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PDBsum entry 2adv
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Contents |
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161 a.a.
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28 a.a.
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494 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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Insight into autoproteolytic activation from the structure of cephalosporin acylase: a protein with two proteolytic chemistries.
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Authors
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J.K.Kim,
I.S.Yang,
H.J.Shin,
K.J.Cho,
E.K.Ryu,
S.H.Kim,
S.S.Park,
K.H.Kim.
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Ref.
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Proc Natl Acad Sci U S A, 2006,
103,
1732-1737.
[DOI no: ]
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PubMed id
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Abstract
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Cephalosporin acylase (CA), a member of the N-terminal nucleophile hydrolase
family, is activated through sequential primary and secondary autoproteolytic
reactions with the release of a pro segment. We have determined crystal
structures of four CA mutants. Two mutants are trapped after the primary
cleavage, and the other two undergo secondary cleavage slowly. These structures
provide a look at pro-segment conformation during activation in N-terminal
nucleophile hydrolases. The highly strained helical pro segment of precursor is
transformed into a relaxed loop in the intermediates, suggesting that the
relaxation of structural constraints drives the primary cleavage reaction. The
secondary autoproteolytic step has been proposed to be intermolecular. However,
our analysis provides evidence that CA is processed in two sequential steps of
intramolecular autoproteolysis involving two distinct residues in the active
site, the first a serine and the second a glutamate.
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Figure 2.
Structural comparison of CA proteins. (A) Superposition of
the overall structures of S170A, S170C, E159Q, Y202L, R226K, and
the mature CA. Each structure is shown in yellow, cyan, dark
green, green, slate blue, and marine, respectively. To emphasize
the differences of the pro segments, the pro segment of Y202L is
shown in red. Residues Gly-160, Ser-170, Tyr-202, and Arg-226
are shown in a ball-and-stick representation in magenta. (B)
Stereoview of the pro-segment conformation of Y202L. The
electron density map corresponds to the 2 F [o] − F [c] map
calculated at 0.5 σ.
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Figure 3.
Secondary autocleavage site of CA proteins. The interactions
between pro-segment and protein residues in Y202L, precursor
S170A, R226K, S170C, and E159Q. Those involved in hydrophobic
interactions in S170A are superimposed in a transparent
space-filling representation. Hydrogen bonds are indicated by
dotted lines, and water molecules are represented as red
spheres. The distances between the side chain of Glu-159 and the
backbone carbon atom of Gly-160 via WAT1 in Y202L and R226K are
highlighted by thick dotted lines.
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