6TSI

cd1 nitrite reductase NirS with bound dihydro-heme d1

Summary for 6TSI

• Entry DOI: 10.2210/pdb6tsi/pdb
• Descriptor: Nitrite reductase, HEME C, HEME D, ... (6 entities in total)
• Functional Keywords: cd1 nitrite reductase, nirs, oxidoreductase
• Biological source: Pseudomonas aeruginosa PAO1
• Total number of polymer chains: 2
• Total formula weight: 123832.20

Authors

Kluenemann, T.,Blankenfeldt, W. (deposition date: 2019-12-20, release date: 2020-11-18, Last modification date: 2024-11-13)

Primary citation

Klunemann, T.,Blankenfeldt, W.
Structure of heme d 1 -free cd 1 nitrite reductase NirS.
Acta Crystallogr.,Sect.F, 76:250-256, 2020

PubMed Abstract: A key step in anaerobic nitrate respiration is the reduction of nitrite to nitric oxide, which is catalysed by the cd nitrite reductase NirS in, for example, the Gram-negative opportunistic pathogen Pseudomonas aeruginosa. Each subunit of this homodimeric enzyme consists of a cytochrome c domain and an eight-bladed β-propeller that binds the uncommon isobacteriochlorin heme d as an essential part of its active site. Although NirS has been well studied mechanistically and structurally, the focus of previous studies has been on the active heme d-bound form. The heme d-free form of NirS reported here, which represents a premature state of the reductase, adopts an open conformation with the cytochrome c domains moved away from each other with respect to the active enzyme. Further, the movement of a loop around Trp498 seems to be related to a widening of the propeller, allowing easier access to the heme d-binding side. Finally, a possible link between the open conformation of NirS and flagella formation in P. aeruginosa is discussed.

PubMed: 32510465
DOI: 10.1107/S2053230X20006676

Experimental method

X-RAY DIFFRACTION (2.38 Å)