Functions of Serpins in Plants and Algae
Serpins are a family of proteins with unusual properties including structural metastability and an ability to undergo large conformational change. Most serpins are potent, irreversible inhibitors of proteinases, most commonly serine proteinases of the chymotrypsin family. While many distinct roles are known for serpins in animals, such as regulation of blood coagulation (e.g. antithrombin), control of complement activation (e.g. C1 inhibitor) and transport of hormones (e.g. corticosteroid binding globulin), the functions of serpins in plants and algae are largely unknown.
Researchers in my lab work on serpin function in a range of model organisms including the unicellular green alga Chlamydomonas reinhardtii, the eudicot plant Arabidopsis thaliana (thale cress) and the monocot plant Oryza sativa (rice). Our approach includes quantitative analysis of gene expression, gene silencing, production and characterization of recombinant serpins and immunomicroscopy. My senior collaborators are plant biochemist Jørn Hejgaard (Technical University of Denmark, now retired), plant molecular biologist Robert Fluhr (Weizmann Institute, Israel), structural biologist Paul Curmi (University of New South Wales, Sydney, Australia) and plant physiologist Brian Atwell (Macquarie University).
A PhD student in my lab who graduated in 2009 with a thesis entitled 'Functional Characterization of Serpins in Plants and Green Algae using Reverse Genetics', Joon-Woo Ahn, showed that two specific serpins in Arabidopsis are involved in growth responses to plant treatment with methane methylsulfonate (MMS), a alkylating agent that causes DNA damage (Ahn et al., 2009). Sheila Franics from my lab completed her MPhil degree in 2010 with a thesis entitled 'Identification and Expression of Serpin Genes in Rice'. A PhD student from my lab, Renan Ersoy, completed his PhD thesis in 2011 entitled 'Functional Expression Analyses of Serpin Genes in Arabidopsis and Rice'. Please see the link at the bottom of this page for my Plant Serpins webpage.
Please contact me if you are interested in conducting research on plant or algal serpins as a PhD, MPhil or Honours student in my lab.
Effects of Climate Change on Food Allergens
Atmospheric CO2 concentration is steadily increasing but the effect of this and other parameters linked to climate change on the concentrations of allergens in food products is unknown. My PhD student Nicole Walczyk (Macquarie University) along with Penny Smith (University of Sydney), Euan Tovey (Woolcock Institute for Medical Research), Brian Atwell (Macquarie University) and Paul Beggs (Macquarie University) and I use peanut plants as a model for this research. In 2010 Nicole presented her research findings at three conferences in Germany. She plans to complete her PhD research in late-2011.
Functions of Proteins in Wheat Bran
In collaboration with Robert Willows, Brian Atwell and PhD student Tony Jercovic (all at Macquarie University) I work on identification and function of proteins in the bran of wheat (Jerkovic et al., 2010). Techniques used are microdissection of bran layers, proteomics, immunolocalization and enzyme assays.
Responses of Rice to an Energy Crisis
Brian Atwell together with his PhD student Joshua Edwards and I work on responses of rice to shortages of ATP. We currently use hypoxia and anoxia to challenge rice coleoptiles to determine which physiological processes are most affected by an energy deficit.
Refereed Articles and Book Chapters
Roberts TH, Lampl N and Fluhr R (2011). Plants and the study of serpin biology. Methods in Enzymology 499, 347-66
Lampl N, Budai-Hadrian O, Davydov O, Joss TV, Harrop SJ, Curmi PMG, Roberts TH and Fluhr R (2010). Arabidopsis AtSerpin1: crystal structure and in vivo interaction with its target protease RESPONSIVE TO DESICCATION-21 (RD21). Journal of Biological Chemistry 285, 13550-60
Jerkovic A, Kriegel AM, Bradner JR, Atwell BJ, Roberts TH and Willows RD (2010). Strategic distribution of protective proteins within bran layers of wheat (Triticum aestivum L.) protects the nutrient-rich endosperm. Plant Physiology 152, 1459-70
Ahn J-W, Atwell BJ and Roberts TH (2009). Serpin genes AtSRP2 and AtSRP3 are required for normal growth sensitivity to a DNA alkylating agent in Arabidopsis. BMC Plant Biology 9, Art 52 (11 pp)
Mak Y, Willows RD, Roberts TH, Wrigley CW, Sharp PJ and Copeland L (2009). Germination of wheat: a functional proteomics analysis of the embryo. Cereal Chemistry 86, 281-9
Peterson RA, Bradner JR, Roberts TH and Nevelainen KMH (2009). Fungi from koala (Phascolartos cinerus) faeces produce enzymes with activities against a range of recalcitrant substrates. Letters in Applied Microbiology 48, 218-25
Roberts TH and Hejgaard J (2008). Serpins in plants and green algae. Functional & Integrative Genomics 8, 1-27
Haynes PA and Roberts TH (2007). Subcellular shotgun proteomics in plants: looking beyond the usual suspects. Proteomics 7, 2963-75
Hejgaard J and Roberts TH (2007). Plant Serpins. Chapter 12 in Silverman GA & Lomas DA (eds). Molecular and Cellular Aspects of the Serpinopathies and Disorders in Serpin Activity. World Scientific. ISBN 981-256-963-4
Mak Y, Willows RD, Roberts TH, Wrigley CW, Sharp PJ and Copeland L (2006). Black Point is associated with reduced levels of stress-, disease- and defense-related proteins in wheat grain. Molecular Plant Pathology 7, 177-89
Hejgaard J, Laing WA, Marttila S, Gleave AP and Roberts TH (2005). Serpins in fruit and vegetative tissues of apple (Malus domestica): expression of four serpins with distinct reactive centres and characterization of a major inhibitory seed form, MdZ1b. Functional Plant Biology 32, 517-27
Roberts TH , Hejgaard J, Saunders DE, Cavicchioli R and Curmi PM (2004). Serpins from unicellular Eukarya , Archaea and Bacteria : sequence analysis and evolution. Journal of Molecular Evolution 59, 437-47
Austin C, Mizdrak J, Matin A, Sirijovski N, Kosim-Satyaputra P, Willows RD, Roberts TH, Truscott RJW, Polekhina G, Parker MW and Jamie JF (2004). Optimised expression and purification of recombinant human indoleamine 2,3-dioxygenase. Protein Expression and Purification 37, 392-8
Roberts TH , Marttila S, Rasmussen SK and Hejgaard J (2003). Differential gene expression for suicide-substrate serine proteinase inhibitors (serpins) in vegetative and grain tissues of barley. Journal of Experimental Botany 54, 2251-63
Willows RD, Lake V, Roberts TH and Beale SI (2003). Regulation of Mg chelatase during transition from anaerobic growth in Rhodobacter capsulatus. Journal of Bacteriology 185, 3249-58
Hansson A, Willows RD, Roberts TH and Hansson M (2002). Three semidominant barley mutants with single amino acid substitutions in the smallest magnesium chelatase subunit form defective AAA + hexamers. Proceedings of the National Academy of Sciences USA 99, 13944-9. This article above was featured in Science (298, 325) as an 'Editors' Choice'.
Østergaard H, Rasmussen SK, Roberts TH and Hejgaard J (2000). Inhibitory serpins from wheat grain with reactive centers resembling glutamine-rich repeats of prolamin storage proteins: cloning and characterization of five major molecular forms. Journal of Biological Chemistry 275, 33272-9
Roberts TH and Lees EM (1997). Glyoxylate aminotransferase activities in developing fruits of legumes. Journal of Biochemistry, Molecular Biology and Biophysics 1, 63-71
Møller IM, Roberts TH and Rasmusson AG (1996). Ubiquinone-1 induces external deamino-NADH oxidation in potato tuber mitochondria. Plant Physiology 112, 75-8
Roberts TH , Rasmusson AG and Møller IM (1996). Platanetin and 7-iodo-acridone-4-carboxylic acid are not specific inhibitors of respiratory NAD(P)H dehydrogenases in potato tuber mitochondria. Physiologia Plantarum 96, 263-7
Melo AMP, Roberts TH and Møller IM (1996). Two rotenone-insensitive internal NAD(P)H dehydrogenases are coupled to the electron transport chain in plant mitochondria. Biochimica et Biophysica Acta 1276, 133-9
Roberts TH , Fredlund KM and Møller IM (1995). Direct evidence for the presence of two external NAD(P)H dehydrogenases coupled to the electron transport chain in plant mitochondria. FEBS Letters 373, 307-9
PhD Thesis (1995)
Glyoxylate aminotransferases and ureide catabolism in the developing fruits of legumes. University of Sydney