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Structures of substrate- and product-bound forms of a multi-domain copper nitrite reductase shed light on the role of domain tethering in protein complexes

DOI: 10.1107/S2052252520005230 DOI Help

Authors: Daisuke Sasaki (University of Liverpool) , Tatiana F. Watanabe (University of Liverpool; University of São Paulo) , Robert R. Eady (University of Liverpool) , Richard C. Garratt (University of São Paulo) , Svetlana V. Antonyuk (University of Liverpool) , S. Samar Hasnain (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Iucrj , VOL 7 , PAGES 557 - 565

State: Published (Approved)
Published: May 2020
Diamond Proposal Number(s): 15991

Open Access Open Access

Abstract: Copper-containing nitrite reductases (CuNiRs) are found in all three kingdoms of life and play a major role in the denitrification branch of the global nitro­gen cycle where nitrate is used in place of di­oxy­gen as an electron acceptor in respiratory energy metabolism. Several C- and N-terminal redox domain tethered CuNiRs have been identified and structurally characterized during the last decade. Our understanding of the role of tethered domains in these new classes of three-domain CuNiRs, where an extra cytochrome or cupredoxin domain is tethered to the catalytic two-domain CuNiRs, has remained limited. This is further compounded by a complete lack of substrate-bound structures for these tethered CuNiRs. There is still no substrate-bound structure for any of the as-isolated wild-type tethered enzymes. Here, structures of nitrite and product-bound states from a nitrite-soaked crystal of the N-terminal cupredoxin-tethered enzyme from the Hyphomicrobium denitrificans strain 1NES1 (Hd1NES1NiR) are provided. These, together with the as-isolated structure of the same species, provide clear evidence for the role of the N-terminal peptide bearing the conserved His27 in water-mediated anchoring of the substrate at the catalytic T2Cu site. Our data indicate a more complex role of tethering.

Journal Keywords: nitro­gen cycle; denitrification; copper-containing nitrite reductase; electron transfer; catalysis; structural biology

Subject Areas: Biology and Bio-materials

Instruments: I04-Macromolecular Crystallography