| a new phylum of archaea represented by a nanosized hyperthermophilic symbiont. | according to small subunit ribosomal rna (ss rrna) sequence comparisons all known archaea belong to the phyla crenarchaeota, euryarchaeota, and--indicated only by environmental dna sequences--to the 'korarchaeota'. here we report the cultivation of a new nanosized hyperthermophilic archaeon from a submarine hot vent. this archaeon cannot be attached to one of these groups and therefore must represent an unknown phylum which we name 'nanoarchaeota' and species, which we name 'nanoarchaeum equitan ... | 2002 | 11986665 |
| detection of 16s rdna sequences representing the novel phylum "nanoarchaeota": indication for a wide distribution in high temperature biotopes. | we screened samples from high temperature biotopes for 16s rrna genes of the novel archaeal phylum "nanoarchaeota". positive pcr amplifications were obtained from yellowstone national park, uzon caldera, and an abyssal vent system. these sequences form a cluster with the sequence of "nanoarchaeum equitans", indicating a wide distribution of this phylum. | 2002 | 12583716 |
| the phylum nanoarchaeota: present knowledge and future perspectives of a unique form of life. | the "nanoarchaeota" are a novel archaeal phylum, forming a unique, deep branch in the 16s rrna based phylogenetic tree of life. "nanoarchaeum equitans", the first cultivated representative, is a hyperthermophilic, anaerobic nano-sized coccus with a genome size of about 490 kb. growth occurs only in coculture with a new chemolithoautotrophic ignicoccus species. | 2003 | 12706504 |
| the genome of nanoarchaeum equitans: insights into early archaeal evolution and derived parasitism. | the hyperthermophile nanoarchaeum equitans is an obligate symbiont growing in coculture with the crenarchaeon ignicoccus. ribosomal protein and rrna-based phylogenies place its branching point early in the archaeal lineage, representing the new archaeal kingdom nanoarchaeota. the n. equitans genome (490,885 base pairs) encodes the machinery for information processing and repair, but lacks genes for lipid, cofactor, amino acid, or nucleotide biosyntheses. it is the smallest microbial genome seque ... | 2003 | 14566062 |
| shrinking genomics. | two bacteria are featured this month, and both are at the lower end of the genome size scale. the first, mycoplasma gallisepticum, belongs to a group of bacteria that have been studied both as important human and animal pathogens and in the pursuit of understanding the essential functions of a self-replicating minimal cell. the second, nanoarchaeum equitans, is an obligate symbiont that only grows in co-culture with another archaeon. n. equitans seems to be the coelacanth of the microbial world- ... | 2004 | 15035003 |
| gene transfers from nanoarchaeota to an ancestor of diplomonads and parabasalids. | rare evolutionary events, such as lateral gene transfers and gene fusions, may be useful to pinpoint, and correlate the timing of, key branches across the tree of life. for example, the shared possession of a transferred gene indicates a phylogenetic relationship among organismal lineages by virtue of their shared common ancestral recipient. here, we present phylogenetic analyses of prolyl-trna and alanyl-trna synthetase genes that indicate lateral gene transfer events to an ancestor of the dipl ... | 2005 | 15356278 |
| composition of the lipids of nanoarchaeum equitans and their origin from its host ignicoccus sp. strain kin4/i. | the contents and nature of the membrane lipids of nanoarchaeum equitans and ignicoccus sp. strain kin4/i, grown at 90 degrees c, and ignicoccus sp. strain kin4/i, cultivated at its lowest and highest growth temperatures (75 degrees c and 95 degrees c) were analyzed. both organisms contained very simple and qualitatively identical assemblages of glycerol ether lipids, showing only differences in the amounts of certain components. lc-ms analyses of the total lipid extracts revealed that archaeol a ... | 2004 | 15492905 |
| nanoarchaeum equitans creates functional trnas from separate genes for their 5'- and 3'-halves. | analysis of the genome sequence of the small hyperthermophilic archaeal parasite nanoarchaeum equitans has not revealed genes encoding the glutamate, histidine, tryptophan and initiator methionine transfer rna species. here we develop a computational approach to genome analysis that searches for widely separated genes encoding trna halves that, on the basis of structural prediction, could form intact trna molecules. a search of the n. equitans genome reveals nine genes that encode trna halves; t ... | 2005 | 15690044 |
| nanoarchaea: representatives of a novel archaeal phylum or a fast-evolving euryarchaeal lineage related to thermococcales? | cultivable archaeal species are assigned to two phyla -- the crenarchaeota and the euryarchaeota -- by a number of important genetic differences, and this ancient split is strongly supported by phylogenetic analysis. the recently described hyperthermophile nanoarchaeum equitans, harboring the smallest cellular genome ever sequenced (480 kb), has been suggested as the representative of a new phylum -- the nanoarchaeota -- that would have diverged before the crenarchaeota/euryarchaeota split. conf ... | 2005 | 15892870 |
| the complete set of trna species in nanoarchaeum equitans. | the archaeal parasite nanoarchaeum equitans was found to generate five trna species via a unique process requiring the assembly of seperate 5' and 3' trna halves [randau, l., munch, r., hohn, m.j., jahn, d. and soll, d. (2005) nanoarchaeum equitans creates functional trnas from separate genes for their 5'- and 3'-halves. nature 433, 537-541]. biochemical evidence was missing for one of the computationally-predicted, joined trnas designated as trna(trp). our rt-pcr and sequencing results identify ... | 2005 | 15893316 |
| [an important mission for microbiologists in the new century-cultivation of the unculturable microorganisms]. | the present review summarizes the recent advances in cultivating the so-called recalcitrant microorganisms in various natural environments. firstly, the use of new electron donors and acceptors reveals a list of unique and previously unrecognized physiotypes (table 1), and the growth supporting reactions include oxidation of phosphite, arsenite, soil humic substances, benzene, fe (ii) and aryl-halides. the novel pure cultures obtained include: desulfatogenum phosphitoxidans, lithochemotrophic ar ... | 2004 | 15973982 |
| evolutionary and functional genomics of the archaea. | in the past two years, archaeal genomics has achieved several breakthroughs. on the evolutionary front the most exciting development was the sequencing and analysis of the genome of nanoarchaeum equitans, a tiny parasitic organism that has only approximately 540 genes. the genome of nanoarchaeum shows signs of extreme rearrangement including the virtual absence of conserved operons and the presence of several split genes. nanoarchaeum is distantly related to other archaea, and it has been propos ... | 2005 | 16111915 |
| the non-monophyletic origin of the trna molecule and the origin of genes only after the evolutionary stage of the last universal common ancestor (luca). | a model has been proposed suggesting that the trna molecule must have originated by direct duplication of an rna hairpin structure [di giulio, m., 1992. on the origin of the transfer rna molecule. j. theor. biol. 159, 199-214]. a non-monophyletic origin of this molecule has also been theorized [di giulio, m., 1999. the non-monophyletic origin of trna molecule. j. theor. biol. 197, 403-414]. in other words, the trna genes evolved only after the evolutionary stage of the last universal common ance ... | 2006 | 16289209 |
| the heteromeric nanoarchaeum equitans splicing endonuclease cleaves noncanonical bulge-helix-bulge motifs of joined trna halves. | among the trna population of the archaeal parasite nanoarchaeum equitans are five species assembled from separate 5' and 3' trna halves and four species derived from trna precursors containing introns. in both groups an intervening sequence element must be removed during trna maturation. a bulge-helix-bulge (bhb) motif is the hallmark structure required by the archaeal splicing endonuclease for recognition and excision of all introns. bhb motifs are recognizable at the joining sites of all five ... | 2005 | 16330750 |
| colonization of nascent, deep-sea hydrothermal vents by a novel archaeal and nanoarchaeal assemblage. | active deep-sea hydrothermal vents are areas of intense mixing and severe thermal and chemical gradients, fostering a biotope rich in novel hyperthermophilic microorganisms and metabolic pathways. the goal of this study was to identify the earliest archaeal colonizers of nascent hydrothermal chimneys, organisms that may be previously uncharacterized as they are quickly replaced by a more stable climax community. during expeditions in 2001 and 2002 to the hydrothermal vents of the east pacific ri ... | 2006 | 16343327 |
| protein trans-splicing and characterization of a split family b-type dna polymerase from the hyperthermophilic archaeal parasite nanoarchaeum equitans. | nanoarchaeum equitans family b-type dna polymerase (neq dna polymerase) is encoded by two separate genes, the large gene coding for the n-terminal part (neq l) of neq dna polymerase and the small gene coding for the c-terminal part (neq s), including a split mini-intein sequence. the two neq dna polymerase genes were cloned and expressed in escherichia coli individually, together (for the neq c), and as a genetically protein splicing-processed form (neq p). the protein trans-spliced neq c was ob ... | 2006 | 16412462 |
| nanoarchaeum equitans is a living fossil. | | 2006 | 16542685 |
| analysis of nanoarchaeum equitans genome and proteome composition: indications for hyperthermophilic and parasitic adaptation. | nanoarchaeum equitans, the only known hyperthermophilic archaeon exhibiting parasitic life style, has raised some new questions about the evolution of the archaea and provided a model of choice to study the genome landmarks correlated with thermo-parasitic adaptation. in this context, we have analyzed the genome and proteome composition of n. equitans and compared the same with those of other mesophiles, hyperthermophiles and obligatory host-associated organisms. | 2006 | 16869956 |
| thymidine kinases in archaea. | twenty-six fully sequenced archaeal genomes were searched for genes coding for putative deoxyribonucleoside kinases (dnks). we identified only 5 human-like thymidine kinase 1 genes (tk1s) and none for non-tk1 kinases. four tk1s were identified in the euryarchaea and one was found in the crenarchaea, while none was found in nanoarchaeum. the identified tk1s have high identity to gram-positive bacteria tk1s. the tk1s from archaea, gram-positive bacteria and eukaryotes share the same common ancesto ... | 2006 | 17065082 |
| splits: a new program for predicting split and intron-containing trna genes at the genome level. | in the archaea, some trna precursors contain intron(s) not only in the anticodon loop region but also in diverse sites of the gene (intron-containing trna or cis-spliced trna). the parasite nanoarchaeum equitans, a member of the nanoarchaeota kingdom, creates functional trna from separate genes, one encoding the 5'-half and the other the 3'-half (split trna or trans-spliced trna). although recent genome projects have revealed a huge amount of nucleotide sequence data in the archaea, a comprehens ... | 2006 | 17274770 |
| ignicoccus hospitalis sp. nov., the host of 'nanoarchaeum equitans'. | a novel chemolithoautotrophic and hyperthermophilic member of the genus ignicoccus was isolated from a submarine hydrothermal system at the kolbeinsey ridge, to the north of iceland. the new isolate showed high similarity to the two species described to date, ignicoccus islandicus and ignicoccus pacificus, in its physiological properties as well as in its unique cell architecture. however, phylogenetic analysis and investigations on the protein composition of the outer membrane demonstrated that ... | 2007 | 17392210 |
| phylogenomic analysis of proteins that are distinctive of archaea and its main subgroups and the origin of methanogenesis. | the archaea are highly diverse in terms of their physiology, metabolism and ecology. presently, very few molecular characteristics are known that are uniquely shared by either all archaea or the different main groups within archaea. the evolutionary relationships among different groups within the euryarchaeota branch are also not clearly understood. | 2007 | 17394648 |
| insights into the autotrophic co2 fixation pathway of the archaeon ignicoccus hospitalis: comprehensive analysis of the central carbon metabolism. | ignicoccus hospitalis is an autotrophic hyperthermophilic archaeon that serves as a host for another parasitic/symbiotic archaeon, nanoarchaeum equitans. in this study, the biosynthetic pathways of i. hospitalis were investigated by in vitro enzymatic analyses, in vivo (13)c-labeling experiments, and genomic analyses. our results suggest the operation of a so far unknown pathway of autotrophic co(2) fixation that starts from acetyl-coenzyme a (coa). the cyclic regeneration of acetyl-coa, the pri ... | 2007 | 17400748 |
| the tree of life might be rooted in the branch leading to nanoarchaeota. | it is suggested that the tree of life might be rooted in the domain of the archaea, in the branch leading to the phylum of nanoarchaeota. this hypothesis seems to be corroborated by the uniqueness and ancestrality of some traits possessed by nanoarchaeum equitans, such as split genes separately codifying for the 5' and 3' halves of the trna molecule. these half genes are the oldest ancestral form of gene we have ever seen. this, along with the absence of operons from the genome of n. equitans, w ... | 2007 | 17689206 |
| superoxide reduction by nanoarchaeum equitans neelaredoxin, an enzyme lacking the highly conserved glutamate iron ligand. | superoxide reductases (sors) are antioxidant enzymes present in many prokaryotes, either anaerobes or microaerophiles, which detoxify superoxide by reducing it to hydrogen peroxide. the reaction mechanism involves the diffusion-limited encounter of superoxide with the reduced iron site and concomitant formation of an fe(3+)-(hydro)peroxo adduct that, upon protonation, leads to the formation of hydrogen peroxide. by the end of this process, a glutamate residue coordinates the ferric ion, acting a ... | 2008 | 17968598 |
| nanoarchaeum equitans and ignicoccus hospitalis: new insights into a unique, intimate association of two archaea. | nanoarchaeum equitans and ignicoccus hospitalis represent a unique, intimate association of two archaea. both form a stable coculture which is mandatory for n. equitans but not for the host i. hospitalis. here, we investigated interactions and mutual influence between these microorganisms. fermentation studies revealed that during exponential growth only about 25% of i. hospitalis cells are occupied by n. equitans cells (one to three cells). the latter strongly proliferate in the stationary phas ... | 2008 | 18165302 |
| sequence evidence in the archaeal genomes that trnas emerged through the combination of ancestral genes as 5' and 3' trna halves. | the discovery of separate 5' and 3' halves of transfer rna (trna) molecules-so-called split trna-in the archaeal parasite nanoarchaeum equitans made us wonder whether ancestral trna was encoded on 1 or 2 genes. we performed a comprehensive phylogenetic analysis of trnas in 45 archaeal species to explore the relationship between the three types of trnas (nonintronic, intronic and split). we classified 1953 mature trna sequences into 22 clusters. all split trnas have shown phylogenetic relationshi ... | 2008 | 18286179 |
| indicators from archaeal secretomes. | just as in the eukarya and the bacteria, members of the archaea need to export proteins beyond the cell membrane. this would be required to fulfill a variety of essential functions such as nutrient acquisition and biotransformations, maintenance of extracellular structures and more. apart from the eukarya and the bacteria however, members of the archaea share a number of unique characteristics. does this uniqueness extend to the protein secretion system? it was the objective of this study to ans ... | 2010 | 18407482 |
| life without rnase p. | the universality of ribonuclease p (rnase p), the ribonucleoprotein essential for transfer rna (trna) 5' maturation, is challenged in the archaeon nanoarchaeum equitans. neither extensive computational analysis of the genome nor biochemical tests in cell extracts revealed the existence of this enzyme. here we show that the conserved placement of its trna gene promoters allows the synthesis of leaderless trnas, whose presence was verified by the observation of 5' triphosphorylated mature trna spe ... | 2008 | 18451863 |
| signature genes as a phylogenomic tool. | gene content has been shown to contain a strong phylogenetic signal, yet its usage for phylogenetic questions is hampered by horizontal gene transfer and parallel gene loss and until now required completely sequenced genomes. here, we introduce an approach that allows the phylogenetic signal in gene content to be applied to any set of sequences, using signature genes for phylogenetic classification. the hundreds of publicly available genomes allow us to identify signature genes at various taxono ... | 2008 | 18492663 |
| the basal phylogenetic position of nanoarchaeum equitans (nanoarchaeota). | using sequences of ribosomal rna from organisms belonging exclusively to the archaea domain and by means of two methods to remove the phylogenetic noise, we investigate the phylogenetic position of nanoarchaeum equitans. the results obtained are compatible with the hypothesis that n. equitans represents a new phylum within the archaea domain because the characteristic long branch of n. equitans in phylogenetic trees is conserved even after most of the phylogenetic noise has been removed, thus im ... | 2008 | 18508702 |
| a dicarboxylate/4-hydroxybutyrate autotrophic carbon assimilation cycle in the hyperthermophilic archaeum ignicoccus hospitalis. | ignicoccus hospitalis is an anaerobic, autotrophic, hyperthermophilic archaeum that serves as a host for the symbiotic/parasitic archaeum nanoarchaeum equitans. it uses a yet unsolved autotrophic co(2) fixation pathway that starts from acetyl-coa (coa), which is reductively carboxylated to pyruvate. pyruvate is converted to phosphoenol-pyruvate (pep), from which glucogenesis as well as oxaloacetate formation branch off. here, we present the complete metabolic cycle by which the primary co(2) acc ... | 2008 | 18511565 |
| nanoarchaeal 16s rrna gene sequences are widely dispersed in hyperthermophilic and mesophilic halophilic environments. | the nanoarchaeota, proposed as the fourth sub-division of the archaea in 2002, are known from a single isolate, nanoarchaeum equitans, which exists in a symbiotic association with the hyperthermophilic crenarchaeote, ignicoccus. n. equitans fails to amplify with standard archaeal 16s pcr primers and can only be amplified using specifically designed primers. we have designed a new set of universal archaeal primers that amplify the 16s rrna gene of all four archaeal sub-divisions, and present two ... | 2008 | 18553053 |
| insight into the proteome of the hyperthermophilic crenarchaeon ignicoccus hospitalis: the major cytosolic and membrane proteins. | ignicoccus hospitalis, a hyperthermophilic, chemolithoautotrophic crenarchaeon, is the host of nanoarchaeum equitans. together, they form an intimate association, the first among archaea. membranes are of fundamental importance for the interaction of i. hospitalis and n. equitans, as they harbour the proteins necessary for the transport of macromolecules like lipids, amino acids, and cofactors between these organisms. here, we investigated the protein inventory of i. hospitalis cells, and were a ... | 2008 | 18584152 |
| the split genes of nanoarchaeum equitans are an ancestral character. | the introns early hypothesis predicts that introns were fundamental in assembling the first genes. in nanoarchaeum equitans some genes are split into two. if these split genes were the ancestral forms, as suggested by the introns early hypothesis, then the end-beginning of the two parts of the split protein in a multiple alignment with the orthologous proteins from the eukarya and arachaea domains should make a clear prediction on where the intron in the homologous eukaryotic gene should be posi ... | 2008 | 18590807 |
| ignicoccus hospitalis and nanoarchaeum equitans: ultrastructure, cell-cell interaction, and 3d reconstruction from serial sections of freeze-substituted cells and by electron cryotomography. | ultrastructure and intercellular interaction of ignicoccus hospitalis and nanoarchaeum equitans were investigated using two different electron microscopy approaches, by three-dimensional reconstructions from serial sections, and by electron cryotomography. serial sections were assembled into 3d reconstructions, for visualizing the unusual complexity of i. hospitalis, its huge periplasmic space, the vesiculating cytoplasmic membrane, and the outer membrane. the cytoplasm contains fibres which are ... | 2008 | 18622597 |
| unique substrate spectrum and pcr application of nanoarchaeum equitans family b dna polymerase. | the known archaeal family b dna polymerases are unable to participate in the pcr in the presence of uracil. here, we report on a novel archaeal family b dna polymerase from nanoarchaeum equitans that can successfully utilize deaminated bases such as uracil and hypoxanthine and on its application to pcr. n. equitans family b dna polymerase (neq dna polymerase) produced lambda dna fragments up to 10 kb with an approximately 2.2-fold-lower error rate (5.53 x 10(-6)) than taq dna polymerase (11.98 x ... | 2008 | 18791030 |
| a genomic analysis of the archaeal system ignicoccus hospitalis-nanoarchaeum equitans. | the relationship between the hyperthermophiles ignicoccus hospitalis and nanoarchaeum equitans is the only known example of a specific association between two species of archaea. little is known about the mechanisms that enable this relationship. | 2008 | 19000309 |
| nanoarchaeal origin of histone h3? | neq288, one of two archaeal histones in nanoarchaeum equitans, has a unique four-residue insertion that closely resembles an insertion in the eukaryotic histone h3 lineage. neq288 bound dna but did not compact dna in vitro in the absence of neq348, the second n. equitans archaeal histone. the properties of neq288 suggest an intermediate between the archaeal and h3 histone lineages and an evolutionary step toward the now-mandatory assembly of eukaryotic histones into heterodimers. | 2009 | 19047349 |
| characterization of a key trifunctional enzyme for aromatic amino acid biosynthesis in archaeoglobus fulgidus. | in the aromatic amino acid biosynthesis pathway, chorismate presents a branch point intermediate that is converted to tryptophan, phenylalanine (phe), and tyrosine (tyr). in bacteria, three enzymes catalyze the conversion of chorismate to hydroxyphenylpyruvate or pyruvate. the enzymes, chorismate mutase (cm), prephenate dehydratase (pdt), and prephenate dehydrogenase (pdhg) are either present as distinct proteins or fusions combining two activities. gene locus af0227 of archaeoglobus fulgidus is ... | 2009 | 19082689 |
| the interaction of nanoarchaeum equitans with ignicoccus hospitalis: proteins in the contact site between two cells. | the two archaea ignicoccus hospitalis and nanoarchaeum equitans form a unique intimate association, the character of which is not yet fully understood. electron microscopic investigations show that at least two modes of cell-cell interactions exist: (i) the two cells are interconnected via thin fibres; and (ii) the two cell surfaces are in direct contact with each other. in order to shed further light on the molecules involved, we isolated a protein complex, by using detergent-induced solubiliza ... | 2009 | 19143616 |
| happy together: genomic insights into the unique nanoarchaeum/ignicoccus association. | the complete genome sequence of the crenarchaeon ignicoccus hospitalis published recently in genome biology provides a great leap forward in the dissection of its unique association with another hyperthermophilic archaeon, nanoarchaeum equitans. | 2009 | 19216728 |
| resonance raman study of the superoxide reductase from archaeoglobus fulgidus, e12 mutants and a 'natural variant'. | the resonance raman (rr) spectra of the oxidized wild-type archaeoglobus fuglidus 1fe-superoxide reductase (sor), e12v and e12q mutants were studied at different ph conditions upon excitation in resonance with the ph-dependent charge transfer transition to the ferric iron. the wild-type sor from nanoarchaeum equitans that lacks the highly conserved glutamate residue was investigated as a 'natural variant'. no substantial differences were observed in the rr spectra of the active sites of the a. f ... | 2009 | 19290353 |
| a comparison among the models proposed to explain the origin of the trna molecule: a synthesis. | a comparison is made among all the models proposed to explain the origin of the trna molecule. the conclusion reached is that, for the model predicting that the trna molecule originated after the assembly of two hairpin-like structures, molecular fossils have been found in the half-genes of the trnas of nanoarchaeum equitans. these might be the witnesses of the transition stage predicted by the model through which the evolution of the trna molecule passed, thus providing considerable corroborati ... | 2009 | 19488799 |
| crystal structure and assembly of the functional nanoarchaeum equitans trna splicing endonuclease. | the rna splicing and processing endonuclease from nanoarchaeum equitans (neq) belongs to the recently identified (alphabeta)(2) family of splicing endonucleases that require two different subunits for splicing activity. n. equitans splicing endonuclease comprises the catalytic subunit (neq205) and the structural subunit (neq261). here, we report the crystal structure of the functional neq enzyme at 2.1 a containing both subunits, as well as that of the neq261 subunit alone at 2.2 a. the function ... | 2009 | 19578064 |
| formal proof that the split genes of trnas of nanoarchaeum equitans are an ancestral character. | a proof is given that the genes of the trna molecule of nanoarchaeum equitans split into the 5' and 3' halves are an ancestral trait. first, the existence of a natural succession of evolutionary stages will be proven, formed in the order of the three gene structures of trnas known today: (i) the split genes of trnas, (ii) the genes of trnas with introns, and (iii) the genes of trnas continuously codifying for the trna molecule. this succession of evolutionary stages identifies the split genes of ... | 2009 | 19760446 |
| separate and combined biochemical activities of the subunits of a naturally split reverse gyrase. | reverse gyrase reanneals denatured dna and induces positive supercoils in dna, an activity that is critical for life at very high temperatures. positive supercoiling occurs by a poorly understood mechanism involving the coordination of a topoisomerase domain and a helicase-like domain. in the parasitic archaeon nanoarchaeum equitans, these domains occur as separate subunits. we express the subunits, and characterize them both in isolation and as a heterodimer. each subunit tightly associates and ... | 2010 | 20929866 |
| the last universal common ancestor (luca) and the ancestors of archaea and bacteria were progenotes. | the trna split genes of nanoarchaeum equitans and the met-trna(fmet) → fmet-trna(fmet) pathway, identifiable as ancestral traits, and the late appearance of dna are used to understand the evolutionary stage at which the progenote → genote transition took place. the arguments are such as to impose that not only was the last universal common ancestor (luca) a progenote, but the ancestors of archaea and bacteria were too. therefore, the progenote → genote transition took place in a very advanced st ... | 2010 | 21079939 |
| discovery of a minimal form of rnase p in pyrobaculum. | rnase p rna is an ancient, nearly universal feature of life. as part of the ribonucleoprotein rnase p complex, the rna component catalyzes essential removal of 5' leaders in pre-trnas. in 2004, li and altman computationally identified the rnase p rna gene in all but three sequenced microbes: nanoarchaeum equitans, pyrobaculum aerophilum, and aquifex aeolicus (all hyperthermophiles) [li y, altman s (2004) rna 10:1533-1540]. a recent study concluded that n. equitans does not have or require rnase ... | 2010 | 21135215 |
| superoxide reductase from nanoarchaeum equitans: expression, purification, crystallization and preliminary x-ray crystallographic analysis. | superoxide reductases (sors) are the most recent oxygen-detoxification system to be identified in anaerobic and microaerobic bacteria and archaea. sors are metalloproteins that are characterized by their possession of a catalytic nonhaem iron centre in the ferrous form coordinated by four histidine ligands and one cysteine ligand. ignicoccus hospitalis, a hyperthermophilic crenarchaeon, is the only organism known to date to serve as a host for nanoarchaeum equitans, a nanosized hyperthermophilic ... | 2011 | 21543869 |
| archaeal symbionts and parasites. | several species of archaea are involved in symbiotic or parasitic associations with representatives of eukarya, bacteria and other archaea. eukaryal interactions include different members of methanogens, found in the gut of arthropods, in the rumen of cattle, and in the human intestine, while cenarchaeum symbiosum is a partner of a marine sponge. examples for bacterial-archaeal associations are the anaerobic methane oxidation consortia and the sm1 euryarchaeon with its highly unusual 'hami' as e ... | 2011 | 21571580 |
| nanoarchaeum equitans failed to maintain the balance between dna stability and melting potential. | | 2011 | 21606613 |
| close interspecies interactions between prokaryotes from sulfureous environments. | green sulfur bacteria are obligate photolithoautotrophs that require highly reducing conditions for growth and can utilize only a very limited number of carbon substrates. these bacteria thus inhabit a very narrow ecologic niche. however, several green sulfur bacteria have overcome the limits of immobility by entering into a symbiosis with motile betaproteobacteria in a type of multicellular association termed phototrophic consortia. one of these consortia, "chlorochromatium aggregatum," has rec ... | 2011 | 21779277 |
| proteomic characterization of cellular and molecular processes that enable the nanoarchaeum equitans-ignicoccus hospitalis relationship. | nanoarchaeum equitans, the only cultured representative of the nanoarchaeota, is dependent on direct physical contact with its host, the hyperthermophile ignicoccus hospitalis. the molecular mechanisms that enable this relationship are unknown. using whole-cell proteomics, differences in the relative abundance of >75% of predicted protein-coding genes from both archaea were measured to identify the specific response of i. hospitalis to the presence of n. equitans on its surface. a purified n. eq ... | 2011 | 21826220 |