6TV9

Heme d1 biosynthesis associated Protein NirF in complex with dihydro-heme d1

Summary for 6TV9

• Entry DOI: 10.2210/pdb6tv9/pdb
• Descriptor: Protein NirF,Protein NirF, HEME D (3 entities in total)
• Functional Keywords: 8-bladed beta-propeller, heme d1 biosynthesis, homodimer, ligand complex, unknown function
• Biological source: Pseudomonas aeruginosa (strain ATCC 15692 / DSM 22644 / CIP 104116 / JCM 14847 / LMG 12228 / 1C / PRS 101 / PAO1); More
• Total number of polymer chains: 8
• Total formula weight: 341694.12

Authors

Kluenemann, T.,Layer, G.,Blankenfeldt, W. (deposition date: 2020-01-09, release date: 2020-04-22, Last modification date: 2024-01-24)

Primary citation

Klunemann, T.,Nimtz, M.,Jansch, L.,Layer, G.,Blankenfeldt, W.
Crystal structure of NirF: insights into its role in heme d 1 biosynthesis.
Febs J., 288:244-261, 2021

PubMed Abstract: Certain facultative anaerobes such as the opportunistic human pathogen Pseudomonas aeruginosa can respire on nitrate, a process generally known as denitrification. This enables denitrifying bacteria to survive in anoxic environments and contributes, for example, to the formation of biofilm, hence increasing difficulties in eradicating P. aeruginosa infections. A central step in denitrification is the reduction of nitrite to nitric oxide by nitrite reductase NirS, an enzyme that requires the unique cofactor heme d . While heme d biosynthesis is mostly understood, the role of the essential periplasmatic protein NirF in this pathway remains unclear. Here, we have determined crystal structures of NirF and its complex with dihydroheme d , the last intermediate of heme d biosynthesis. We found that NirF forms a bottom-to-bottom β-propeller homodimer and confirmed this by multi-angle light and small-angle X-ray scattering. The N termini are adjacent to each other and project away from the core structure, which hints at simultaneous membrane anchoring via both N termini. Further, the complex with dihydroheme d allowed us to probe the importance of specific residues in the vicinity of the ligand binding site, revealing residues not required for binding or stability of NirF but essential for denitrification in experiments with complemented mutants of a ΔnirF strain of P. aeruginosa. Together, these data suggest that NirF possesses a yet unknown enzymatic activity and is not simply a binding protein of heme d derivatives. DATABASE: Structural data are available in PDB database under the accession numbers 6TV2 and 6TV9.

PubMed: 32255259
DOI: 10.1111/febs.15323

Experimental method

X-RAY DIFFRACTION (1.893 Å)