintock and A. Stefanovska, Drs D Luchinsky and I Kaufmann) £993,065
2015 Sensory perception in Acanthameoba cyst: molecular mechanisms and electrophysiological properties. (co-Investigator with Dr Siddiqui and Professor Khan at Sunway University)
On the selectivity of the NaChBac channel: an integrated computational and experimental analysis of Sodium and Calcium permeation
Guardiani, C., Fedorenko, O., Roberts, S.K., Khovanov, I.A. 28/11/2017 In: Physical Chemistry Chemical Physics. 19, 44, p. 29840-29854. 15 p.
Ionic Coulomb blockade and anomalous mole fraction effect in the NaChBac bacterial ion channel and its charge-varied mutants
Kaufman, I.K., Fedorenko, O., Luchinsky, D., Gibby, W., Roberts, S.K., McClintock, P.V.E., Eisenberg, R.S. 11/09/2017 In: EPJ Nonlinear Biomedical Physics. 5, 8 p.
Sodium binding sites and permeation mechanism in the NaChBac channel: a molecular dynamics study
Guardiani, C., Rodger, P.M., Fedorenko, O., Roberts, S.K., Khovanov, I.A. 14/03/2017 In: Journal of Chemical Theory and Computation. 13, 3, p. 1389-1400. 12 p.
Ionic Coulomb blockade and anomalous mole fraction effect in NaChBac bacterial ion channels
Kaufman, I.K., Fedorenko, O.A., Luchinsky, D.G., Gibby, W.A.T., Roberts, S., McClintock, P.V.E., Eisenberg, R.S. 8/12/2016 In: arXiv.
Valproate inhibits MAP kinase signalling and cell cycle progression in S. cerevisiae.
Desfossés-Baron, K., Hammond-Martel, I., Simoneau, A., Sellam, A., Roberts, S.K., Wurtele, H. 26/10/2016 In: Scientific Reports. 6, p. 1-14. 14 p.
Calcium dependence of Eugenol tolerance and toxicity in Saccharomyces cerevisiae
Roberts, S., McAinsh, M., Cantopher, H., Sandison, S. 18/07/2014 In: PLoS ONE. 9, 7, 8 p.
Calcium imaging of the cyclic nucleotide response
McAinsh, M., Roberts, S., Dubovskaya, L. 2013 In: Cyclic nucleotide signalling in plants. New York : Humana Press p. 107-119. 13 p. ISBN: 9781627034401. Electronic ISBN: 9781627034418.
Cch1p mediates Ca2+ influx to protect Saccharomyces cerevisiae against eugenol toxicity
Roberts, S., McAinsh, M., Widdicks, L. 13/09/2012 In: PLoS ONE. 7, 9, 7 p.
Characterisation of AnBEST1, a functional anion channel in the plasma membrane of the filamentous fungus, Aspergillus nidulans.
Roberts, S., Milnes, J., Caddick, M. 09/2011 In: Fungal Genetics and Biology. 48, 9, p. 928-938. 10 p.
A CLC chloride channel plays an essential role in copper homeostasis in Aspergillus nidulans at increased extracellular copper concentrations.
Odden, D.M., Diatloff, E., Roberts, S.K. 1/10/2007 In: Biochimica et Biophysica Acta (BBA) - Biomembranes. 1768, 10, p. 2466-2477. 12 p.
Expression and transport characterisation of the wheat low-affinity cation transporter (LCT1) in the methylotrophic yeast Pichia pastoris.
Diatloff, E., Forde, B.G., Roberts, S.K. 9/06/2006 In: Biochemical and Biophysical Research Communications. 344, 3, p. 807-813. 7 p.
Plasma membrane anion channels in higher plants and their putative functions in roots.
Roberts, S.K. 03/2006 In: New Phytologist. 169, 4, p. 647-666. 20 p.
The Saccharomyces cerevisiae Ca2+ channel Cch1pMid1p is essential for tolerance to cold stress and iron toxicity.
Peiter, E., Fischer, M., Sidaway, K., Roberts, S.K., Sanders, D. 24/10/2005 In: FEBS Letters. 579, 25, p. 5697-5703. 7 p.
Phosphate-dependent anion channel-mediated citrate efflux from Arabidopsis roots
Diatloff, E., Roberts, M., Sanders, D., Roberts, S. 07/2005
The Saccharomyces cerevisiae Ca2+ channel Cch1pMid1p reveals a role for Ca2+ influx in iron tolerance
Peiter, E., Fischer, M., Sidaway, K., Roberts, S.K., Sanders, D. 07/2005
Characterization of Anion Channels in the Plasma Membrane of Arabidopsis Epidermal Root Cells and the Identification of a Citrate-Permeable Channel Induced by Phosphate Starvation.
Diatloff, E., Roberts, M., Sanders, D., Roberts, S.K. 12/2004 In: Plant Physiology. 136, 4, p. 4136-4149. 14 p.
Differential regulation of K+ channels in Arabidopsis epidermal and stelar root cells.
Diatloff, E., Geiger, D., Shang, L., Hedrich, R., Roberts, S.K. 08/2004 In: Plant, Cell and Environment. 27, 8, p. 980-990. 11 p.
Anion channels in roots : a role in sulphate transport.
Diatloff, E., Brown, R., Roberts, S.K. 03/2004 In: Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology. 137, 3 Supp, p. S240.
Investigation into the functions of CLC channels in the filamentous fungus Aspergillus nidulans.
Oddon, E., Diatloff, E., Roberts, S.K. 03/2004 In: Comparative Biochemistry and Physiology - Part A: Molecular and Integrative Physiology. 137, 3 Supp, p. S196-S197.
Mitochondria provide the main source of cytosolic ATP for activation of outward-rectifying K+ channels in mesophyll protoplast of chlorophyll-deficient mutant rice (OsCHLH) seedlings.
Goh, C., Jung, K., Roberts, S.K., McAinsh, M., Hetherington, A.M., Park, Y.I., Suh, K.H. 20/02/2004 In: Journal of Biological Chemistry. 279, 8, p. 6874-6882. 9 p.
TOK homologue in Neurospora crassa : first cloning and functional characterisation of an ion channel in a filamentous fungus.
Roberts, S.K. 02/2003 In: Eukaryotic Cell. 2, 1, p. 181-190. 10 p.
A Novel Low-Affinity H⁺-Cl⁻ Co-Transporter in Yeast: Characterization by Patch Clamp
Roberts, S.K., Dixon, G.K., Fischer, M., Sanders, D. 07/2001 In: Mycologia. 93, 4, p. 636-633. 4 p.
The effects of ABA on channel mediated K+ transport across higher plant roots.
Roberts, S.K., Snowman, B.N. 09/2000 In: Journal of Experimental Botany. 51, 350, p. 1585-1594. 10 p.
Divalent Cation Block of Inward Currents and Low-Affinity K+ Uptake in Saccharomyces cerevisiae.
Roberts, S.K., Fischer, M., Dixon, G.K., Sanders, D. 01/1999 In: Journal of Bacteriology. 181, 1, p. 291-297. 7 p.
Divalent cation block of inward currents and low-afinity K+ uptake in Saccharomyces cerevisiae
Roberts, S.K., Fischer, M., Dixon, G.K., Sanders, D. 01/1999 In: Journal of Bacteriology. 181, 1, p. 291-297. 7 p.
Regulation of K+ channels in maize roots by water stress and abscisic acid
Roberts, S.K. 01/1998 In: Plant Physiology. 116, 1, p. 145-153. 9 p.
Integration of ion channel activity in calcium signalling pathways
Sanders, D., Allen, G.J., Muir, S.R., Roberts, S.K. 1998 In: Cellular Integration of Signalling Pathways in Plant Development. Berlin : Springer Verlag p. 47-58. 12 p.
Laser ablation of the cell wall and localized patch clamping of the plasma membrane in the filamentous fungus Aspergillus: characterization of an anion-selective efflux channel
Roberts, S.K., Dixon, G.K., Dunbar, S.J., Sanders, D. 12/1997 In: New Phytologist. 137, 4, p. 579-585. 7 p.
Permeation of Ca2+ and monovalent cations through an outwardly rectifying channel in maize root stelar cells
Roberts, S.K., Tester, M. 04/1997 In: Journal of Experimental Botany. 48, 309, p. 839-846. 8 p.
A patch clamp study of Na+ transport in maize roots
Roberts, S.K., Tester, M. 03/1997 In: Journal of Experimental Botany. 48, p. 431-440. 10 p.
Inward and outward K+-selective currents in the plasma membrane of protoplasts from maize root cortex and stele
Roberts, S.K., Tester, M. 12/1995 In: The Plant Journal. 8, 6, p. 811-825. 15 p.
Cytoplasmic calcium and Fucus egg activation
Roberts, S., Gillot, I., Brownlee, C. 01/1994 In: Development. 120, 1, p. 155-163. 9 p.
The role of Ca2+ in signal-transduction following fertilization in Fucus serratus
Roberts, S., Berger, F., Brownlee, C. 1/11/1993 In: Journal of Experimental Biology. 184, p. 197-212. 16 p.
Calcium and related channels in fertilization and early development of Fucus
Taylor, A.R., Roberts, S., Brownlee, C. 29/10/1992 In: Philosophical Transactions B: Biological Sciences. 338, 1283, p. 97-104. 8 p.