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Updated: May 28, 2025

Co-Translational Insertion of Membrane Proteins into Preformed Nanodiscs
Published on: November 19, 2020
Insertion of the FeB cofactor in cNORs lacking metal inserting chaperones
Sofia Appelgren1, Pia Ädelroth1
1Department of Biochemistry and Biophysics, Stockholm University, Sweden.
Abstract:
Cytochrome c-dependent nitric oxide reductase (cNOR) catalyzes the reduction of NO into nitrous oxide (N2O), a strong greenhouse gas released from denitrifying microorganisms. The cNOR active site holds an essential non-heme iron, FeB, inserted using the chaperone complex NorQD. However, in Thermus thermophilus, the cNOR (TtcNOR) cluster lacks the norQD genes. Here we investigated FeB insertion into TtcNOR and characterized and compared TtcNOR expressed in Escherichia coli to that natively produced. We show that FeB is present in the natively produced TtcNOR only. Analysis of cNOR operon sequences suggests that a hydrophilic K-pathway analogue is present in cNORs that do not rely on NorQD for iron insertion. We discuss the implications of our data for the evolution of the NOR family.
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