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Merging Structural Biology with Chemical Biology: Structural Chemistry at Eskitis
| Content Provider | Semantic Scholar |
|---|---|
| Author | Hofmann, Andreas Wang, C. K. Osman, Asiah Camp, D. |
| Copyright Year | 2010 |
| Abstract | This review introduces the Structural Chemistry Program at Griffith University's Eskitis Institute, and provides a brief overview over its current and future research portfolio. Capitalising on the co-location with a unique library collection of small molecules, the Queensland Compound Library, our laboratory investigates the structure and function of proteins with the aim of learning about their molecular mechanisms. Consequently, these studies also feed into drug discovery and design. The thematic focus of our Program is on proteins involved in infection, inflammation and neurological diseases, and this review highlights a few of our recent research efforts in this area. 1 The Eskitis Institute at Griffith University Research at the Eskitis Institute, directed by Prof Ronald J Quinn, investigates novel drugand cell-based therapies for human diseases. The Institute consists of ten research groups headed by research-only Chief Investigators, and two Faculty groups who undertake research and teaching. The research groups work within in five thematic areas: Adult Stem Cell Biology, Neglected Diseases, Infection and Immunity, Cancer and Neurological Diseases. Research at the Institute, as well as the performance of individual groups, is regularly reviewed by the Scientific Advisory Board which includes three external members (Prof Chris Ireland, Dr George Moore, Dr Patrick Tan). The laboratories and a suite of world-class facilities are housed in two co-located buildings at Brisbane Innovation Park in close neighbourhood to Griffith University's Nathan Campus. An investment of AU$ 12m in the University and the Institute by the Queensland Government enabled construction of the second of the two buildings which commenced in late 2006 and became fully operational in April 2008. 2 About the Structural Chemistry Program Our Program was established in 2006 as one of ten research programs of the newly formed Eskitis Institute. Our laboratory complements the research portfolio of the Institute by providing structural information in order to understand protein mechanisms at the molecular level. To improve the knowledge of the molecular mechanisms of diseases as well as to identify possible sites of interference, one needs to have a solid understanding of the structure and functions of proteins, and their interactions with ligands, target proteins and membranes. With protein crystallography on the one hand and a variety of biophysical methods on the other, our laboratory investigates structure, shape and properties of proteins and establishes structure-function relationships to obtain a rationale for future therapeutic applications. This includes the investigation of protein-ligand complexes as part of the drug discovery and drug design process. Thematically, the Structural Chemistry Program focuses on two biological themes: proteins involved in (i) infection and inflammation, and (ii) neurological diseases. At protein level, our thematic focus is on cytoskeletal and membrane-associated proteins. Since the majority of proteins we investigate are made in-house, we employ a broad range of methods from molecular cloning, protein expression and purification, providing the basis for the “wet” part of structural studies. Following the usual biochemical validation of purified and concentrated protein samples (SDSPAGE, UV spectroscopy, mass spectrometry), the samples are subjected to structural investigation. The core method of our laboratory is protein X-ray crystallography, and diffraction experiments are carried out at the in-house diffractometer (Rigaku Micro Max-007 generator, R-Axis IV++ detector), as well as synchrotron beam lines. Protein single crystals are obtained by screening our extensive collection (> 1000) of crystallisation factorials using the sitting or hanging drop vapour diffusion technique. For investigation of protein molecular mechanisms and quaternary structure, we employ biophysical methods such as circular dichroism and fluorescence spectroscopy, multi-angle light scattering, X-ray and neutron scattering, isothermal titration calorimetry, membrane and monolayer adsorption. Since computational tasks are a major part of the structural investigation of proteins, the development of in-house software is an almost integral part of structural biology laboratories. Starting in 2002, when very few algorithms in this context were available in Java, we have been developing Java software applications for particular tasks with the aim of (i) establishing fundamental Java classes for basic operations in structural biology, and (ii) generating user-friendly, intuitive applications with graphical user interfaces for particular tasks arising in structural biology and biophysical chemistry [1; 2]. Since those days, efforts such as BioJava have grown significantly, and Java applications have now become an established part of structural biology computation. The applications developed by our laboratory are freely available for academic usage and can be downloaded from our home page (http://www.structuralchemistry.org/pcsb). The unique collection of small molecules at the Queensland Compound Library, consisting of natural and synthetic compounds, provides a valuable resource for structural investigation of proteins with probes as well as focused drug discovery programs (Figure 1). 3 Small molecule ligands for proteins irreplaceable tools for drug discovery and chemical biology Chemical biology examines biological systems through the application of chemical techniques and tools; its goal is to use small-molecule probes to discover specific biomolecular targets and pathways that are modulated by the particular compound [3]. Small molecules, in contrast to classical genetics where manipulation occurs at the DNA level, typically modulate protein function by inducing conformational changes or by competing for endogenous protein–ligand or protein–protein interaction sites, resulting in altered activity [4]. This allows temporal study of signalling pathways and the ability to wash-out probes to study reversible inhibition. Clearly, success derived from the innovative use of small-molecule techniques and tools depends on the creative interaction between chemistry and biology. Currently, biomedical research in Australia relies heavily on molecular biology techniques to identify biological targets and build understanding of the biological system responsible for a particular disease. These techniques allow investigators to eliminate specific proteins by ‘knocking out’ genes; increasing the concentrations of particular proteins by increasing the number of copies of the corresponding genes or by using a more active gene promoter; or altering the function of a protein by introducing specific mutations in the corresponding gene [5]. Although these methods are powerful in model organisms such as Saccharomyces cerevisiae and Drosophila melanogaster, mammals represent a significant experimental challenge to molecular biology approaches because of slower rates of reproduction, large sizes and large genomes. The chemical biology approach avoids these problems by studying the effect of small molecules on the mammalian proteome rather than the genome [5]. The Queensland Compound Library, described in more detail below, aims to facilitate biomedical research beyond classical molecular biology techniques and into new interdisciplinary sciences like chemical biology or chemical genetics, both of which require access to large diverse compound libraries. 4 Molecular libraries Small molecules are critical tools for understanding important cellular events and biological pathways involved in health and disease. Access to large, diverse and biologically relevant small-molecule compound libraries is essential to the advancement of knowledge in the era of the "-omics" sciences for interrogation of biological systems (chemical biology), and the chemical optimisation of promising small-molecules into starting points (lead molecules) for the early (pre-clinical) phase of drug discovery. The identification of new structural classes is one of the many drivers en route to innovative, safer therapeutics with novel modes of action. This is a truly daunting task given there are an estimated 10 drug-like molecules with a molecular weight below 500 Da comprised of the atoms that make up current ‘small molecule’ therapies [6]. Indeed, it would be impossible to synthesize even one molecule of each member from this set considering there is estimated to be ‘only’ 10 atoms on Earth [7]. Various strategies that attempt to address the relationship between chemistry and biology space have been developed in an effort to meet this grand challenge. One such strategy has been to compile and then screen large structurally diverse libraries that number many thousands to millions of compounds against isolated biomolecular targets (usually recombinant proteins), cell-based assays and whole organisms. The development of high-throughput screening (HTS) in the late 1980s helped achieve the goal. This was soon followed by the introduction of combinatorial chemistry in the early 1990s. These synergistic technologies, coupled with advances in genomics, revolutionised drug discovery. 4.1 Drug-like and lead-like compounds Combinatorial chemistry was attractive given its perceived promise to deliver large numbers of novel compounds in an effort to discover new chemical entities more efficiently. However, the early combinatorial chemistry libraries failed to live up to the hyperbole. Various reasons have been cited for the decline in new chemical entities recently including a move away from natural products that figured prominently in past paradigms [8]. However, a seminal analysis undertaken by Lipinski [9] identified that many combinatorial libraries were simply not comprised of “drug-like” molecules leading to the so called “Rule of 5” that identified four simple physicochemical parameter ra |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://research-repository.griffith.edu.au/bitstream/handle/10072/34922/64407_1.pdf;jsessionid=2F807782F2E9E7F7EE313CD09CE13425?sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
