Fig. 5: MarDK mar1 cluster and N2ase P-cluster coordination. | Nature Catalysis

Fig. 5: MarDK mar1 cluster and N2ase P-cluster coordination.

From: Architecture, catalysis and regulation of methylthio-alkane reductase for bacterial sulfur acquisition from volatile organic compounds

Fig. 5: MarDK mar1 cluster and N2ase P-cluster coordination.

a, Cryo-EM electron density contoured at 5 sigma with 2 Å buffer around the mar1 cluster and coordinating cysteine residues. b, Same electron density contour as in (a), also showing the local MarDK protein environment. The electron density for the mar1 cluster indicates an oxidized P-like cluster with missing Fe #4. c, AlphaFold 3 model of MarDK in the mar1-cluster region, showing that the six cysteines conserved with N2ase are predicted to be positioned to coordinate a metallocofactor consistent with a reduced P-cluster (PN shown) as in N2ase. d, Structure of A. vinelandii NifDK (8CRS)71 in the P-cluster region showing PN coordination by the six conserved cysteines. In N2ase NifK Gly91 replaces MarK Cy52 (orange). e, Progressive oxidation of labile P-cluster irons of A. vinelandii NifK S188A, which is analogous to the MarK G151 residue of MAR28,29. Superscript D indicates the MarD or NifD subunit and superscript K indicates the MarK or NifK subunit.

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