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PDBsum entry 3lhs
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Transport protein
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PDB id
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3lhs
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References listed in PDB file
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Key reference
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Title
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The staphylococcus aureus siderophore receptor htsa undergoes localized conformational changes to enclose staphyloferrin a in an arginine-Rich binding pocket.
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Authors
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J.C.Grigg,
J.D.Cooper,
J.Cheung,
D.E.Heinrichs,
M.E.Murphy.
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Ref.
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J Biol Chem, 2010,
285,
11162-11171.
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PubMed id
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Abstract
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Staphylococcus aureus uses several efficient iron acquisition strategies to
overcome iron limitation. Recently, the genetic locus encoding biosynthetic
enzymes for the iron chelating molecule, staphyloferrin A (SA), was determined.
S. aureus synthesizes and secretes SA into its environment to scavenge iron. The
membrane-anchored ATP binding cassette-binding protein, HtsA, receives the
ferric-chelate for import into the cell. Recently, we determined the apoHtsA
crystal structure, the first siderophore receptor from gram-positive bacteria to
be structurally characterized. Herein we present the x-ray crystal structure of
the HtsA-ferric-SA complex. HtsA adopts a class III binding protein fold
composed of separate N- and C-terminal domains bridged by a single alpha-helix.
Recombinant HtsA can efficiently sequester ferric-SA from S. aureus culture
supernatants where it is bound within the pocket formed between distinct N- and
C-terminal domains. A basic patch composed mainly of six Arg residues contact
the negatively charged siderophore, securing it within the pocket. The x-ray
crystal structures from two different ligand-bound crystal forms were
determined. The structures represent the first structural characterization of an
endogenous alpha-hydroxycarboxylate-type siderophore-receptor complex. One
structure is in an open form similar to apoHtsA, whereas the other is in a more
closed conformation. The conformational change is highlighted by isolated
movement of three loops within the C-terminal domain, a domain movement unique
to known class III binding protein structures.
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