Functions of Serpins in Plants and Algae
Serpins are a family of proteins with unusual properties including structural metastability and the ability to undergo large conformational change. Most serpins are 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 (antithrombin), control of complement activation (C1 inhibitor), and transport of hormones (corticosteroid binding globulin), the functions of serpins in plants and algae are unknown.
Researchers in my lab and I work on serpin function in a range of model organisms including the unicellular green alga Chlamydomonas reinhardtii, the eudicot plants 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. Senior collaborators include Jørn Hejgaard (Technical University of Denmark), Mark Baker (Chemistry & Biomolecular Sciences, Macquarie University) and Brian Atwell (Biological Sciences, Macquarie University).
Innovative Grain Foods CRC
Rob Willows, Brian Atwell and I work together with BRI Pty Ltd on a bioprocessing project for the Grain Foods CRC. This also involves industry partner George Weston Foods. We are investigating how biological processes might increase the yield and quality of flour. The work involves monitoring biochemical and structural changes that occur in grains prior to and during milling. Traditionally a technological field of inquiry driven by engineers, it has the potential for innovative biochemical discoveries with substantial industry application.
Refereed Papers
Roberts TH & Hejgaard J (2008). Serpins in plants and green algae. Functional & Integrative Genomics 8: 1-27
Haynes PA & Roberts TH (2007). Subcellular shotgun proteomics in plants: looking beyond the usual suspects. Proteomics 7: 2963-2975
Hejgaard J & 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 & Copeland L (2006). Black Point is associated with reduced levels of stress-, disease- and defense-related proteins in wheat grain. Molecular Plant Pathology 7: 177-189
Hejgaard J, Laing WA, Marttila S, Gleave AP & 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 : 517-527
Roberts TH , Hejgaard J, Saunders DE, Cavicchioli R & Curmi PM (2004). Serpins from unicellular Eukarya , Archaea and Bacteria : sequence analysis and evolution. Journal of Molecular Evolution 59 : 437-447
Austin C, Mizdrak J, Matin A, Sirijovski N, Kosim-Satyaputra P, Willows RD, Roberts TH , Truscott RJW, Polekhina G, Parker MW & Jamie JF (2004). Optimised expression and purification of recombinant human indoleamine 2,3-dioxygenase. Protein Expression and Purification 37 : 392-398
Roberts TH , Marttila S, Rasmussen SK & 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 & 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 & 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 U.S.A. 99 : 13944-9
This article was featured in Science ( 298 : 325) as an "Editors' Choice".
Østergaard H, Rasmussen SK, Roberts TH & 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 & 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 & Rasmusson AG (1996). Ubiquinone-1 induces external deamino-NADH oxidation in potato tuber mitochondria. Plant Physiology 112 : 75-8
Roberts TH , Rasmusson AG & 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 & 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 & 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.
