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Title 

Substrate binding mechanism of a type I extradiol dioxygenase

Authors 

H J ChoK KimS Y SohnH Y ChoK J KimMyung Hee KimD KimE KimB S Kang

Publisher 

American Society for Biochemistry and Molecular Biology

Issue Date 

2010

Citation 

Journal of Biological Chemistry, vol. 285, no. 45, pp. 34643-34652

Keywords 

Active siteAerobic degradationC-domainC-terminal tailCoordination sitesDioxygenasesDioxygensEnzyme substratesExtradiolHairpin structuresHydroxyl groupsIntermediate stageMeta-cleavage pathwayStructural elementsStructure-basedSubstrate bindingSubstrate specificitySubstrate-binding mechanismSubstrate-boundTwo-step mechanisms

Abstract 

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 β-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 β-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.

ISSN 

0021-9258

Link 

http://dx.doi.org/10.1074/jbc.M110.130310

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2017-04-19


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