Complete genome sequence of Staphylothermus marinus Stetter and Fiala 1986 type strain F1

Identification and Enzymatic Analysis of an Archaeal ATP-Dependent Serine Kinase from the Hyperthermophilic Archaeon Staphylothermus marinus

Serine kinase catalyzes the phosphorylation of free serine (Ser) to produce O-phosphoserine (Sep). An ADP-dependent Ser kinase in the hyperthermophilic archaeon Thermococcus kodakarensis (Tk-SerK) is involved in cysteine (Cys) biosynthesis and most likely Ser assimilation. An ATP-dependent Ser kinase in the mesophilic bacterium Staphylococcus aureus is involved in siderophore biosynthesis. Although proteins displaying various degrees of similarity with Tk-SerK are distributed in a wide range of organisms, it is unclear if they are actually Ser kinases. Here, we examined proteins from Desulfurococcales species in Crenarchaeota that display moderate similarity with Tk-SerK from Euryarchaeota (42 to 45% identical). Tk-serK homologs from Staphylothermus marinus (Smar_0555), Desulfurococcus amylolyticus (DKAM_0858), and Desulfurococcus mucosus (Desmu_0904) were expressed in Escherichia coli. All three partially purified recombinant proteins exhibited Ser kinase activity utilizing ATP rather than ADP as a phosphate donor. Purified Smar_0555 protein displayed activity for l-Ser but not other compounds, including d-Ser, l-threonine, and l-homoserine. The enzyme utilized ATP, UTP, GTP, CTP, and the inorganic polyphosphates triphosphate and tetraphosphate as phosphate donors. Kinetic analysis indicated that the Smar_0555 protein preferred nucleoside 5'-triphosphates over triphosphate as a phosphate donor. Transcript levels and Ser kinase activity in S. marinus cells grown with or without serine suggested that the Smar_0555 gene is constitutively expressed. The genes encoding Ser kinases examined here form an operon with genes most likely responsible for the conversion between Sep and 3-phosphoglycerate of central sugar metabolism, suggesting that the ATP-dependent Ser kinases from Desulfurococcales play a role in the assimilation of Ser. IMPORTANCE Homologs of the ADP-dependent Ser kinase from the archaeon Thermococcus kodakarensis (Tk-SerK) include representatives from all three domains of life. The results of this study show that even homologs from the archaeal order Desulfurococcales, which are the most structurally related to the ADP-dependent Ser kinases from the Thermococcales, are Ser kinases that utilize ATP, and in at least some cases inorganic polyphosphates, as the phosphate donor. The differences in properties between the Desulfurococcales and Thermococcales enzymes raise the possibility that Tk-SerK homologs constitute a group of kinases that phosphorylate free serine with a wide range of phosphate donors.

Subsurface processes influence oxidant availability and chemoautotrophic hydrogen metabolism in Yellowstone hot springs

The geochemistry of hot springs and the availability of oxidants capable of supporting microbial metabolisms are influenced by subsurface processes including the separation of hydrothermal fluids into vapor and liquid phases. Here, we characterized the influence of geochemical variation and oxidant availability on the abundance, composition, and activity of hydrogen (H₂ )-dependent chemoautotrophs along the outflow channels of two-paired hot springs in Yellowstone National Park. The hydrothermal fluid at Roadside East (RSE; 82.4°C, pH 3.0) is acidic due to vapor-phase input while the fluid at Roadside West (RSW; 68.1°C, pH 7.0) is circumneutral due to liquid-phase input. Most chemotrophic communities exhibited net rates of H₂ oxidation, consistent with H₂ support of primary productivity, with one chemotrophic community exhibiting a net rate of H₂ production. Abundant H₂ -oxidizing chemoautotrophs were supported by reduction in oxygen, elemental sulfur, sulfate, and nitrate in RSW and oxygen and ferric iron in RSE; O₂ utilizing hydrogenotrophs increased in abundance down both outflow channels. Sequencing of 16S rRNA transcripts or genes from native sediments and dilution series incubations, respectively, suggests that members of the archaeal orders Sulfolobales, Desulfurococcales, and Thermoproteales are likely responsible for H₂ oxidation in RSE, whereas members of the bacterial order Thermoflexales and the archaeal order Thermoproteales are likely responsible for H₂ oxidation in RSW. These observations suggest that subsurface processes strongly influence spring chemistry and oxidant availability, which in turn select for unique assemblages of H₂ oxidizing microorganisms. Therefore, these data point to the role of oxidant availability in shaping the ecology and evolution of hydrogenotrophic organisms.

Comparative Genomics of Methanopyrus sp. SNP6 and KOL6 Revealing Genomic Regions of Plasticity Implicated in Extremely Thermophilic Profiles

Methanopyrus spp. are usually isolated from harsh niches, such as high osmotic pressure and extreme temperature. However, the molecular mechanisms for their environmental adaption are poorly understood. Archaeal species is commonly considered as primitive organism. The evolutional placement of archaea is a fundamental and intriguing scientific question. We sequenced the genomes of Methanopyrus strains SNP6 and KOL6 isolated from the Atlantic and Iceland, respectively. Comparative genomic analysis revealed genetic diversity and instability implicated in niche adaption, including a number of transporter- and integrase/transposase-related genes. Pan-genome analysis also defined the gene pool of Methanopyrus spp., in addition of ~120-Kb genomic region of plasticity impacting cognate genomic architecture. We believe that Methanopyrus genomics could facilitate efficient investigation/recognition of archaeal phylogenetic diverse patterns, as well as improve understanding of biological roles and significance of these versatile microbes.

Complete genome sequence of Staphylothermus hellenicus P8

Staphylothermus hellenicus belongs to the order Desulfurococcales within the archaeal phylum Crenarchaeota. Strain P8(T) is the type strain of the species and was isolated from a shallow hydrothermal vent system at Palaeochori Bay, Milos, Greece. It is a hyperthermophilic, anaerobic heterotroph. Here we describe the features of this organism together with the complete genome sequence and annotation. The 1,580,347 bp genome with its 1,668 protein-coding and 48 RNA genes was sequenced as part of a DOE Joint Genome Institute (JGI) Laboratory Sequencing Program (LSP) project.

Complete genome sequence of Desulfurococcus mucosus type strain (O7/1)

Desulfurococcus mucosus Zillig and Stetter 1983 is the type species of the genus Desulfurococcus, which belongs to the crenarchaeal family Desulfurococcaceae. The species is of interest because of its position in the tree of life, its ability for sulfur respiration, and several biotechnologically relevant thermostable and thermoactive extracellular enzymes. This is the third completed genome sequence of a member of the genus Desulfurococcus and already the 8(th) sequence from a member the family Desulfurococcaceae. The 1,314,639 bp long genome with its 1,371 protein-coding and 50 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.