Snapshots of an enzyme in action: structural and mechanistic studies on the catalytic cycle of Escherichia coli ketol-acid reductoisomerase. Enzymes are required for almost every process that occurs in a living organism. For this reason, understanding how enzymes work is essential if we are to understand life itself. In this project we will investigate the enzyme KARI by capturing a series of snapshots of its atomic structure as it progresses through its working cycle. In addition, we will make ....Snapshots of an enzyme in action: structural and mechanistic studies on the catalytic cycle of Escherichia coli ketol-acid reductoisomerase. Enzymes are required for almost every process that occurs in a living organism. For this reason, understanding how enzymes work is essential if we are to understand life itself. In this project we will investigate the enzyme KARI by capturing a series of snapshots of its atomic structure as it progresses through its working cycle. In addition, we will make a series of small alterations to the atomic structure that will allow us to understand how the individual parts work together.Read moreRead less
Structure and inhibition of acetohydroxyacid synthase. Acetohydroxyacid synthase (AHAS) has been identified as the target for several widely used herbicides known as the sulfonylureas and imidazolinones. World-wide, these two herbicides account for $US2 billion in annual sales. The aim is to determine the three-dimensional structure of AHAS from several sources and in complex with these herbicides. Furthermore, AHAS appears to be an excellent target for the development of antibacterial compounds ....Structure and inhibition of acetohydroxyacid synthase. Acetohydroxyacid synthase (AHAS) has been identified as the target for several widely used herbicides known as the sulfonylureas and imidazolinones. World-wide, these two herbicides account for $US2 billion in annual sales. The aim is to determine the three-dimensional structure of AHAS from several sources and in complex with these herbicides. Furthermore, AHAS appears to be an excellent target for the development of antibacterial compounds and fungicides. Knowledge of the three dimensional structures of these enzymes will be important in the rational design of more effective inhibitors with improved selectivity.Read moreRead less
Molecular mechanisms of pilin glycosylation in Neisseria: a model system for protein glycosylation in bacteria. The disease causing bacteria Neisseria meningitidis and Neisseria gonorrhoeae are important human pathogens. Cell surface structures, called pili, are known to be important in allowing the bacteria to stick to host cells. Genetic and structural studies have identified that the protein subunits, which make up pili, are glycosylated - modified by the addition of sugars. Until recently ....Molecular mechanisms of pilin glycosylation in Neisseria: a model system for protein glycosylation in bacteria. The disease causing bacteria Neisseria meningitidis and Neisseria gonorrhoeae are important human pathogens. Cell surface structures, called pili, are known to be important in allowing the bacteria to stick to host cells. Genetic and structural studies have identified that the protein subunits, which make up pili, are glycosylated - modified by the addition of sugars. Until recently glycosylation of Gram-negative bacterial proteins was not thought to occur, however our recent work with these bacteria, and other groups studying Pseudomonas and Campylobacter, have shown that this process may be widespread. In our previous studies, we have identified and analysed a number of genes involved in pili glycosylation, in bacteria, which make known sugar structures. We have used this information to developed models for how the biochemistry and physiology of the glycosylation system may work. With a well-established structure and many genes already identified, glycosylation in Neisseria represents the best available model system to study this novel and important process. In the proposed study we describe experiments planned to test our models and reveal the molecular detail of this process. This study could lead to major advances in our understanding of this process and, when understood, may have future applications in biotechnology.Read moreRead less
Host-pathogen interactions: the role of mimicry. The proposed research program, using a combination of structure and functional analysis will provide insight into the mechanism of nucleotide hydrolysis by the enzymes NTPDases. This study will not only improve our fundamental understanding of NTPDase action but could lead to the rational design of antimicrobials.
Insect development : the role of cytochrome P450s. Pest insects vector human diseases such as malaria and impose a massive burden in agriculture due to control costs and production losses. The intelligent control of insect pests requires an understanding of their development that is controlled by hormones. This project will provide an in depth understanding of insect hormone synthesis/degradation that is controlled by a class of enzymes, the cytochrome P450s. This will increase the potential ....Insect development : the role of cytochrome P450s. Pest insects vector human diseases such as malaria and impose a massive burden in agriculture due to control costs and production losses. The intelligent control of insect pests requires an understanding of their development that is controlled by hormones. This project will provide an in depth understanding of insect hormone synthesis/degradation that is controlled by a class of enzymes, the cytochrome P450s. This will increase the potential for new insect-specific control strategies with a decreased environmental impact.Read moreRead less
Mechanistic Studies of Dimethylsulfide Dehydrogenase: A Novel Bacterial Molybdoenzyme. The aim of this proposal is to use electrochemical, spectroscopic and molecular biological techniques to understand the mechanism of action of the enzyme dimethylsulfide dehydrogenase. This enzyme is representative of an major group of molybdenum-containing enzymes that have importance in microbial biotransformations. The project will provide fundamental information about a multi-redox centre protein that has ....Mechanistic Studies of Dimethylsulfide Dehydrogenase: A Novel Bacterial Molybdoenzyme. The aim of this proposal is to use electrochemical, spectroscopic and molecular biological techniques to understand the mechanism of action of the enzyme dimethylsulfide dehydrogenase. This enzyme is representative of an major group of molybdenum-containing enzymes that have importance in microbial biotransformations. The project will provide fundamental information about a multi-redox centre protein that has potential application in biosensors and biocatalysis.Read moreRead less
Structural studies of catalysis and electron transfer by copper proteins. We propose to determine the crystal structures of five copper-containing proteins. Three are amine oxidases, enzymes that protect a wide range of organisms against toxic cell products (amines). Novel chemical modifications and crystallographic techniques will be used to test hypotheses for the enzyme mechanism. The results will provide a basis for the future manipulation of the enzymes' activities. Our other targets, s ....Structural studies of catalysis and electron transfer by copper proteins. We propose to determine the crystal structures of five copper-containing proteins. Three are amine oxidases, enzymes that protect a wide range of organisms against toxic cell products (amines). Novel chemical modifications and crystallographic techniques will be used to test hypotheses for the enzyme mechanism. The results will provide a basis for the future manipulation of the enzymes' activities. Our other targets, sulfocyanin and auracyanin-A, perform essential electron-transfer functions in an archaeon and a photosynthetic bacterium, respectively. The determination of their molecular structures will answer exciting questions about electron transfer in primitive organisms, and about the evolution of copper proteins as biological electron-transfer agents.Read moreRead less
Investigation of a Novel Protein Implicated in Phosphate Metabolism in Bacteria. Phosphate is an important nutrient for all forms of life on Earth. A novel bacterial protein has been identified that appears to be important for the uptake or processing of phosphate, since mutants lacking the protein grow poorly inside certain cells of the human immune system (where phosphate levels are low) and in media containing low phosphate. The aims of this project are: to determine the role of the protein b ....Investigation of a Novel Protein Implicated in Phosphate Metabolism in Bacteria. Phosphate is an important nutrient for all forms of life on Earth. A novel bacterial protein has been identified that appears to be important for the uptake or processing of phosphate, since mutants lacking the protein grow poorly inside certain cells of the human immune system (where phosphate levels are low) and in media containing low phosphate. The aims of this project are: to determine the role of the protein by examining all phosphate containing molecules in our mutants; to determine its location in bacteria and functional domains; to identify other affected genes in our mutants; and, to find proteins that interact with this new protein. This project expects to demonstrate the importance of this protein in phosphate metabolism in bacteria.Read moreRead less
Novel mechanisms of bacterial arsenic metabolism - arsenate reduction and arsenite oxidation. Novel arsenic metabolising bacteria (i.e., arsenate respiring and arsenite oxidising), which are both phylogenetically and physiologically unique, have been isolated from arsenic-contaminated areas in Australia. The arsenate respiring bacterium, Chrysiogenes arsenatis, is of particular interest as it is the only organism reported able to respire with arsenate using the respiratory substrate acetate as t ....Novel mechanisms of bacterial arsenic metabolism - arsenate reduction and arsenite oxidation. Novel arsenic metabolising bacteria (i.e., arsenate respiring and arsenite oxidising), which are both phylogenetically and physiologically unique, have been isolated from arsenic-contaminated areas in Australia. The arsenate respiring bacterium, Chrysiogenes arsenatis, is of particular interest as it is the only organism reported able to respire with arsenate using the respiratory substrate acetate as the electron donor. It is proposed that physiological, biochemical and molecular biological studies be carried out to better understand the mechanisms by which these organisms metabolise arsenic. The knowledge gained from these studies will have worldwide application in the development of an arsenic bioremediation system.Read moreRead less
Functional evolution and therapeutic potential of snake venom coagulotoxins. This project aims to identify and understand the factors that influence the useful function of key residues (parts of larger compounds) in Australian snake venom coagulotoxins, which alter blood-clotting ability. In recent years, snake venom compounds have been demonstrated as useful models from which to synthesise therapeutic drugs to improve health and well-being. This project will test these important toxins on model ....Functional evolution and therapeutic potential of snake venom coagulotoxins. This project aims to identify and understand the factors that influence the useful function of key residues (parts of larger compounds) in Australian snake venom coagulotoxins, which alter blood-clotting ability. In recent years, snake venom compounds have been demonstrated as useful models from which to synthesise therapeutic drugs to improve health and well-being. This project will test these important toxins on model systems that represent natural prey items in order to determine the molecular and functional evolution of blood-clot forming enzymes. Expected outcomes include substantial contributions to the body of evolutionary biology knowledge, as well as narrowing the search for the ultimate drug candidates.Read moreRead less