archaea
Research Article | Ecological and Evolutionary ScienceMetagenomes from Coastal Marine Sediments Give Insights into the Ecological Role and Cellular Features of Loki- and ThorarchaeotaMicroorganisms of the superphylum Asgard Archaea are considered to be the closest living prokaryotic relatives of eukaryotes (including plants and animals) and thus promise to give insights into the early evolution of more complex life forms. However, very little is known about their biology as none of the organisms has yet been cultivated in the laboratory. Here we report on the ecological distribution of Asgard Archaea...
Research Article | Molecular Biology and PhysiologyThe TK0271 Protein Activates Transcription of Aromatic Amino Acid Biosynthesis Genes in the Hyperthermophilic Archaeon Thermococcus kodakarensisThe mechanisms of transcriptional regulation in archaea are still poorly understood. In this study, we identified a transcriptional regulator in the hyperthermophilic archaeon Thermococcus kodakarensis that activates the transcription of three operons involved in the biosynthesis of aromatic amino acids. The study represents one of only a few that identifies a...
Research Article | Molecular Biology and PhysiologyCell Structure Changes in the Hyperthermophilic Crenarchaeon Sulfolobus islandicus Lacking the S-LayerThe S-layer is considered to be the sole component of the cell wall in Sulfolobales, a taxonomic group within the Crenarchaeota whose cellular features have been suggested to have a close relationship to the last archaea-eukaryote common ancestor. In this study, we genetically dissect how the two previously characterized S-layer genes as well as a newly identified S-layer-associated protein-encoding gene contribute to...
Research Article | Applied and Environmental ScienceAnaerobic Degradation of Non-Methane Alkanes by “Candidatus Methanoliparia” in Hydrocarbon Seeps of the Gulf of MexicoOil-rich sediments from the Gulf of Mexico were found to contain diverse alkane-degrading groups of archaea. The symbiotic, consortium-forming “Candidatus Argoarchaeum” and “Candidatus Syntrophoarchaeum” are likely responsible for the degradation of ethane and short-chain alkanes, with the help of sulfate-reducing bacteria. “Ca. Methanoliparia” occurs as single cells associated with oil droplets. These archaea...
Research Article | Molecular Biology and PhysiologyIdentification of Dephospho-Coenzyme A (Dephospho-CoA) Kinase in Thermococcus kodakarensis and Elucidation of the Entire CoA Biosynthesis Pathway in ArchaeaCoA is utilized in a wide range of metabolic pathways, and its biosynthesis is essential for all life. Pathways for CoA biosynthesis in bacteria and eukaryotes have been established. In archaea, however, the enzyme that catalyzes the final step in CoA biosynthesis, dephospho-CoA kinase (DPCK), had not been identified. In the present study, bioinformatic analyses identified a candidate for the DPCK in archaea, which was biochemically and...
Research Article | Molecular Biology and PhysiologyPositioning of the Motility Machinery in Halophilic ArchaeaArchaea are ubiquitous single cellular microorganisms that play important ecological roles in nature. The intracellular organization of archaeal cells is among the unresolved mysteries of archaeal biology. With this work, we show that cells of haloarchaea are polarized. The cellular positioning of proteins involved in chemotaxis and motility is spatially and temporally organized in these cells. This suggests the presence of a specific...
Research Article | Host-Microbe BiologyAntimicrobial Peptides, Polymorphic Toxins, and Self-Nonself Recognition Systems in Archaea: an Untapped Armory for Intermicrobial ConflictsDiverse and highly variable systems involved in biological conflicts and self-versus-nonself discrimination are ubiquitous in bacteria but much less studied in archaea. We performed comprehensive comparative genomic analyses of the archaeal systems that share components with analogous bacterial systems and propose an approach to identify new systems that could be involved in these functions. We predict polymorphic toxin systems in 141...
Research Article | Applied and Environmental ScienceMethane-Linked Mechanisms of Electron Uptake from Cathodes by Methanosarcina barkeriMethanogenic archaea are of fundamental applied and environmental relevance. This is largely due to their activities in a wide range of anaerobic environments, generating gaseous reduced carbon that can be utilized as a fuel source. While the bioenergetics of a wide variety of methanogens have been well studied with respect to soluble substrates, a mechanistic understanding of their interaction with solid-phase redox-active compounds is...
Research Article | Molecular Biology and PhysiologyDistinct Physiological Roles of the Three Ferredoxins Encoded in the Hyperthermophilic Archaeon Thermococcus kodakarensisHigh-energy electrons liberated during catabolic processes can be exploited for energy-conserving mechanisms. Maximal energy gains demand these valuable electrons be accurately shuttled from electron donor to appropriate electron acceptor. Proteinaceous electron carriers such as ferredoxins offer opportunities to exploit specific ferredoxin partnerships to ensure that electron flux to critical physiological pathways is aligned with...