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Heme uptake across the outer membrane as revealed by crystal structures of the receptor-hemophore complex.

Abstract : Gram-negative bacteria use specific heme uptake systems, relying on outer membrane receptors and excreted heme-binding proteins (hemophores) to scavenge and actively transport heme. To unravel the unknown molecular details involved, we present 3 structures of the Serratia marcescens receptor HasR in complex with its hemophore HasA. The transfer of heme over a distance of 9 A from its high-affinity site in HasA into a site of lower affinity in HasR is coupled with the exergonic complex formation of the 2 proteins. Upon docking to the receptor, 1 of the 2 axial heme coordinations of the hemophore is initially broken, but the position and orientation of the heme is preserved. Subsequently, steric displacement of heme by a receptor residue ruptures the other axial coordination, leading to heme transfer into the receptor.
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https://hal-pasteur.archives-ouvertes.fr/pasteur-00366353
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Submitted on : Friday, March 6, 2009 - 3:43:11 PM
Last modification on : Monday, January 13, 2020 - 5:08:08 PM

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Stefanie Krieg, Frédéric Huché, Kay Diederichs, Nadia Izadi-Pruneyre, Anne Lecroisey, et al.. Heme uptake across the outer membrane as revealed by crystal structures of the receptor-hemophore complex.. Proceedings of the National Academy of Sciences of the United States of America , National Academy of Sciences, 2009, 106 (4), pp.1045-50. ⟨10.1073/pnas.0809406106⟩. ⟨pasteur-00366353⟩

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