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Description of the Resource
Core applications to protein structure determination.
A principal project is to determine the three-dimensional structure of the membrane protein Vpu from HIV-1 at atomic resolution. This will bring this HIV-1 accessory protein into the realm of structural biology and make it feasible to work towards the additional goals of understanding the molecular mechanisms of it biological activities and designing drugs that interfere with these activities. It also provides an 81-residue membrane protein for structure determination, which has one hydrophobic membrane-spanning helix and a substantial cytoplasmic domain with two amphipathic in-plane helices. Polypeptides corresponding to structural and functional domains as well as full-length Vpu are expressed in bacteria. The isotopically labeled polypeptides are aligned in lipid bilayers between glass plates or magnetically aligned in bicelles by solid-state NMR spectroscopy. Significant progress has been made, as described in the initial papers.
A second principal membrane protein is the structure determination of MerF, which is part of the bacterial mercury detoxification system and transports mercury across membranes. It is expressed in bacteria for isotopic labeling and studied in bilayers and bicelles. MerF has two membrane-spanning helices. We are also studying a homologous protein, MerT, which has three membrane-spanning helices.
Filamentous bacteriophages provide a third Core system. Because they are more readily prepared and align magnetically, they are valuable model protein systems for the development of new NMR methods. Filamentous bacteriophages participate in a wide range of prokaryotic biology, and they have essential roles in many laboratory procedures of molecular biology and biotechnology, including the cloning and sequencing of DNA, and the generation and screening of peptide libraries. Although filamentous bacteriophages do not have a membrane, the major coat protein is a membrane protein in the course of the viral lifecycle because it is stored in the bacterial membrane after synthesis and processing before the assembly of new virus particles. We have determined the atomic resolution structure of fd coat protein in virus particles. In combination with the structure of the membrane-bound form of the protein in bilayers, also recently determined by solid-state NMR spectroscopy, it is possible to analyze the assembly process.Schematic diagram of
A) merF B) Vpu in lipid bilayers