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Structure of Escherichia coli Flavodiiron Nitric Oxide Reductase

DOI: 10.1016/j.jmb.2016.10.008 DOI Help

Authors: Célia V. Romão (Instituto de Tecnologia Química e Biológica António Xavier) , João B. Vicente (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Patricia Borges (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Bruno L. Victor (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Pedro Lamosa (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Elísio Silva (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Luís Pereira (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Tiago M. Bandeiras (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA; Instituto de Biologia Experimental e Tecnológica) , Cláudio M. Soares (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Maria A. Carrondo (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , David Turner (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Miguel Teixeira (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA) , Carlos Frazao (Instituto de Tecnologia Química e Biológica António Xavier, ITQB NOVA)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of Molecular Biology , VOL 428 , PAGES 4686 - 4707

State: Published (Approved)
Published: November 2016

Abstract: Flavodiiron proteins (FDPs) are present in organisms from all domains of life and have been described so far to be involved in the detoxification of oxygen or nitric oxide (NO), acting as O2 and/or NO reductases. The Escherichia coli FDP, named flavorubredoxin (FlRd), is the most extensively studied FDP. Biochemical and in vivo studies revealed that FlRd is involved in NO detoxification as part of the bacterial defense mechanisms against reactive nitrogen species. E. coli FlRd has a clear preference for NO as a substrate in vitro, exhibiting a very low reactivity toward O2. To contribute to the understanding of the structural features defining this substrate selectivity, we determined the crystallographic structure of E. coli FlRd, both in the isolated and reduced states. The overall tetrameric structure revealed a highly conserved flavodiiron core domain, with a metallo-β-lactamase-like domain containing a diiron center, and a flavodoxin domain with a flavin mononucleotide cofactor. The metal center in the oxidized state has a μ-hydroxo bridge coordinating the two irons, while in the reduced state, this moiety is not detected. Since only the flavodiiron domain was observed in these crystal structures, the structure of the rubredoxin domain was determined by NMR. Tunnels for the substrates were identified, and through molecular dynamics simulations, no differences for O2 or NO permeation were found. The present data represent the first structure for a NO-selective FDP.

Journal Keywords: flavorubredoxin; flavodiiron protein; NorV; diiron center; nitric oxide

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I04-Macromolecular Crystallography

Other Facilities: European Synchrotron Research Facility