Crystallographic Studies Of Non-canonical Peptides Binding To MHC Class I Molecules.
Funder
National Health and Medical Research Council
Funding Amount
$489,750.00
Summary
Virus infected cells and cancer cells are recognised and eliminated from our body by specialised cells called T-cell lymphocytes. This recognition process is the key step in the immune response and some fundamental questions in immunology are centred on the nature of this process. At the molecular level, the recognition is mediated by the specific interaction between proteins on the surface of the cells. On the T-cell lymphocyte, the T-cell receptor (TCR) binds specifically to a protein called t ....Virus infected cells and cancer cells are recognised and eliminated from our body by specialised cells called T-cell lymphocytes. This recognition process is the key step in the immune response and some fundamental questions in immunology are centred on the nature of this process. At the molecular level, the recognition is mediated by the specific interaction between proteins on the surface of the cells. On the T-cell lymphocyte, the T-cell receptor (TCR) binds specifically to a protein called the MHC on the surface of the target cell. The target cell can be a cancer cell, or an infected antigen presenting cell (specialised cells in the body which present protein fragments (peptides) on their surface via MHC). The structure of a TCR and TCR-MHC have been solved in terms of the shape of the molecules at atomic resolution, bringing detailed information on how these two proteins interact with each other. In this proposal the structural basis of antigen presentation and recognition in cell-mediated immunity will be determined by three-dimensional structures of different peptides on MHC by x-ray crystallography. Cell surface antigen presentation by MHC molecules is crucial for initiating the cellular immune response against invading pathogens and cancer. This proposal encompasses a combined biochemical, immunological, and biophysical approach to understand the range of ligands which can bind to MHC which are subsequently recognised by the TCR. To understand the antigenic properties of modified peptides at the structure level, the x-ray structure of MHC with modified bound synthetic peptides will be determined.Read moreRead less
The Role Of Molecular Chaperones And Proteases In Mitochondrial Function
Funder
National Health and Medical Research Council
Funding Amount
$432,750.00
Summary
Mitochondria are essential organelles providing the cell with essential molecules and being the source of oxidative energy in the cell. They are at the centre of many clinical conditions, ranging from genetic to common neurological diseases and other conditions related to ageing. We have been defining the way in which mammalian cells respond to the accumulation of unfolded proteins within the mitochondrial compartment and have found this produces what we have called the Mitochondrial Stress Resp ....Mitochondria are essential organelles providing the cell with essential molecules and being the source of oxidative energy in the cell. They are at the centre of many clinical conditions, ranging from genetic to common neurological diseases and other conditions related to ageing. We have been defining the way in which mammalian cells respond to the accumulation of unfolded proteins within the mitochondrial compartment and have found this produces what we have called the Mitochondrial Stress Response, a process that results in the selective upregulation of a suite of genes encoding mitochondrial stress proteins. This application deals with the question of the consequences to the cell of the creation of proteolytic environment. We have found that the two major proteases of the mitochondrion are upregulated and that this results in a marked increase in the rate of degradation of mitochondrial proteins. We aim to determine the specific roles of individual proteases in this process and the consequences of this proteolysis on the efflux of peptides from the mitochondria. This question has important medical implications, as one of the consequences of defects in mitochondrial function is the loss of cells from the affected tissue. We will also address the question of how mitochondrial biogenesis is regulated. We have recently found that the cytosolic molecular chaperone Hsp90 is required for protein import into mitochondria in mammalian cells. Since Hsp90 has hitherto been shown to be a key regulatory component in the steroid hormone and tyrosine kinase signalling pathways, this finding raises the possibility that protein import and thereby mitochondrial biogenesis may be regulated via the involvement of Hsp90.Read moreRead less
Antigen Selection In The MHC-restricted Cellular Immune Response
Funder
National Health and Medical Research Council
Funding Amount
$175,570.00
Summary
The body's white cells eliminate microorganisms through the actions of immune lymphocytes and other cells which conspire to kill and neutralise these unwanted guests. When microorganisms hide inside the cells of the body they are still detected by a set of T lymphocytes which have specific receptors for scrutinising the surface of cells for any changes which might signal an intracellular infection. The immune system is ever vigilant in its search for signs of infection which are generally appare ....The body's white cells eliminate microorganisms through the actions of immune lymphocytes and other cells which conspire to kill and neutralise these unwanted guests. When microorganisms hide inside the cells of the body they are still detected by a set of T lymphocytes which have specific receptors for scrutinising the surface of cells for any changes which might signal an intracellular infection. The immune system is ever vigilant in its search for signs of infection which are generally apparent when molecules called antigens are released by microorganisms and captured by the body's cells. This activates lymphocytes resulting in an immune response capable of eliminating the microorganisms. Scrutiny of the body's cells by lymphocytes occurs continuously even when there is no infection present in the body. Following infection of a cell, microbial antigens reveal the infection by their appearance on the cell surface where they are detected by the immune system's lymphocytes. This occurs through a mechanism called antigen presentation. During antigen presentation the proteins inside the cell, including those of any invading microorganism, are first degraded into shorter molecules called peptides. This event is called antigen processing. A fraction of the peptides created by antigen processing are captured by specialised receptors present on all cells. These receptors are called HLA or histocompatibility molecules. This project examines the molecular events which mediate the capture of peptide antigens by HLA molecules. The main focus is on those peptide antigens which elicit killer T cell responses by the immune system. A knowledge of how these peptides are selected for presentation and how they are captured and carried to the cell surface is fundamental to understanding immune responses to microorganisms, tumours, allergens, transplants and self tissues as in autoimmunity. Therefore the study is of great general relevance.Read moreRead less
Tapasin And Major Histocompatibility Complex Class I Antigen Presentation
Funder
National Health and Medical Research Council
Funding Amount
$226,650.00
Summary
An effective T cell response (cellular immune response) to infections is vital to a functional immune system. Normally, proteins are cleaved into small molecules called peptides and these peptides are in turn presented by Major Histocompatibility Complex molecules to T cells. However, we have only partial understanding of what determines the choice of peptides that are finally presented to T cells. Recent research suggests that a molecule called tapasin may also influence the choice of peptides. ....An effective T cell response (cellular immune response) to infections is vital to a functional immune system. Normally, proteins are cleaved into small molecules called peptides and these peptides are in turn presented by Major Histocompatibility Complex molecules to T cells. However, we have only partial understanding of what determines the choice of peptides that are finally presented to T cells. Recent research suggests that a molecule called tapasin may also influence the choice of peptides. This research proposal aims to examine the role of tapasin in this regard. A thorough understanding of the basic principles of peptide presentation to T cells is crucial to the design of effective vaccines. Furthermore it will also broaden our understanding of immunological responses to cancer, autoimmune diseases and infections.Read moreRead less
This project will unleash the potential of peptide drugs by overcoming their final barrier to widespread use, their synthesis. Plants naturally produce ultra-stable cyclic peptides. We will co-opt their machinery to produce in seeds, two drug leads that have potential as treatments for prostate cancer and chronic neuropathic pain. As an �organic� drug source, seeds have the potential to improve patient compliance and low-tech production systems will allow technology transfer to third-world natio ....This project will unleash the potential of peptide drugs by overcoming their final barrier to widespread use, their synthesis. Plants naturally produce ultra-stable cyclic peptides. We will co-opt their machinery to produce in seeds, two drug leads that have potential as treatments for prostate cancer and chronic neuropathic pain. As an �organic� drug source, seeds have the potential to improve patient compliance and low-tech production systems will allow technology transfer to third-world nations.Read moreRead less
Mimicking Protein Surfaces With Cyclic Peptides: W-conotoxin GVIA Mimics As Novel Analgesic And Neuroprotective Agents
Funder
National Health and Medical Research Council
Funding Amount
$216,412.00
Summary
The omega-conotoxins are small polypeptides (of around 25 residues) cross-linked by three disulfide bonds. At least two of these, omega-conotoxins GVIA and MVIIA, are potent and selective blockers of N-type voltage-gated calcium channels. Administered to the CNS via an intrathecal catheter, MVIIA and GVIA are analgesic in acute, chronic and neuropathic pain models, and protective following ischaemia-induced neuronal injury, such as occurs following stroke. They do not suffer from the development ....The omega-conotoxins are small polypeptides (of around 25 residues) cross-linked by three disulfide bonds. At least two of these, omega-conotoxins GVIA and MVIIA, are potent and selective blockers of N-type voltage-gated calcium channels. Administered to the CNS via an intrathecal catheter, MVIIA and GVIA are analgesic in acute, chronic and neuropathic pain models, and protective following ischaemia-induced neuronal injury, such as occurs following stroke. They do not suffer from the development of tolerance, in contrast with the opioids, such as morphine, which lose their analgesic potency over time and have undesirable side effects. We have determined the three-dimensional structure of GVIA and mapped onto that structure its calcium channel binding surface. This information is a starting point for the structure-based design of truncated and stabilised peptidic analogues of GVIA, which should have several advantages over the native polypeptides as candidates for the treatment of chronic pain and ischaemia-induced neuronal damage. In the course of this work we shall also generate a range of libraries of experimentally determined and predicted structures based on small, cyclic peptides. These libraries will be valuable tools for mimicking key functional regions of protein surfaces in small molecules that are easily (and cheaply) synthesised and have potentially favourable bioavailability. Thus, this project will also increase our understanding of the attributes of small cyclic peptides as mimics of functionally important protein surfaces and provide valuable tools for the design and evaluation of such peptides.Read moreRead less