1j1y

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spinqualitylabelsall models 1j1y, resolution 1.7Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal Structure of PaaI from Thermus thermophilus HB8

Overview

Hot dog fold proteins sharing the characteristic "hot dog" fold are known, to involve certain coenzyme A binding enzymes with various oligomeric, states. In order to elucidate the oligomerization-function relationship of, the hot dog fold proteins, crystal structures of the phenylacetate, degradation protein PaaI from Thermus thermophilus HB8 (TtPaaI), a, tetrameric acyl-CoA thioesterase with the hot dog fold, have been, determined and compared with those of other family members. In the, liganded crystal forms with coenzyme A derivatives, only two of four, intersubunit catalytic pockets of the TtPaaI tetramer are occupied by the, ligands. A detailed structural comparison between several liganded and, unliganded forms reveals that a subtle rigid-body rearrangement of, subunits within 2 degrees upon binding of the first two ligand molecules, can induce a strict negative cooperativity to prevent further binding at, the remaining two pockets, indicating that the so-called, "half-of-the-sites reactivity" of oligomeric enzymes is visualized for the, first time. Considering kinetic and mutational analyses together, a, possible reaction mechanism of TtPaaI is proposed; one tetramer binds only, two acyl-CoA molecules with a novel asymmetric induced-fit mechanism and, carries out the hydrolysis according to a base-catalyzed reaction through, activation of a water molecule by Asp48. From a structural comparison with, other family members, it is concluded that a subgroup of the hot dog fold, protein family, referred to as "asymmetric hot dog thioesterases", including medium chain acyl-CoA thioesterase II from Escherichia coli and, human thioesterase III, might share the same oligomerization mode and the, asymmetric induced-fit mechanism as observed in TtPaaI.

About this Structure

1J1Y is a Single protein structure of sequence from Thermus thermophilus with CL and MG as ligands. Full crystallographic information is available from OCA.

Reference

A novel induced-fit reaction mechanism of asymmetric hot dog thioesterase PAAI., Kunishima N, Asada Y, Sugahara M, Ishijima J, Nodake Y, Sugahara M, Miyano M, Kuramitsu S, Yokoyama S, Sugahara M, J Mol Biol. 2005 Sep 9;352(1):212-28. PMID:16061252

Page seeded by OCA on Sat Nov 24 22:56:27 2007