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

IUCrJ

Daisuke Sasaki¹  S. Samar Hasnain¹  Robert R. Eady¹  Svetlana V. Antonyuk¹  Tatiana F. Watanabe¹  Richard C. Garratt² 

[1] Molecular Biophysics Group, Institute of Systems, Molecular and Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom;The São Carlos Institute of Physics, University of São Paulo, São Carlos 13563-120, Brazil;

关键词: nitrogen cycle;    denitrification;    copper-containing nitrite reductase;    electron transfer;    catalysis;    structural biology;   

DOI  :  10.1107/S2052252520005230

来源: DOAJ

【 摘 要 】

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 than the intuitive advantage for a partner-protein electron-transfer complex by narrowing the conformational search in such a combined system.

【 授权许可】

Unknown