1tht
|
STRUCTURE OF A MYRISTOYL-ACP-SPECIFIC THIOESTERASE FROM VIBRIO HARVEYI
OverviewOverview
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)
About this StructureAbout this Structure
1THT is a Single protein structure of sequence from Vibrio harveyi. Full crystallographic information is available from OCA.
ReferenceReference
Structure of a myristoyl-ACP-specific thioesterase from Vibrio harveyi., Lawson DM, Derewenda U, Serre L, Ferri S, Szittner R, Wei Y, Meighen EA, Derewenda ZS, Biochemistry. 1994 Aug 16;33(32):9382-8. PMID:8068614
Page seeded by OCA on Wed Nov 21 03:16:35 2007