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PDBsum entry 6nxh
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Transcription/inhibitor
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PDB id
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6nxh
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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 and tailspike glycosidase machinery of orf212 from e. Coli o157:h7 phage cba120 (tsp3).
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Authors
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J.Greenfield,
X.Shang,
H.Luo,
Y.Zhou,
R.D.Heselpoth,
D.C.Nelson,
O.Herzberg.
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Ref.
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Sci Rep, 2019,
9,
7349.
[DOI no: ]
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PubMed id
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Abstract
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Bacteriophage tailspike proteins mediate virion absorption through reversible
primary receptor binding, followed by lipopolysaccharide or exopolysaccharide
degradation. The Escherichia coli O157:H7 bacteriophage CBA120 genome encodes
four distinct tailspike proteins, annotated as ORFs 210 through 213. Previously,
we reported the crystal structure of ORF210 (TSP1). Here we describe the crystal
structure of ORF212 (TSP3) determined at 1.85 Å resolution. As observed with
other tailspike proteins, TSP3 assembles into a trimer. Each subunit of TSP3 has
an N-terminal head domain that is structurally similar to that of TSP1,
consistent with their high amino acid sequence identity. In contrast, despite
sharing a β-helix fold, the overall structure of the C-terminal catalytic
domain of TSP3 is quite different when compared to TSP1. The TSP3 structure
suggests that the glycosidase active site resides in a cleft at the interface
between two adjacent subunits where three acidic residues, Glu362 and Asp383 on
one subunit, and Asp426 on a second subunit, are located in close proximity.
Comparing the glycosidase activity of wild-type TSP3 to various point mutants
revealed that catalysis requires the carboxyl groups of Glu362 and Asp426, and
not of Asp383, confirming the enzyme employs two carboxyl groups to degrade
lippopolysaccharide using an acid/base mechanism.
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