5N5F

Crystal structure of Haliangium ochraceum encapsulated ferritin

Summary for 5N5F

• Entry DOI: 10.2210/pdb5n5f/pdb
• Descriptor: encapsulated ferritin, SODIUM ION (3 entities in total)
• Functional Keywords: ferritin, encapsulin, oxidoreductase, encapsulated ferritin
• Biological source: Haliangium ochraceum
• Total number of polymer chains: 10
• Total formula weight: 115893.20

Authors

Marles-Wright, J.,He, D. (deposition date: 2017-02-13, release date: 2018-01-24, Last modification date: 2024-01-17)

Primary citation

He, D.,Piergentili, C.,Ross, J.,Tarrant, E.,Tuck, L.R.,Mackay, C.L.,McIver, Z.,Waldron, K.J.,Clarke, D.J.,Marles-Wright, J.
Conservation of the structural and functional architecture of encapsulated ferritins in bacteria and archaea.
Biochem.J., 476:975-989, 2019

PubMed Abstract: Ferritins are a large family of intracellular proteins that protect the cell from oxidative stress by catalytically converting Fe(II) into less toxic Fe(III) and storing iron minerals within their core. Encapsulated ferritins (EncFtn) are a sub-family of ferritin-like proteins, which are widely distributed in all bacterial and archaeal phyla. The recently characterized EncFtn displays an unusual structure when compared with classical ferritins, with an open decameric structure that is enzymatically active, but unable to store iron. This EncFtn must be associated with an encapsulin nanocage in order to act as an iron store. Given the wide distribution of the EncFtn family in organisms with diverse environmental niches, a question arises as to whether this unusual structure is conserved across the family. Here, we characterize EncFtn proteins from the halophile and the thermophile , which show the conserved annular pentamer of dimers topology. Key structural differences are apparent between the homologues, particularly in the centre of the ring and the secondary metal-binding site, which is not conserved across the homologues. Solution and native mass spectrometry analyses highlight that the stability of the protein quaternary structure differs between EncFtn proteins from different species. The ferroxidase activity of EncFtn proteins was confirmed, and we show that while the quaternary structure around the ferroxidase centre is distinct from classical ferritins, the ferroxidase activity is still inhibited by Zn(II). Our results highlight the common structural organization and activity of EncFtn proteins, despite diverse host environments and contexts within encapsulins.

PubMed: 30837306
DOI: 10.1042/BCJ20180922

Experimental method

X-RAY DIFFRACTION (2.057 Å)