Transport of Nitrate and Nitrite across Cell Membranes
Final Report Abstract
Enteric bacteria such as Salmonella evade the immune defense of their human hosts by proliferating inside the immune cells – macrophages – themselves, thereby levering out this particular defense mechanism and at the same time hiding from other actors of the immune system. One of the methods to successfully avoid damage through macrophage is to counter their potent cytotoxin peroxynitrite by uptake into the bacterial cell and subsequent reduction to harmless products. To this end, Salmonella was suggested to employ the NirC protein, an integral membrane protein that normally imports the nitrite anion, NO2–, for cytoplasmic reduction to ammonia, a crucial building block of all biomacromolecules. We had already obtained a three-dimensional structure of NirC from Salmonella typhimurium by X-ray crystallography and had characterized the passive transport of nitrite by planar lipid bilayer electrophysiology. In the present project we set out to test the hypothesis of peroxynitrite uptake, to further characterize the NirC protein and some of its evolutionary relatives and to identify novel compounds that can act as specific inhibitors for NirC-mediated anion uptake. Constituting an important defense mechanism against host immunity, the deletion of NirC had previously been shown to decrease the pathogenicity of Salmonella, from which we concluded that specific inhibitors for NirC have a high potential to become a new, potent class of antimicrobial agents.
Publications
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(2013) The FNT Family of Anion Channels. Biol. Chem. 394, 715-727
Lü, W., Du, J., Schwarzer, N., Wacker, T., Andrade, S.L.A. & Einsle, O.
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(2013) The Tricky Task of Nitrate/Nitrite Antiport. Angew. Chem. Intl. Ed., 52, 10422-10424
Andrade, S.L.A. & Einsle, O.
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(2014) Direct Observation of Electrogenic NH4+ Transport in Ammonium Transport (Amt) Proteins, Proc. Natl. Acad. Sci. USA, 111, 9995-10000
Wacker T., Garcia-Celma J., Lewe P. and Andrade S.L.A.
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(2015) Structural and functional studies of NirC from Salmonella typhimurium. Meth. Enzymol., 556, 475-497
Rycovska-Blume, A., Lü, W., Andrade, S., Fendler, K. & Einsle, O.
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(2016) 4-acyl pyrrole derivatives yield novel vectors for designing inhibitors of the acetyl-lysine recognition site of BRD4(1). J. Med. Chem., 59, 1518-1530
Hügle, M., Lucas, X., Weitzel, G., Ostrovskyi, D., Breit, B., Gerhardt, S., Einsle, O., Günther, S. & Wohlwend, D.
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(2016) Channels and Transporters for Nitrogen Cycle Intermediates, In: Metalloenzymes in Denitrification: Applications and Environmental Impacts. (Moura, I., Moura, J.J.G., Pauleta, S.R. & Maia, L., eds.), RSC Publishing, Oxford, 287-311
Andrade, S.L.A. & Einsle, O.
