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A Chimeric Siderophore Halts Swarming Vibrio

Authors

  • Dr. Thomas Böttcher,

    1. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115 (USA)
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  • Prof. Dr. Jon Clardy

    Corresponding author
    1. Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115 (USA)
    • Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115 (USA)===

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  • We are grateful to Jennifer Waters and the Nikon Imaging Center at the Harvard Medical School for use of the high-resolution microscope and to Dr. Shao-Liang Zheng of the Center for Crystallographic Studies, Harvard University for solving the crystal structure of avaroferrin. Image analysis and software tool development were performed at the Image and Data Analysis Core (IDAC) at Harvard Medical School with the help of Hunter Elliott. This research was supported by a Leopoldina Research Fellowship (LPDS 2009-45) of the German Academy of Sciences Leopoldina (T.B.), NIH grant GM086258 (J.C.), and NERCE-BEID through 5U54 AI057159 (J.C.).

Abstract

Some bacteria swarm under some circumstances; they move rapidly and collectively over a surface. In an effort to understand the molecular signals controlling swarming, we isolated two bacterial strains from the same red seaweed, Vibrio alginolyticus B522, a vigorous swarmer, and Shewanella algae B516, which inhibits V. alginolyticus swarming in its vicinity. Plate assays combined with NMR, MS, and X-ray diffraction analyses identified a small molecule, which was named avaroferrin, as a potent swarming inhibitor. Avaroferrin, a previously unreported cyclic dihydroxamate siderophore, is a chimera of two well-known siderophores: putrebactin and bisucaberin. The sequenced genome of S. algae revealed avaroferrin’s biosynthetic gene cluster to be a mashup of putrebactin and bisucaberin biosynthetic genes. Avaroferrin blocks swarming through its ability to bind iron in a form that cannot be pirated by V. alginolyticus, thereby securing this essential resource for its producer.

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