2wl9

Publication Abstract from PubMed

A meta-cleavage pathway for the aerobic degradation of aromatic hydrocarbons is catalyzed by extradiol dioxygenases via a two-step mechanism: catechol substrate binding and dioxygen incorporation. The binding of substrate triggers the release of water, thereby opening a coordination site for molecular oxygen. The crystal structures of AkbC, a type I extradiol dioxygenase, and the enzyme-substrate (3-methylcatechol) complex revealed the substrate-binding process of extradiol dioxygenase. AkbC is composed of an N-domain and an active C-domain, which contains iron coordinated by a 2-His-1-carboxylate facial triad motif. The C-domain includes a beta-hairpin structure and a C-terminal tail. In substrate-bound AkbC, 3-methylcatechol interacts with the iron via a single hydroxyl group, which represents an intermediate stage in the substrate-binding process. Structure-based mutagenesis revealed that the C-terminal tail and beta-hairpin form part of the substrate-binding pocket that is responsible for substrate specificity by blocking substrate entry. Once a substrate enters the active site, these structural elements also play a role in the correct positioning of the substrate. Based on the results presented here, a putative substrate-binding mechanism is proposed.

Substrate-binding mechanism of a type I extradiol dioxygenase.,Cho HJ, Kim K, Sohn SY, Cho HY, Kim KJ, Kim MH, Kim D, Kim E, Kang BS J Biol Chem. 2010 Sep 1. PMID:20810655^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.