Thermococcus bergensis sp. nov., a Novel Hyperthermophilic Starch-Degrading Archaeon.
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ABSTRACT:
SUBMITTER: Birkeland NK
PROVIDER: S-EPMC8146568 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:UnlabelledA structurally novel chitinase, Tc-ChiD, was identified from the hyperthermophilic archaeon Thermococcus chitonophagus, which can grow on chitin as the sole organic carbon source. The gene encoding Tc-ChiD contains regions corresponding to a signal sequence, two chitin-binding domains, and a putative catalytic domain. This catalytic domain shows no similarity with previously characterized chitinases but resembles an uncharacterized protein found in the mesophilic anaerobic bacterium Clostridium botulinum Two recombinant Tc-ChiD proteins were produced in Escherichia coli, one without the signal sequence [Tc-ChiD(ΔS)] and the other corresponding only to the putative catalytic domain [Tc-ChiD(ΔBD)]. Enzyme assays using N-acetylglucosamine (GlcNAc) oligomers indicated that both proteins hydrolyze GlcNAc oligomers longer than (GlcNAc)4 Chitinase assays using colloidal chitin suggested that Tc-ChiD is an exo-type chitinase that releases (GlcNAc)2 or (GlcNAc)3 Analysis with GlcNAc oligomers modified with p-nitrophenol suggested that Tc-ChiD recognizes the reducing end of chitin chains. While Tc-ChiD(ΔBD) displayed a higher initial velocity than that of Tc-ChiD(ΔS), we found that the presence of the two chitin-binding domains significantly enhanced the thermostability of the catalytic domain. In T. chitonophagus, another chitinase ortholog that is similar to the Thermococcus kodakarensis chitinase ChiA is present and can degrade chitin from the nonreducing ends. Therefore, the presence of multiple chitinases in T. chitonophagus with different modes of cleavage may contribute to its unique ability to efficiently degrade chitin.ImportanceA structurally novel chitinase, Tc-ChiD, was identified from Thermococcus chitonophagus, a hyperthermophilic archaeon. The protein contains a signal peptide for secretion, two chitin-binding domains, and a catalytic domain that shows no similarity with previously characterized chitinases. Tc-ChiD thus represents a new family of chitinases. Tc-ChiD is an exo-type chitinase that recognizes the reducing end of chitin chains and releases (GlcNAc)2 or (GlcNAc)3 As a thermostable chitinase that recognizes the reducing end of chitin chains was not previously known, Tc-ChiD may be useful in a wide range of enzyme-based technologies to degrade and utilize chitin.
| S-EPMC4959179 | biostudies-literature
Project description:A novel, facultatively aerobic, heterotrophic hyperthermophilic archaeon was isolated from a terrestrial hot spring in the Philippines. Cells of the new isolate, strain VA1, were rod-shaped with a length of 1.5 to 10 microm and a width of 0.5 to 1.0 microm. Isolate VA1 grew optimally at 90 to 95 degrees C and pH 7.0 in atmospheric air. Oxygen served as a final electron acceptor under aerobic growth conditions, and vigorous shaking of the medium significantly enhanced growth. Elemental sulfur inhibited cell growth under aerobic growth conditions, whereas thiosulfate stimulated cell growth. Under anaerobic growth conditions, nitrate served as a final electron acceptor, but nitrite or sulfur-containing compounds such as elemental sulfur, thiosulfate, sulfate and sulfite could not act as final electron acceptors. The G+C content of the genomic DNA was 51 mol%. Phylogenetic analysis based on 16S rRNA sequences indicated that strain VA1 exhibited close relationships to species of the genus Pyrobaculum. A DNA-DNA hybridization study revealed a low level of similarity (< or = 18%) between strain VA1 and previously described members of the genus Pyrobaculum. Physiological characteristics also indicated that strain VA1 was distinct from these Pyrobaculum species. Our results indicate that isolate VA1 represents a novel species, named Pyrobaculum calidifontis.
| S-EPMC2685560 | biostudies-literature
Project description:Lipoic acid is a sulfur-containing cofactor and a component of the glycine cleavage system (GCS) involved in C1 compound metabolism and the 2-oxoacid dehydrogenases that catalyze the oxidative decarboxylation of 2-oxoacids. Lipoic acid is found in all domains of life and is generally synthesized as a lipoyl group on the H-protein of the GCS or the E2 subunit of 2-oxoacid dehydrogenases. Lipoyl synthase catalyzes the insertion of two sulfur atoms to the C-6 and C-8 carbon atoms of the octanoyl moiety on the octanoyl-H-protein or octanoyl-E2 subunit. Although the hyperthermophilic archaeon Thermococcus kodakarensis seemed able to synthesize lipoic acid, a classical lipoyl synthase (LipA) gene homolog cannot be found on the genome. In this study, we aimed to identify the lipoyl synthase in this organism. Genome information analysis suggested that the TK2109 and TK2248 genes, which had been annotated as biotin synthase (BioB), are both involved in lipoic acid metabolism. Based on the chemical reaction catalyzed by BioB, we predicted that the genes encode proteins that catalyze the lipoyl synthase reaction. Genetic analysis of TK2109 and TK2248 provided evidence that these genes are involved in lipoic acid biosynthesis. The purified TK2109 and TK2248 recombinant proteins exhibited lipoyl synthase activity toward a chemically synthesized octanoyl-octapeptide. These in vivo and in vitro analyses indicated that the TK2109 and TK2248 genes encode a structurally novel lipoyl synthase. TK2109 and TK2248 homologs are widely distributed among the archaeal genomes, suggesting that in addition to the LipA homologs, the two proteins represent a new group of lipoyl synthases in archaea.IMPORTANCE Lipoic acid is an essential cofactor for GCS and 2-oxoacid dehydrogenases, and α-lipoic acid has been utilized as a medicine and attracted attention as a supplement due to its antioxidant activity. The biosynthesis pathways of lipoic acid have been established in Bacteria and Eucarya but not in Archaea Although some archaeal species, including Sulfolobus, possess a classical lipoyl synthase (LipA) gene homolog, many archaeal species, including T. kodakarensis, do not. In addition, the biosynthesis mechanism of the octanoyl moiety, a precursor for lipoyl group biosynthesis, is also unknown for many archaea. As the enzyme identified in T. kodakarensis most likely represents a new group of lipoyl synthases in Archaea, the results obtained in this study provide an important step in understanding how lipoic acid is synthesized in this domain and how the two structurally distinct lipoyl synthases evolved in nature.
| S-EPMC7657641 | biostudies-literature
Project description:BACKGROUND:Thermococcus litoralis is a heterotrophic facultative sulfur dependent hyperthermophilic Archaeon, which was isolated from a shallow submarine thermal spring. It has been successfully used in a two-stage fermentation system, where various keratinaceous wastes of animal origin were converted to biohydrogen. In this system T. litoralis performed better than its close relative, P. furiosus. Therefore, new alternative enzymes involved in peptide and hydrogen metabolism were assumed in T. litoralis. RESULTS:An about 10.5 kb long genomic region was isolated and sequenced from Thermococcus litoralis. In silico analysis revealed that the region contained a putative operon consisting of eight genes: the fdhAB genes coding for a formate dehydrogenase and the mhyCDEFGH genes encoding a [NiFe] hydrogenase belonging to the group of the H2-evolving, energy-conserving, membrane-bound hydrogenases. Reverse transcription linked quantitative Real-Time PCR and Western blotting experiments showed that the expression of the fdh-mhy operon was up-regulated during fermentative growth on peptides and down-regulated in cells cultivated in the presence of sulfur. Immunoblotting and protein separation experiments performed on cell fractions indicated that the formate dehydrogenase part of the complex is associated to the membrane-bound [NiFe] hydrogenase. CONCLUSION:The formate dehydrogenase together with the membrane-bound [NiFe] hydrogenase formed a formate hydrogenlyase (formate dehydrogenase coupled hydrogenase, FDH-MHY) complex. The expression data suggested that its physiological role is linked to the removal of formate likely generated during anaerobic peptide fermentation.
| S-EPMC2432063 | biostudies-literature
Project description:Genomic analysis of a hyperthermophilic archaeon, Thermococcus sp. strain NA1, revealed the presence of a 1,068-bp open reading frame encoding a protein consisting of 356 amino acids with a calculated molecular mass of 39,714 Da (GenBank accession no. DQ144132). Sequence analysis showed that it was similar to the putative aminopeptidase P (APP) of Thermococcus kodakaraensis KOD1. Amino acid residues important for catalytic activity and the metal binding ligands conserved in bacterial, nematode, insect, and mammalian APPs were also conserved in the Thermococcus sp. strain NA1 APP. The archaeal APP, designated TNA1_APP (Thermococcus sp. strain NA1 APP), was cloned and expressed in Escherichia coli. The recombinant enzyme hydrolyzed the amino-terminal Xaa-Pro bond of Lys(Nepsilon-Abz)-Pro-Pro-pNA and the dipeptide Met-Pro (Km, 0.96 mM), revealing its functional identity. Further enzyme characterization showed the enzyme to be a Co2+-, Mn2+-, or Zn2+-dependent metallopeptidase. Optimal APP activity with Met-Pro as the substrate occurred at pH 5 and a temperature of 100 degrees C. The APP was thermostable, with a half-life of >100 min at 80 degrees C. This study represents the first characterization of a hyperthermophilic archaeon APP.
| S-EPMC1393192 | biostudies-literature
Project description:Prokaryotes have relatively small genomes, densely-packed with protein-encoding sequences. RNA sequencing has, however, revealed surprisingly complex transcriptomes and here we report the transcripts present in the model hyperthermophilic Archaeon, Thermococcus kodakarensis, under different physiological conditions.Sequencing cDNA libraries, generated from RNA isolated from cells under different growth and metabolic conditions has identified >2,700 sites of transcription initiation, established a genome-wide map of transcripts, and consensus sequences for transcription initiation and post-transcription regulatory elements. The primary transcription start sites (TSS) upstream of 1,254 annotated genes, plus 644 primary TSS and their promoters within genes, are identified. Most mRNAs have a 5'-untranslated region (5'-UTR) 10 to 50 nt long (median = 16 nt), but ~20% have 5'-UTRs from 50 to 300 nt long and ~14% are leaderless. Approximately 50% of mRNAs contain a consensus ribosome binding sequence. The results identify TSS for 1,018 antisense transcripts, most with sequences complementary to either the 5'- or 3'-region of a sense mRNA, and confirm the presence of transcripts from all three CRISPR loci, the RNase P and 7S RNAs, all tRNAs and rRNAs and 69 predicted snoRNAs. Two putative riboswitch RNAs were present in growing but not in stationary phase cells. The procedure used is designed to identify TSS but, assuming that the number of cDNA reads correlates with transcript abundance, the results also provide a semi-quantitative documentation of the differences in T. kodakarensis genome expression under different growth conditions and confirm previous observations of substrate-dependent specific gene expression. Many previously unanticipated small RNAs have been identified, some with relative low GC contents (? 50%) and sequences that do not fold readily into base-paired secondary structures, contrary to the classical expectations for non-coding RNAs in a hyperthermophile.The results identify >2,700 TSS, including almost all of the primary sites of transcription initiation upstream of annotated genes, plus many secondary sites, sites within genes and sites resulting in antisense transcripts. The T.?kodakarensis genome is small (~2.1 Mbp) and tightly packed with protein-encoding genes, but the transcriptomes established also contain many non-coding RNAs and predict extensive RNA-based regulation in this model Archaeon.
| S-EPMC4247193 | biostudies-literature
Project description:In this study, we developed a gene disruption system for Thermococcus barophilus using simvastatin for positive selection and 5-fluoroorotic acid (5-FOA) for negative selection or counterselection to obtain markerless deletion mutants using single- and double-crossover events. Disruption plasmids carrying flanking regions of each targeted gene were constructed and introduced by transformation into wild-type T. barophilus MP cells. Initially, a pyrF deletion mutant was obtained as a starting point for the construction of further markerless mutants. A deletion of the hisB gene was also constructed in the UBOCC-3256 (?pyrF) background, generating a strain (UBOCC-3260) that was auxotrophic for histidine. A functional pyrF or hisB allele from T. barophilus was inserted into the chromosome of UBOCC-3256 (?pyrF) or UBOCC-3260 (?pyrF ?hisB), allowing homologous complementation of these mutants. The piezophilic genetic tools developed in this study provide a way to construct strains with multiple genetic backgrounds that will allow further genetic studies for hyperthermophilic piezophilic archaea.
| S-EPMC3993132 | biostudies-literature
Project description:Extracellular vesicles (EVs) produced by a sulfur-reducing, hyperthermophilic archaeon, "Thermococcus onnurineus" NA1(T), were purified and characterized. A maximum of four EV bands, showing buoyant densities between 1.1899 and 1.2828 g cm(-3), were observed after CsCl ultracentrifugation. The two major EV bands, B (buoyant density at 25°C [ρ(25)] = 1.2434 g cm(-3)) and C (ρ(25) = 1.2648 g cm(-3)), were separately purified and counted using a qNano particle analyzer. These EVs, showing different buoyant densities, were identically spherical in shape, and their sizes varied from 80 to 210 nm in diameter, with 120- and 190-nm sizes predominant. The average size of DNA packaged into EVs was about 14 kb. The DNA of the EVs in band C was sequenced and assembled. Mapping of the T. onnurineus NA1(T) EV (ToEV) DNA sequences onto the reference genome of the parent archaeon revealed that most genes of T. onnurineus NA1(T) were packaged into EVs, except for an ∼9.4-kb region from TON_0536 to TON_0544. The absence of this specific region of the genome in the EVs was confirmed from band B of the same culture and from bands B and C purified from a different batch culture. The presence of the 3'-terminal sequence and the absence of the 5'-terminal sequence of TON_0536 were repeatedly confirmed. On the basis of these results, we hypothesize that the unpackaged part of the T. onnurineus NA1(T) genome might be related to the process that delivers DNA into ToEVs and/or the mechanism generating the ToEVs themselves.
| S-EPMC4551206 | biostudies-literature
Project description:The archaeon Thermococcus barophilus, one of the most extreme members of hyperthermophilic piezophiles known thus far, is able to grow at temperatures up to 103°C and pressures up to 80 MPa. We analyzed the membrane lipids of T. barophilus by high performance liquid chromatography-mass spectrometry as a function of pressure and temperature. In contrast to previous reports, we show that under optimal growth conditions (40 MPa, 85°C) the membrane spanning tetraether lipid GDGT-0 (sometimes called caldarchaeol) is a major membrane lipid of T. barophilus together with archaeol. Increasing pressure and decreasing temperature lead to an increase of the proportion of archaeol. Reversely, a higher proportion of GDGT-0 is observed under low pressure and high temperature conditions. Noticeably, pressure and temperature fluctuations also impact the level of unsaturation of apolar lipids having an irregular polyisoprenoid carbon skeleton (unsaturated lycopane derivatives), suggesting a structural role for these neutral lipids in the membrane of T. barophilus. Whether these apolar lipids insert in the membrane or not remains to be addressed. However, our results raise questions about the structure of the membrane in this archaeon and other Archaea harboring a mixture of di- and tetraether lipids.
| S-EPMC4612709 | biostudies-literature
Project description:We report the genome sequence of Thermococcus sp. EXT12c isolated from a deep-sea hydrothermal vent at the East Pacific Rise 9°N. Microbes in the genus Thermococcus are able to grow anaerobically at high temperature, around neutral pH, and some of them under high hydrostatic pressure.
| S-EPMC5730676 | biostudies-literature