A Novel Induced-fit Reaction Mechanism of Asymmetric Hot Dog Thioesterase PaaIKunishima, N., Asada, Y., Sugahara, M., Ishijima, J., Nodake, Y., Sugahara, M., Miyano, M., Kuramitsu, S., Yokoyama, S., Sugahara, M.
(2005) J Mol Biol 352: 212-228
- PubMed: 16061252
- DOI: 10.1016/j.jmb.2005.07.008
- Primary Citation of Related Structures:
1J1Y, 1WLV, 1WLU, 1WM6, 1WN3
- PubMed Abstract:
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, crys ...
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.
Highthroughput Factory, RIKEN Harima Institute at SPring-8, 1-1-1 Kouto, Sayo-gun, Hyogo 679-5148, Japan. firstname.lastname@example.org