Structure of dimerized assimilatory NADPH-dependent sulfite reductase reveals the minimal interface for diflavin reductase binding.

ABSTRACT: Escherichia coli NADPH-dependent assimilatory sulfite reductase (SiR) reduces sulfite by six electrons to make sulfide for incorporation into sulfur-containing biomolecules. SiR has two subunits: an NADPH, FMN, and FAD-binding diflavin flavoprotein and a siroheme/Fe₄S₄ cluster-containing hemoprotein. The molecular interactions that govern subunit binding have been unknown since the discovery of SiR over 50 years ago because SiR is flexible, thus has been intransigent for traditional high-resolution structural analysis. We used a combination of the chameleon^® plunging system with a fluorinated lipid to overcome the challenges of preserving a flexible molecule to determine a 2.78 Å-resolution cryo-EM structure of a minimal heterodimer complex. chameleo

SUBMITTER: Ghazi Esfahani B 

PROVIDER: S-EPMC11195156 | biostudies-literature | 2025 Jan

REPOSITORIES: biostudies-literature