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PDBsum entry 1or0
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Contents |
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* Residue conservation analysis
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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 structures of glutaryl 7-Aminocephalosporanic acid acylase: insight into autoproteolytic activation.
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Authors
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J.K.Kim,
I.S.Yang,
S.Rhee,
Z.Dauter,
Y.S.Lee,
S.S.Park,
K.H.Kim.
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Ref.
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Biochemistry, 2003,
42,
4084-4093.
[DOI no: ]
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PubMed id
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Abstract
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Glutaryl 7-aminocephalosporanic acid acylase (GCA, EC 3.5.1.11) is a member of
N-terminal nucleophile (Ntn) hydrolases. The native enzyme is an (alpha beta)(2)
heterotetramer originated from an enzymatically inactive precursor of a single
polypeptide. The activation of precursor GCA consists of primary and secondary
autoproteolytic cleavages, generating a terminal residue with both a nucleophile
and a base and releasing a nine amino acid spacer peptide. We have determined
the crystal structures of the recombinant selenomethionyl native and S170A
mutant precursor from Pseudomonas sp. strain GK16. Precursor activation is
likely triggered by conformational constraints within the spacer peptide,
probably inducing a peptide flip. Autoproteolytic site solvent molecules, which
have been trapped in a hydrophobic environment by the spacer peptide, may play a
role as a general base for nucleophilic attack. The activation results in
building up a catalytic triad composed of Ser170/His192/Glu624. However, the
triad is not linked to the usual hydroxyl but the free alpha-amino group of the
N-terminal serine residue of the native GCA. Mutagenesis and structural data
support the notion that the stabilization of a transient hydroxazolidine ring
during autoproteolysis would be critical during the N --> O acyl shift. The
autoproteolytic activation mechanism for GCA is described.
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