A Caltech Library Service

A Reduced F₄₂₀-Dependent Nitrite Reductase in an Anaerobic Methanotrophic Archaeon

Heryakusuma, Christian and Susanti, Dwi and Yu, Hang and Li, Zhou and Purwantini, Endang and Hettich, Robert L. and Orphan, Victoria J. and Mukhopadhyay, Biswarup (2022) A Reduced F₄₂₀-Dependent Nitrite Reductase in an Anaerobic Methanotrophic Archaeon. Journal of Bacteriology, 204 (7). Art. No. e00078-22. ISSN 0021-9193. PMCID PMC9295563. doi:10.1128/jb.00078-22.

[img] PDF - Published Version
Creative Commons Attribution.

[img] PDF (Supplemental Material) - Supplemental Material
Creative Commons Attribution.


Use this Persistent URL to link to this item:


Anaerobic methanotrophic archaea (ANME), which oxidize methane in marine sediments through syntrophic associations with sulfate-reducing bacteria, carry homologs of coenzyme F₄₂₀-dependent sulfite reductase (Fsr) of Methanocaldococcus jannaschii, a hyperthermophilic methanogen from deep-sea hydrothermal vents. M. jannaschii Fsr (MjFsr) and ANME-Fsr belong to two phylogenetically distinct groups, FsrI and FsrII, respectively. MjFsrI reduces sulfite to sulfide with reduced F₄₂₀ (F₄₂₀H₂), protecting methyl coenzyme M reductase (Mcr), an essential enzyme for methanogens, from sulfite inhibition. However, the function of FsrIIs in ANME, which also rely on Mcr and live in sulfidic environments, is unknown. We have determined the catalytic properties of FsrII from a member of ANME-2c. Since ANME remain to be isolated, we expressed ANME2c-FsrII in a closely related methanogen, Methanosarcina acetivorans. Purified recombinant FsrII contained siroheme, indicating that the methanogen, which lacks a native sulfite reductase, produced this coenzyme. Unexpectedly, FsrII could not reduce sulfite or thiosulfate with F₄₂₀H₂. Instead, it acted as an F₄₂₀H₂-dependent nitrite reductase (FNiR) with physiologically relevant Km values (nitrite, 5 μM; F₄₂₀H₂, 14 μM). From kinetic, thermodynamic, and structural analyses, we hypothesize that in FNiR, F₄₂₀H₂-derived electrons are delivered at the oxyanion reduction site at a redox potential that is suitable for reducing nitrite (E⁰′ [standard potential], +440 mV) but not sulfite (E⁰′, −116 mV). These findings and the known nitrite sensitivity of Mcr suggest that FNiR may protect nondenitrifying ANME from nitrite toxicity. Remarkably, by reorganizing the reductant processing system, Fsr transforms two analogous oxyanions in two distinct archaeal lineages with different physiologies and ecologies.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Yu, Hang0000-0002-7600-1582
Orphan, Victoria J.0000-0002-5374-6178
Additional Information:© 2022 Heryakusuma et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Received: 28 February 2022. Accepted: 24 May 2022. Published online: 13 June 2022. We thank William W. Metcalf of the University of Illinois at Urbana-Champaign and his laboratory members for providing Methanosarcina acetivorans strains, plasmids, and protocols that have been used in the study for the heterologous expression of FNiR. We also thank Kylie Allen of the Virginia Tech Department of Biochemistry for critically reading the manuscript. This work was supported by National Aeronautics and Space Administration Astrobiology: Exobiology and Evolutionary Biology grant NNX13AI05G to B.M. and the Virginia Tech Agricultural Experiment Station Hatch Program (CRIS project VA-160021). C.H. was supported with a fellowship from the Genetics, Bioinformatics, and Computational Biology Ph.D. Program of the Virginia Tech. This work was also supported in part by a grant from the Gordon and Betty Moore Foundation Marine Symbiosis program (GBMF grant 9324) and the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research, award number DE-SC0020373 to V.J.O.
Funding AgencyGrant Number
Virginia TechVA-160021
Gordon and Betty Moore FoundationGBMF 9324
Department of Energy (DOE)DE-SC0020373
Issue or Number:7
PubMed Central ID:PMC9295563
Record Number:CaltechAUTHORS:20220715-744227000
Persistent URL:
Official Citation:Heryakusuma C, Susanti D, Yu H, et al. A Reduced F420-Dependent Nitrite Reductase in an Anaerobic Methanotrophic Archaeon. J Bacteriol. 2022;204(7):e0007822. doi:10.1128/jb.00078-22
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115644
Deposited By: George Porter
Deposited On:21 Jul 2022 16:30
Last Modified:21 Jul 2022 16:30

Repository Staff Only: item control page