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PDBsum entry 4tqv
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Transport protein
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PDB id
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4tqv
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Contents |
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286 a.a.
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284 a.a.
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(+ 2 more)
363 a.a.
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References listed in PDB file
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Key reference
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Title
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Structure of a bacterial abc transporter involved in the import of an acidic polysaccharide alginate.
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Authors
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Y.Maruyama,
T.Itoh,
A.Kaneko,
Y.Nishitani,
B.Mikami,
W.Hashimoto,
K.Murata.
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Ref.
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Structure, 2015,
23,
1643-1654.
[DOI no: ]
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PubMed id
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Abstract
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The acidic polysaccharide alginate represents a promising marine biomass for the
microbial production of biofuels, although the molecular and structural
characteristics of alginate transporters remain to be clarified. In
Sphingomonas sp. A1, the ATP-binding cassette transporter AlgM1M2SS is
responsible for the import of alginate across the cytoplasmic membrane. Here, we
present the substrate-transport characteristics and quaternary structure of
AlgM1M2SS. The addition of poly- or oligoalginate enhanced the ATPase activity
of reconstituted AlgM1M2SS coupled with one of the periplasmic solute-binding
proteins, AlgQ1 or AlgQ2. External fluorescence-labeled oligoalginates were
specifically imported into AlgM1M2SS-containing proteoliposomes in the presence
of AlgQ2, ATP, and Mg(2+). The crystal structure of AlgQ2-bound AlgM1M2SS adopts
an inward-facing conformation. The interaction between AlgQ2 and AlgM1M2SS
induces the formation of an alginate-binding tunnel-like structure accessible to
the solvent. The translocation route inside the transmembrane domains contains
charged residues suitable for the import of acidic saccharides.
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