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PDBsum entry 1tht
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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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Structure of a myristoyl-Acp-Specific thioesterase from vibrio harveyi.
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Authors
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D.M.Lawson,
U.Derewenda,
L.Serre,
S.Ferri,
R.Szittner,
Y.Wei,
E.A.Meighen,
Z.S.Derewenda.
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Ref.
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Biochemistry, 1994,
33,
9382-9388.
[DOI no: ]
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PubMed id
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Abstract
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The crystal structure of a myristoyl acyl carrier protein specific thioesterase
(C14ACP-TE) from a bioluminescent bacterium, Vibrio harveyi, was solved by
multiple isomorphous replacement methods and refined to an R factor of 22% at
2.1-A resolution. This is the first elucidation of a three-dimensional structure
of a thioesterase. The overall tertiary architecture of the enzyme resembles
closely the consensus fold of the rapidly expanding superfamily of alpha/beta
hydrolases, although there is no detectable homology with any of its members at
the amino acid sequence level. Particularly striking similarity exists between
the C14ACP-TE structure and that of haloalkane dehalogenase from Xanthobacter
autotrophicus. Contrary to the conclusions of earlier studies [Ferri, S. R.,
& Meighen, E. A. (1991) J. Biol. Chem. 266, 12852-12857] which implicated
Ser77 in catalysis, the crystal structure of C14ACP-TE reveals a lipase-like
catalytic triad made up of Ser114, His241, and Asp211. Surprisingly, the
gamma-turn with Ser114 in a strained secondary conformation (phi = 53 degrees,
psi = -127 degrees), characteristic of the so-called nucleophilic elbow, does
not conform to the frequently invoked lipase/esterase consensus sequence
(Gly-X-Ser-X-Gly), as the positions of both glycines are occupied by larger
amino acids. Site-directed mutagenesis and radioactive labeling support the
catalytic function of Ser114. Crystallographic analysis of the Ser77-->Gly
mutant at 2.5-A resolution revealed no structural changes; in both cases the
loop containing the residue in position 77 is disordered.(ABSTRACT TRUNCATED AT
250 WORDS)
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