Comparative Genomics and Proteomic Analysis of Assimilatory Sulfate Reduction Pathways in Anaerobic Methanotrophic Archaea

Hang Yu, Dwi Susanti, Shawn E. McGlynn, Connor T. Skennerton, Karuna Chourey, Ramsunder Iyer, Silvan Scheller, Patricia L. Tavormina, Robert L. Hettich, Biswarup Mukhopadhyay, Victoria J. Orphan

Research output: Contribution to journalArticleScientificpeer-review


Sulfate is the predominant electron acceptor for anaerobic oxidationof methane (AOM) in marine sediments. This process is carried out by a syntrophic consortium of anaerobic methanotrophic archaea (ANME) and sulfate reducing bacteria (SRB) through an energy conservation mechanism that is still poorly understood. It was previously hypothesized that ANME alone could couple methane oxidation to dissimilatory sulfate reduction, but a genetic and biochemical basis for this proposal has not been identified. Using comparative genomic and phylogenetic analyses, we found the genetic capacity in ANME and related methanogenic archaea for sulfate reduction, including sulfate adenylyltransferase, APS kinase, APS/PAPS reductase and two different sulfite reductases. Based on characterized homologs and the lack of associated energy conserving complexes, the sulfate reduction pathways in ANME are likely used for assimilation but not dissimilation of sulfate. Environmental metaproteomic analysis confirmed the expression of 6 proteins in the sulfate assimilation pathway of ANME. The highest expressed proteins related to sulfate assimilation were two sulfite reductases, namely assimilatory-type low-molecular-weight sulfite reductase (alSir) and a divergent group of coenzyme F420-dependent sulfite reductase (Group II Fsr). In methane seep sediment microcosm experiments, however, sulfite and zero-valent sulfur amendments were inhibitory to ANME-2a/2c while growth in their syntrophic SRB partner was not observed. Combined with our genomic and metaproteomic results, the passage of sulfur species by ANME as metabolic intermediates for their SRB partners is unlikely. Instead, our findings point to a possible niche for ANME to assimilate inorganic sulfur compounds more oxidized than sulfide in anoxic marine environments.
Original languageEnglish
Article number2917
Number of pages15
JournalFrontiers in Microbiology
Early online date3 Dec 2018
Publication statusPublished - Dec 2018
MoE publication typeA1 Journal article-refereed


  • sulfur pathway
  • sulfate reduction
  • anaerobic oxidation of methane
  • ANME
  • syntrophy
  • sulfate adenylyltransferase
  • APS/PAPS Reductase
  • sulfite reductase


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