Download MendeleyCryo-EM structure of RubisCO from Nitrosospira multiformis.
Tanaka, Y., Nishigaya, Y.(2026) Biochem Biophys Res Commun 822: 153886-153886
- PubMed: 42127514 Search on PubMed
- DOI: https://doi.org/10.1016/j.bbrc.2026.153886
- Primary Citation Related Structures:
25HN - PubMed Abstract:
Nitrosospira multiformis is a soil ammonia-oxidizing bacterium (AOB) that fixes CO 2 via RubisCO using energy derived from ammonia oxidation. Despite its ecological and agricultural relevance, the structure of N. multiformis RubisCO (NmRubisCO) remained unknown. Here, we report the cryo-EM structure of NmRubisCO at 2.26 Å resolution, determined through single-particle analysis of protein copurified with the membrane fraction following cell lysis and ultracentrifugation without column chromatography. Analysis revealed an L 8 S 8 hexadecameric Form IC (red-like) RubisCO with a six-residue insertion in the βB-βC loop (BC loop) of the large-subunit N-terminal domain that forms a solvent-exposed, well-ordered protrusion. The active site lacks carbamylation at K206 and Mg 2+ binding, representing an inactive state. A putative metal ion coordinated by H296, H298, and H331, tentatively assigned as Zn 2+ based on coordination geometry and distances, was identified near the catalytic center; this His-coordinated metal site has not been described in other RubisCO structures. Loop 6 adopts a closed-like conformation in the absence of substrate, a configuration consistent with a potential requirement for activase-mediated remodeling. The C-terminal extension of the small subunit forms interdimer β-sheet interactions that stabilize the holoenzyme. These structural features provide a framework for understanding Form IC RubisCO in carboxysome-less soil AOB.
- AgroDesign Studios, Chiba, Japan. Electronic address: tanaka@agro.design.
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