TAILIEUCHUNG - Báo cáo Y học: Modeling the three-dimensional structure of H+-ATPase of Neurospora crassa Proposal for a proton pathway from the analysis of internal cavities

Homology modeling in combination with transmembrane topology predictions are used to build the atomic model of Neurospora crassaplasmamembrane H + -ATPase, using as template the A ˚ crystal structure of rabbit sarcoplasmic reticulum Ca 2+ -ATPase [Toyoshima, C., Nakasako, M., Nomura, H. & Ogawa, H. (2000)Nature405, 647–655]. | Eur. J. Biochem. 269 5246-5258 2002 FEBS 2002 doi Modeling the three-dimensional structure of H -ATPase of Neurospora crassa Proposal for a proton pathway from the analysis of internal cavities Olivier Radresa1 Koji Ogata2 Shoshana Wodak2 Jean-Marie Ruysschaert1 and Erik Goormaghtigh1 1Service de Structure et Fonction des Membranes Biologiques Universite Libre de Bruxelles Bruxelles Belgium 2Unite de Conformation des Macromolecules Biologiques Universite Libre de Bruxelles Bruxelles Belgium Homology modeling in combination with transmembrane topology predictions are used to build the atomic model of Neurospora crassa plasma membrane H -ATPase using as template the A crystal structure of rabbit sarcoplasmic reticulum Ca2 -ATPase Toyoshima C. Nakasako M. Nomura H. Ogawa H. 2000 Nature 405 647-655 . Comparison of the two calcium-binding sites in the crystal structure of Ca2 -ATPase with the equivalent region in the H -ATPase model shows that the latter is devoid of most of the negatively charged groups required to bind the cations suggesting a different role for this region. Using the built model a pathway for proton transport is then proposed from computed locations of internal polar cavities large enough to contain at least one water molecule. As a control the same approach is applied to the high-resolution crystal structure of halorhodopsin and the proton pump bacteriorhodopsin. This revealed a striking correspondence between the positions of internal polar cavities those of crystallographic water molecules and in the case of bacteriorhodopsin the residues mediating proton translocation. In our H -ATPase model most of these cavities are in contact with residues previously shown to affect coupling of proton translocation to ATP hydrolysis. A string of six polar cavities identified in the cytoplasmic domain the most accurate part of the model suggests a proton entry path starting close to the phosphorylation site. Strikingly .

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