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PDBsum entry 3ga9
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References listed in PDB file
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Key reference
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Title
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Crystal structure of bacillus anthracis transpeptidase enzyme capd.
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Authors
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R.Wu,
S.Richter,
R.G.Zhang,
V.J.Anderson,
D.Missiakas,
A.Joachimiak.
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Ref.
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J Biol Chem, 2009,
284,
24406-24414.
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PubMed id
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Abstract
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Bacillus anthracis elaborates a poly-gamma-d-glutamic acid capsule that protects
bacilli from phagocytic killing during infection. The enzyme CapD generates
amide bonds with peptidoglycan cross-bridges to anchor capsular material within
the cell wall envelope of B. anthracis. The capsular biosynthetic pathway is
essential for virulence during anthrax infections and can be targeted for
anti-infective inhibition with small molecules. Here, we present the crystal
structures of the gamma-glutamyltranspeptidase CapD with and without
alpha-l-Glu-l-Glu dipeptide, a non-hydrolyzable analog of poly-gamma-d-glutamic
acid, in the active site. Purified CapD displays transpeptidation activity in
vitro, and its structure reveals an active site broadly accessible for
poly-gamma-glutamate binding and processing. Using structural and biochemical
information, we derive a mechanistic model for CapD catalysis whereby Pro(427),
Gly(428), and Gly(429) activate the catalytic residue of the enzyme, Thr(352),
and stabilize an oxyanion hole via main chain amide hydrogen bonds.
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