Archaeoglobales
Bacterial origin for the isoprenoid biosynthesis enzyme HMG-CoA reductase of the archaeal orders Thermoplasmatales and Archaeoglobales. (1/9)
The enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase or HMGR) fulfills an essential role in archaea, as it is required for the synthesis of isoprenoid ethers, the main component of archaeal cell membranes. There are two clearly homologous but structurally different classes of the enzyme, one found mainly in eukaryotes and archaea (class 1), and the other found in bacteria (class 2). This feature facilitated the identification of several cases of interdomain lateral gene transfer (LGT), in particular, the bacterial origin for the HMGR gene from the archaeon Archaeoglobus fulgidus. In order to investigate if this LGT event was recent and limited in its scope or had a broad and long-term impact on the recipient and its related lineages, the HMGR gene was amplified and sequenced from a variety of archaea. The survey covered close relatives of A. fulgidus, the only archaeon known prior to this study to possess a bacterial-like HMGR; representatives of each main euryarchaeal group were also inspected. All culturable members of the archaeal group Archaeoglobales were found to display an HMGR very similar to the enzyme of the bacterium Pseudomonas mevalonii. Surprisingly, two species of the genus Thermoplasma also harbor an HMGR of bacterial origin highly similar to the enzymes found in the Archaeoglobales. Phylogenetic analyses of the HMGR gene and comparisons to reference phylogenies from other genes confirm a common bacterial origin for the HMGRs of Thermoplasmatales and Archaeoglobales. The most likely explanation of these results includes an initial bacteria-to-archaea transfer, followed by a another event between archaea. Their presence in two divergent archaeal lineages suggests an important adaptive role for these laterally transferred genes. (+info)Characterisation of Archaeglobus fulgidus AlkA hypoxanthine DNA glycosylase activity. (2/9)
The AlkA protein from the archaebacterium Archaeglobus fulgidus was characterised with respect to release of hypoxanthine from DNA. The hypoxanthine glycosylase activity had optimal activity at 60 degrees C at pH 5.0. The enzyme released hypoxanthine from substrates with a preference for dI:dG >> dI:dT > dI:dC > dI:dA. The presence of a mismatch on either side of the dIMP in the substrate reduced excision efficiency of the hypoxanthine residue at neutral pH, while a mismatch on both sides of the dIMP resulted in total loss of excision. Release of hypoxanthine from DNA required a minimum of two bases on the 5' side and four bases on the 3' side of the dIMP residue. (+info)Structural and thermodynamic evidence for a stabilizing role of Nop5p in S-adenosyl-L-methionine binding to fibrillarin. (3/9)
In Archaea, fibrillarin and Nop5p form the core complex of box C/D small ribonucleoprotein particles, which are responsible for site-specific 2'-hydroxyl methylation of ribosomal and transfer RNAs. Fibrillarin has a conserved methyltransferase fold and employs S-adenosyl-l-methionine (AdoMet) as the cofactor in methyl transfer reactions. Comparison between recently determined crystal structures of free fibrillarin and fibrillarin-Nop5p-AdoMet tertiary complex revealed large conformational differences at the cofactor-binding site in fibrillarin. To identify the structural elements responsible for these large conformational differences, we refined a crystal structure of Archaeoglobus fulgidus fibrillarin-Nop5p binary complex at 3.5 A. This structure exhibited a pre-formed backbone geometry at the cofactor binding site similar to that when the cofactor is bound, suggesting that binding of Nop5p alone to fibrillarin is sufficient to stabilize the AdoMet-binding pocket. Calorimetry studies of cofactor binding to fibrillarin alone and to fibrillarin-Nop5p binary complex provided further support for this role of Nop5p. Mutagenesis and thermodynamic data showed that a cation-pi bridge formed between Tyr-89 of fibrillarin and Arg-169 of Nop5p, although dispensable for in vitro methylation activity, could partially account for the enhanced binding of cofactor to fibrillarin by Nop5p. Finally, assessment of cofactor-binding thermodynamics and catalytic activities of enzyme mutants identified three additional fibrillarin residues (Thr-70, Glu-88, and Asp-133) to be important for cofactor binding and for catalysis. (+info)Heat shock response of Archaeoglobus fulgidus. (4/9)
The heat shock response of the hyperthermophilic archaeon Archaeoglobus fulgidus strain VC-16 was studied using whole-genome microarrays. On the basis of the resulting expression profiles, approximately 350 of the 2,410 open reading frames (ORFs) (ca. 14%) exhibited increased or decreased transcript abundance. These span a range of cell functions, including energy production, amino acid metabolism, and signal transduction, where the majority are uncharacterized. One ORF called AF1298 was identified that contains a putative helix-turn-helix DNA binding motif. The gene product, HSR1, was expressed and purified from Escherichia coli and was used to characterize specific DNA recognition regions upstream of two A. fulgidus genes, AF1298 and AF1971. The results indicate that AF1298 is autoregulated and is part of an operon with two downstream genes that encode a small heat shock protein, Hsp20, and cdc48, an AAA+ ATPase. The DNase I footprints using HSR1 suggest the presence of a cis-binding motif upstream of AF1298 consisting of CTAAC-N5-GTTAG. Since AF1298 is negatively regulated in response to heat shock and encodes a protein only distantly related to the N-terminal DNA binding domain of Phr of Pyrococcus furiosus, these results suggest that HSR1 and Phr may belong to an evolutionarily diverse protein family involved in heat shock regulation in hyperthermophilic and mesophilic Archaea organisms. (+info)Conserved residues in the HAMP domain define a new family of proposed bipartite energy taxis receptors. (5/9)
(+info)Anaerobic oxidation of benzene by the hyperthermophilic archaeon Ferroglobus placidus. (6/9)
(+info)Crystallization and preliminary X-ray diffraction analysis of an archaeal tRNA-modification enzyme, TiaS, complexed with tRNA(Ile2) and ATP. (7/9)
(+info)Pyrosequencing reveals high-temperature cellulolytic microbial consortia in Great Boiling Spring after in situ lignocellulose enrichment. (8/9)
(+info)Archaeoglobales is an order of archaea, a group of single-celled microorganisms that are distinct from bacteria and eukaryotes. Archaea are extremophiles, meaning they can survive in harsh environments that are hostile to most other life forms.
Archaeoglobales are unique because they are thermophilic, which means they thrive in high-temperature environments, typically between 65 and 95°C (149-203°F). They are also sulfate-reducing organisms, which means they obtain energy by reducing sulfate to hydrogen sulfide, using organic compounds as electron donors.
These archaea have been found in various environments, including deep-sea hydrothermal vents, hot springs, and oil reservoirs. They play an essential role in the global carbon and sulfur cycles and have potential applications in bioremediation and bioenergy production.
I'm sorry for any confusion, but "Thermoplasmales" is not a recognized term in medical or scientific nomenclature. It seems that there might be a spelling mistake or a misunderstanding of the correct term. If you meant to ask about Thermoplasmatales, which is an order of archaea (single-celled microorganisms), I would be happy to provide more information on that.
Thermoplasmatales are a group of extremophilic archaea, meaning they thrive in extreme environments that are hostile to most other life forms. They are typically found in environments with high temperatures (50-90°C), low pH levels (around 1-4), and high heavy metal concentrations. These organisms have unique adaptations that allow them to survive under such harsh conditions, including the ability to produce energy through sulfur metabolism and a unique cell wall structure that lacks peptidoglycan.
If you meant to ask about something else or need more information on Thermoplasmatales, please let me know!
Archaeoglobus
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Assessment of the Carbon Monoxide Metabolism of the Hyperthermophilic Sulfate-Reducing Archaeon Archaeoglobus fulgidus VC-16 by...
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Genus: Archaeoglobus
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MESH TREE NUMBER CHANGES - 2010 MeSH. August 28, 2009
Species Report for: Archaeoglobus fulgidus
Archaeoglobaceae1
- Archaeoglobi Archaeoglobales Archaeoglobaceae Archaeoglobus Archaeoglobus fulgidus (strain ATCC 49558 / DSM 4304 / JCM 9628 / NBRC. (expasy.org)
43041
- General Information: This is the type strain (DSM 4304) of the Archaeoglobales, and was isolated from a geothermally heated sea floor at Vulcano Island, Italy. (up.ac.za)