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Publication Abstract from PubMed

Copper-containing nitrite reductases (CuNiRs), encoded by nirK gene, are found in all kingdoms of life with only 5% of CuNiR denitrifiers having two or more copies of nirK Recently, we have identified two copies of nirK genes in several alpha-proteobacteria of the order Rhizobiales including Bradyrhizobium sp. ORS 375, encoding a four-domain heme-CuNiR and the usual two-domain CuNiR (Br (2D)NiR). Compared with two of the best-studied two-domain CuNiRs represented by the blue (AxNiR) and green (AcNiR) subclasses, Br (2D)NiR, a blue CuNiR, shows a substantially lower catalytic efficiency despite a sequence identity of ~70%. Advanced synchrotron radiation and x-ray free-electron laser are used to obtain the most accurate (atomic resolution with unrestrained SHELX refinement) and damage-free (free from radiation-induced chemistry) structures, in as-isolated, substrate-bound, and product-bound states. This combination has shed light on the protonation states of essential catalytic residues, additional reaction intermediates, and how catalytic efficiency is modulated.

An unprecedented insight into the catalytic mechanism of copper nitrite reductase from atomic-resolution and damage-free structures.,Rose SL, Antonyuk SV, Sasaki D, Yamashita K, Hirata K, Ueno G, Ago H, Eady RR, Tosha T, Yamamoto M, Hasnain SS Sci Adv. 2021 Jan 1;7(1):eabd8523. doi: 10.1126/sciadv.abd8523. Print 2021 Jan. PMID:33523860^[1]

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