Dr Peter Anderson

Contact Details

Key Responsibilities

• Biotechnology

Teaching

• Biotechnology

Research

• Project 1: Structural and biochemical analysis of plant disease resistance proteins (in collaboration with A/Prof. B. Kobe University of Queensland, Drs P. Dodds and  J Ellis CSIRO Plant Industry Canberra).
  
  Plant cells have evolved mechanisms to detect a wide range of invading organisms.  In many cases a basal resistance response is activated by the plant upon recognition of a common molecular pattern found in many micro-organisms.  This is known as pathogen associated molecular pattern immunity or PAMP triggered immunity.  Some more sophisticated and “sneaky” pathogens have evolved the capacity to suppress PAMP triggered immunity by secreting effectors proteins into the plant cell.  This allows the pathogen to continue to colonise the plant, subvert the flow of nutrients in order to continue its lifecycle, and ultimately giving rise to the recognisable disease symptoms on the plant.  Rust fungi, and in particular the rust fungi of flax, are characteristic of this later form of plant colonisation, secreting effector proteins into plant cells.  The invaded host plant however, is not without defence against such pathogens.  Resistance, or R, proteins have a surveillance capacity to detect these effectors and mount a resistance response by the plant.  It is these R proteins and the corresponding effector proteins, in the flax/flax rust interaction, which are the target of this research collaboration.  Very little is known about the structure and specific function of both the R and effector proteins, how they interact, and how R protein sense the presence and trigger the resistance response.
  
  We have successfully manufactured recombinant flax rust resistance protein in the yeast, Pichia pastoris, and purified the protein to near homogeneity (Schmidt et al Plant J 50:1107-1117). This has provided the starting point to crystallise the protein and obtain its 3D structure. In the laboratories of our collaborators, the rust effector genes and the proteins they encode have been isolated.  One rust effector protein has been crystallised and its 3D structure determined (Wang et al Plant Cell Plant Cell 19:2898-2912). With purified recombinant protein of both R and effector proteins, many research opportunities exist to further understand the biochemical function and structural nature of this important interaction that dictates the outcome of a rust infection. For instance, we wish, by in vitro protein-protein interaction to confirm, or otherwise, the direct interaction of flax R and flax rust effector proteins as demonstrated by Y-2-H analysis (Dodds, et al PNAS 103, 8888-93). Recombinant protein will also enable us to test the role of the putative nucleotide-binding domain in R protein activation.
  
  The structural and biochemical study of R proteins and their interacting partners has far reaching implications. This will form the basis for modifying existing resistance genes to confer resistance to new diseases, resulting in large economic benefits.
  
  
• Project 2: Production of recombinant proteins for use in the wine industry (in collaboration with Drs E. Waters and S. Schmidt Australian Wine Research Institute, Adelaide SA and Dr H. Swiegers CHR Hansen, Copenhagen Denmark).
  
  Fermentation of grape juice and down stream processing is often plagued by problems.  Haze in white wine is the result of poor storage of wine in combination with a high concentration of protein in the grape juice (most commonly pathogenesis related (PR) proteins).  It is the precipitation of these PR proteins that gives the wine a cloudy appearance. One project in collaboration with Drs Waters and Schmidt is to manufacture aspartic proteases from Botrytis cinerea in the hope of generating an enzymatic approach to reducing wine haze by proteolysis of the PR protein precipitates.
  
  Another project aims to engineer microbial carbon-sulphur B-lyases to be active at low pH experienced during grape juice fermentation.  The CS-lyases are responsible for the generation of desirable sensory compounds found mainly in wine wines made from varieties of Sauvignon Blanc grapes.  These enzymes however function poorly at the low pH experienced during grape fermentation and therefore this project aims to engineer tolerance to low pH into recombinant forms of the CS-lyases for use in the wine industry.  This project is being conducted in collaboration with Dr H. Swiegers CHR Hansen, Copenhagen Denmark.

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