Nature Structural Biology
6, 516 - 520 (1999)
doi:10.1038/9281
The crystal structure of HasA, a hemophore secreted by Serratia marcescensPascal Arnoux1, Richard Haser2, Nadia Izadi3, Anne Lecroisey3, Muriel Delepierre3, Cécile Wandersman4
& Mirjam Czjzek11
Laboratoire d'Architecture et Fonction des Macromolécules Biologiques UPR 9039, Institut de Biologie Structurale et Microbiologie, CNRS, 31, chemin Joseph Aiguier, 13402 Marseille Cedex 20, France. 2
Institut de Biologie et Chimie des Protéines, CNRS, 7 passage du Vercors, 69367 Lyon Cedex 07, France. 3
Laboratoire de Résonance Magnétique Nucléaire, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 20, France. 4
Unité de Physiologie Cellulaire, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 20, France.
Correspondence should be addressed to Mirjam Czjzek czjzek@afmb.cnrs−mrs.frFree iron availability is strongly limited in vertebrate hosts, making the iron acquisition by siderophores inappropriate. Pathogenic bacteria have developed various ways to use the host's iron from iron-containing proteins. Serratia marcescens can use the iron from hemoglobin through the secretion of a hemophore called HasA, which takes up the heme from hemoglobin and shuttles it to the receptor HasR, which in turn, releases heme into the bacterium. We report here the first crystal structure of such a hemophore, bound to a heme group at two different pH values and at a resolution of 1.9 Å. The structure reveals a new original fold and suggests a hypothetical mechanism for both heme uptake and release.
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