9WT8

Crystal structure of a multiheme cytochrome c selenoprotein (MccSep)

Summary for 9WT8

• Entry DOI: 10.2210/pdb9wt8/pdb
• Descriptor: Cytochrome c,Multiheme cytochrome c selenoprotein (MccSep), HEME C, SULFATE ION, ... (7 entities in total)
• Functional Keywords: multiheme, cytochrome c, selenoprotein, electron transport
• Biological source: Geobacter sulfurreducens PCA; More
• Total number of polymer chains: 4
• Total formula weight: 220389.41

Authors

Mihara, H.,Yoshizawa, T.,Izu, Y.,Inoue, M.,Aono, R.,Zhang, W.,Shibamoto, N.,Tobe, R.,Kurihara, T.,Matsumura, H. (deposition date: 2025-09-16, release date: 2026-07-22, Last modification date: 2026-09-16)

Primary citation

Mihara, H.,Yoshizawa, T.,Izu, Y.,Zhang, W.,Inoue, M.,Shimamoto, N.,Tobe, R.,Aono, R.,Kurihara, T.,Matsumura, H.
Multiheme selenoenzyme essential for elemental sulfur respiration.
Sci Adv, 12:eaeg2218-eaeg2218, 2026

PubMed Abstract: Elemental sulfur reduction is a key process in anaerobic ecosystems and the global sulfur cycle. Although elemental sulfur serves as a terminal electron acceptor in microbial respiration, the molecular basis is unclear. Here, we identify a conserved multiheme cytochrome selenoprotein essential for sulfur reduction in a sulfur-respiring bacterium. Structural and biochemical analyses show that the enzyme forms a tetramer, with each subunit containing five hemes and one selenocysteine residue. The enzyme catalyzes polysulfide reduction at an active site, where a cysteine coordinates the heme iron, while selenocysteine is essential for catalysis. Genetic analyses show that both residues are critical for sulfur respiration in vivo. These findings reveal a selenium-sulfur-dependent catalysis on a heme center for polysulfide reduction, expanding our understanding of microbial energy metabolism.

PubMed: 42647610
DOI: 10.1126/sciadv.aeg2218

Experimental method

X-RAY DIFFRACTION (1.75 Å)