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facile distinction of neutral and acidic tetraether lipids in archaea membrane by halogen atom adduct ions in electrospray ionization mass spectrometry.calditocaldarchaeol (neutral tetraether lipid) from sulfolobus acidocaldarius (acidothermophilic archaea) and intact total lipid from the thermoacidophilic archaea sulfolobus sp. was examined by electrospray ionization time-of-flight mass spectrometry in the negative-ion mode using high resolution. when the sample was injected as a solution in a 3:1 mixture of methanol (meoh) and chloroform (chcl(3)) using an infusion system, the total ether lipid afforded molecular-related ions as [m - h](-) fo ...200211857765
electron cryo-microscopy of vat, the archaeal p97/cdc48 homologue from thermoplasma acidophilum.vat (valosine containing protein-like atpase from thermoplasma acidophilum), an archaeal member of the aaa-family (atpases associated with a variety of cellular activities) that possesses foldase as well as unfoldase-activity, forms homo-hexameric rings like its eukaryotic homologues p97 and cdc48. the vat-monomer exhibits the tripartite domain architecture typical for type ii aaa-atpases: n-d1-d2, whereby n is the substrate binding n-terminal domain preceding domains d1 and d2, both containing ...200211955016
purifying and directional selection in overlapping prokaryotic genes.in overlapping genes, the same dna sequence codes for two proteins using different reading frames. analysis of overlapping genes can help in understanding the mode of evolution of a coding region from noncoding dna. we identified 71 pairs of convergent genes, with overlapping 3' ends longer than 15 nucleotides, that are conserved in at least two prokaryotic genomes. among the overlap regions, we observed a statistically significant bias towards the 123:132 phase (i.e. the second codon base in on ...200212047938
acidophiles of saline water at thermal vents of vulcano, italy.dna was extracted from samples taken from close to acidic hydrothermal vents on shore of the aeolian island of vulcano (italy). rna gene sequences were amplified by pcr, cloned, and sequenced. a sequence with an origin in samples at 35 degrees and 45 degrees c corresponded to that of a novel acidithiobacillus species that was isolated from water close to the vents. novel, iron-oxidizing mesophilic acidophiles were isolated through enrichment cultures with ferrous iron but were not represented in ...200212072955
specific orientation and two-dimensional crystallization of the proteasome at metal-chelating lipid interfaces.the potential of a protein-engineered his tag to immobilize macromolecules in a predictable orientation at metal-chelating lipid interfaces was investigated using recombinant 20 s proteasomes his-tagged in various positions. electron micrographs demonstrated that the orientation of proteasomes bound to chelating lipid films could be controlled via the location of their his tags: proteasomes his-tagged at their sides displayed exclusively side-on views, while proteasomes his-tagged at their ends ...200212114506
identification of the gene (bbs1) most commonly involved in bardet-biedl syndrome, a complex human obesity syndrome.bardet-biedl syndrome (bbs, omim 209900) is a genetic disorder with the primary features of obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation and hypogenitalism. individuals with bbs are also at increased risk for diabetes mellitus, hypertension and congenital heart disease. what was once thought to be a homogeneous autosomal recessive disorder is now known to map to at least six loci: 11q13 (bbs1), 16q21 (bbs2), 3p13 p12 (bbs3), 15q22.3 q23 (bbs4), 2q31 (bbs5 ...200212118255
expression of long- and short-type fk506 binding proteins in hyperthermophilic archaea.it has been reported that the hyperthermophilic archaeon, methanococcus jannaschii, possesses two fkbp (fk506 binding protein) genes in the genome, one being 26 kda fkbp (long-type fkbp) and the other, 18 kda fkbp (short-type fkbp). fkbp is a family of peptidyl-prolyl cis-trans isomerases (ppiases). in order to clarify the difference between their roles in archaeal cells, they were expressed in escherichia coli, and their ppiase and chaperone-like protein-folding activities were investigated. th ...200212119099
formation of metal nanoclusters on specific surface sites of protein molecules.during vacuum condensation of metals on frozen proteins, nanoclusters are preferentially formed at specific surface sites (decoration). understanding the nature of metal/protein interaction is of interest for structure analysis and is also important in the fields of biocompatibility and sensor development. studies on the interaction between metal and distinct areas on the protein which enhance or impede the probability for cluster formation require information on the structural details of the pr ...200212144790
structures of the tricorn-interacting aminopeptidase f1 with different ligands explain its catalytic mechanism.f1 is a 33.5 kda serine peptidase of the alpha/beta-hydrolase family from the archaeon thermoplasma acidophilum. subsequent to proteasomal protein degradation, tricorn generates small peptides, which are cleaved by f1 to yield single amino acids. we have solved the crystal structure of f1 with multiwavelength anomalous dispersion (mad) phasing at 1.8 a resolution. in addition to the conserved catalytic domain, the structure reveals a chiefly alpha-helical domain capping the catalytic triad. thus ...200212374735
structural basis for the processive protein degradation by tricorn protease.cell survival critically depends on the efficient use of available resources. this includes both the clearance and the recycling of those protein components that have become futile or defective. several proteins sequentially accomplish this complex task. the proteasome serves as an initial protein shredder and generates peptides of 7-12 amino acids in length. in general, these products are useless burden to the cell and need further processing. a few years ago, a proteolytic system was identifie ...200212437101
novel thermoactive glucoamylases from the thermoacidophilic archaea thermoplasma acidophilum, picrophilus torridus and picrophilus oshimae.the thermoacidophilic archaea thermoplasma acidophilum (optimal growth at 60 degrees c and ph 1-2), picrophilus torridus and picrophilus oshimae (optimal growth at 60 degrees c and ph 0.7) were able to utilize starch as sole carbon source. during growth these microorganisms secreted heat and acid-stable glucoamylases into the culture fluid. applying sds gel electrophoresis activity bands were detected with appearent molecular mass (mw) of 141.0, 95.0 kda for t. acidophilum, 133.0, 90.0 kda for p ...200212448707
recovery of novel bacterial diversity from a forested wetland impacted by reject coal.sulphide mineral mining together with improperly contained sulphur-rich coal represents a significant environmental problem caused by leaching of toxic material. the savannah river site's d-area harbours a 22-year-old exposed reject coal pile (rcp) from which acidic, metal rich, saline runoff has impacted an adjacent forested wetland. in order to assess the bacterial community composition of this region, composite sediment samples were collected at three points along a contamination gradient (hi ...200212460285
navigation inside a protease: substrate selection and product exit in the tricorn protease from thermoplasma acidophilum.the proposed pathway and mechanism of substrate entry and product egress in the hexameric d3 symmetric tricorn protease from thermoplasma acidophilum were explored by crystallographic studies of ligand complexes and by structure-based mutagenesis. obstruction of the pore within the 7-bladed beta-propeller (beta7) domain by alkylation or oxidation of an engineered double cysteine mutant strongly decreased enzymatic activities. in line herewith, the crystal structure of the tricorn protease in com ...200212470958
mechanosensitive channel of thermoplasma, the cell wall-less archaea: cloning and molecular characterization.by using a functional approach of reconstituting detergent-solubilized membrane proteins into liposomes and following their function in patch-clamp experiments, we identified a novel mechanosensitive (ms) channel in the thermophilic cell wall-less archaeon thermoplasma volcanium. sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page) of the enriched protein fractions revealed a band of approx 15 kda comparable to mscl, the bacterial ms channel of large conductance. 20 n-terminal re ...200111898860
the evolution of lipids.living organisms on the earth which are divided into three major domains--archaea, bacteria, and eucarya, probably came from a common ancestral cell. because there are many thermophilic microorganisms near the root of the universal phylogenetic tree, the common ancestral cell should be considered to be a thermophilic microorganism. the existence of a cell is necessary for the living organisms; the cell membrane is the essential structural component of a cell, so its amphiphilic property is vital ...200111803978
prediction of the archaeal exosome and its connections with the proteasome and the translation and transcription machineries by a comparative-genomic approach.by comparing the gene order in the completely sequenced archaeal genomes complemented by sequence profile analysis, we predict the existence and protein composition of the archaeal counterpart of the eukaryotic exosome, a complex of rnases, rna-binding proteins, and helicases that mediates processing and 3'->5' degradation of a variety of rna species. the majority of the predicted archaeal exosome subunits are encoded in what appears to be a previously undetected superoperon. in methanobacterium ...200111157787
quinone profiles of thermoplasma acidophilum ho-62.quinones of thermoplasma acidophilum ho-62 were analyzed by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance. menaquinone, methionaquinone, and 2-trans and 2-cis forms of thermoplasmaquinone were identified. the relative amount of thermoplasmaquinone increased under anaerobic conditions, and those of menaquinone and methionaquinone increased under aerobic conditions.200111157962
the chaperones of the archaeon thermoplasma acidophilum.chaperonesare an essential component of a cell's ability to respond to environmental challenges. chaperones have been studied primarily in bacteria, but in recent years it has become apparent that some classes of chaperones either are very divergent in bacteria relative to archaea and eukaryotes or are missing entirely. in contrast, a high degree of similarity was found between the chaperonins of archaea and those of the eukaryotic cytosol, which has led to the establishment of archaeal model sy ...200111580262
atp-induced structural change of the thermosome is temperature-dependent.protein folding by chaperonins is powered by atp binding and hydrolysis. atpase activity drives the folding machine through a series of conformational rearrangements, extensively described for the group i chaperonin groel from escherichia coli but still poorly understood for the group ii chaperonins. the latter--archaeal thermosome and eukaryotic tric/cct--function independently of a groes-like cochaperonin and are proposed to rely on protrusions of their own apical domains for opening and closu ...200111580263
review: nucleotide binding to the thermoplasma thermosome: implications for the functional cycle of group ii chaperonins.structural information on group ii chaperonins became available during recent years from electron microscopy and x-ray crystallography. three conformational states have been identified for both archaeal and eukaryotic group ii chaperonins: an open state, a spherical closed conformation, and an intermediate asymmetric bullet-shaped form. however, the functional cycle of group ii chaperonins appears less well understood, although major principles are conserved when compared to group i chaperonins: ...200111580264
gene duplication and the evolution of group ii chaperonins: implications for structure and function.chaperonins are multisubunit protein-folding assemblies. they are composed of two distinct structural classes, which also have a characteristic phylogenetic distribution. group i chaperonins (called groel/cpn60/hsp60) are present in bacteria and eukaryotic organelles while group ii chaperonins are found in archaea (called the thermosome or tf55) and the cytoplasm of eukaryotes (called cct or tric). gene duplication has been an important force in the evolution of group ii chaperonins: archaea pos ...200111580265
the hunt for living gold. the search for organisms in extreme environments yields useful enzymes for industry. 200111713183
crystal structure of the tricorn protease reveals a protein disassembly line.the degradation of cytosolic proteins is carried out predominantly by the proteasome, which generates peptides of 7-9 amino acids long. these products need further processing. recently, a proteolytic system was identified in the model organism thermoplasma acidophilum that performs this processing. the hexameric core protein of this modular system, referred to as tricorn protease, is a 720k protease that is able to assemble further into a giant icosahedral capsid, as determined by electron micro ...200111719810
hydration and molecular motions in synthetic phytanyl-chained glycolipid vesicle membranes.proton permeation rates across membranes of a synthetic branch-chained glycolipid, 1,3-di-o-phytanyl-2-o-(beta-d-maltotriosyl)glycerol (mal3(phyt)2) as well as a branch-chained phospholipid, diphytanoylphosphatidylcholine (dphpc) were lower than those of straight-chained lipids such as egg yolk phosphatidylcholine (epc) by a factor of approximately 4 at ph 7.0 and 25 degrees c. to examine whether degrees of water penetration and molecular motions in mal3(phyt)2 membranes can account for the lowe ...200111721000
the intein of the thermoplasma a-atpase a subunit: structure, evolution and expression in e. coli.inteins are selfish genetic elements that excise themselves from the host protein during post translational processing, and religate the host protein with a peptide bond. in addition to this splicing activity, most reported inteins also contain an endonuclease domain that is important in intein propagation.200111722801
occurrence of d-amino acids and a pyridoxal 5'-phosphate-dependent aspartate racemase in the acidothermophilic archaeon, thermoplasma acidophilum.free d-amino acid content in some archaea was investigated and d-forms of several amino acids were found in them. in the acidothermophilic archaeon, thermoplasma acidophilum, the proportion of d-aspartate (d-asp) to total asp was as high as 39.7%. crude extracts of thermoplasma acidophilum had asp-specific racemase activity that was pyridoxal 5'-phosphate (plp)-dependent. the relative insensitivity to a sh-modifying reagent distinguished this activity from those of the plp-independent asp racema ...200111181048
variation in molecular species of polar lipids from thermoplasma acidophilum depends on growth temperature.five types of molecular species of c40 isoprenoid chains, having different numbers of cyclopentane rings, were detected in the ether core lipid of thermoplasma acidophilum. the average cyclization number of the hydrocarbon chains in the lipids increased with increasing growth temperatures.200111214723
mechanosensitive channels in prokaryotes.compared to voltage-dependent or ligand-gated ion channels that have extensively been studied over the last twenty years, there is little knowledge available on structure and function of mechanosensitive (ms) channels that constitute the third major group of ion channels classified according to their gating mechanism. the main purpose of this review is to summarize an area of the ms channel research where major progress has occurred. cloning of mscl and mscs, the ms channels of large and small c ...200111275684
probing stability-activity relationships in the thermophilic proteasome from thermoplasma acidophilum by random mutagenesis.structural perturbations (l65h, v12l/m27t, f35v) generated by random mutation of the beta-subunit were used to probe the relationship between stability and activity in the thermophilic proteasome from thermoplasma acidophilum. the optimum temperature for activity of each mutant (approximately 95 degrees c) remained unchanged; however, each mutant was significantly less stable than the wild type. stability, therefore, is not the factor limiting high-temperature activity. interestingly, mutation l ...200111302500
tricorn protease in bacteria: characterization of the enzyme from streptomyces coelicolor.tricorn protease is believed to act downstream of the proteasome, or of other atp-dependent proteases, cleaving the oligopeptides (mostly 6 to 12 residues) released by them into small peptides (2 to 4 residues), before an array of aminopeptidases finally converts them into free amino acids. hitherto, the occurrence of tricorn protease seemed to be limited to some archaea, but genes encoding tricorn homologs have now been found in several bacterial genomes. among them is streptomyces coelicolor a ...200111347893
identification of the gene that, when mutated, causes the human obesity syndrome bbs4.bardet-biedl syndrome (bbs, mim 209900) is a heterogeneous autosomal recessive disorder characterized by obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation, and hypogenitalism. the disorder is also associated with diabetes mellitus, hypertension, and congenital heart disease. six distinct bbs loci map to 11q13 (bbs1), 16q21 (bbs2), 3p13-p12 (bbs3), 15q22.3-q23 (bbs4), 2q31 (bbs5), and 20p12 (bbs6). although bbs is rare in the general population (<1/100,000), th ...200111381270
phylogenetic analysis of archaeal 16s rrna libraries from the rumen suggests the existence of a novel group of archaea not associated with known methanogens.molecular diversity of rumen archaea was analyzed by pcr amplification and sequencing of two 16s rrna clone libraries prepared from the bovine rumen fluid using two different archaea-specific primer sets. the first library of 19 clones which was generated with primers d30 and d33, produced essentially two groups of sequences, one affiliated with methanomicrobium mobile (21% of clones) and the other -- with the uncultured archaeal sequences from anaerobic digester, which are distantly associated ...200111410351
bacterial origin for the isoprenoid biosynthesis enzyme hmg-coa reductase of the archaeal orders thermoplasmatales and archaeoglobales.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 ...200111420376
diversity of free-living prokaryotes from a deep-sea site at the antarctic polar front.to contribute to the understanding of deep-sea planktonic communities, we explored the prokaryotic diversity of a 3000 m deep site at the antarctic polar front using molecular methods. bacterial 16s rdna-amplified sequences corresponded to the as yet uncultivated groups sar11, within the alpha-proteobacteria, and sar324, within the delta-proteobacteria, as well as to the gamma-proteobacteria, cytophagales, planctomyces, gram-positives, and the group of environmental sequences sar406. among them, ...200111451524
purification, crystallization, and preliminary x-ray diffraction analysis of the tricorn protease hexamer from thermoplasma acidophilum.tricorn protease from thermoplasma acidophilum is a hexameric enzyme; in vivo the hexamers assemble further to form large icosahedral capsids of 14.6 mda. recombinant tricorn protease was purified as an enzymatically active hexamer of 0.72 mda that formed crystals of octahedral morphology under low-ionic-strength conditions. these crystals belong to space group c2 with unit cell dimensions a = 307.5 a, b = 163.2 a, c = 220.9 a, beta = 105.5 degrees and diffract to 2.2-a resolution using high-bri ...200111469880
in vitro assessment of archaeosome stability for developing oral delivery systems.the in vitro stability of archaeosomes made from the total polar lipids of methanosarcina mazei, methanobacterium espanolae or thermoplasma acidophilum, was evaluated under conditions encountered in the human gastrointestinal tract. at acidic ph, multilamellar vesicles (mlv) prepared from t. acidophilum lipids were the most stable, releasing approximately 80, 20, 10 and 5% of encapsulated 14c-sucrose at ph 1.5, 2.0, 2.5 and 6.2, respectively, after 90 min at 37 degrees c. archaeosomes from m. ma ...200010601683
archaeosome vaccine adjuvants induce strong humoral, cell-mediated, and memory responses: comparison to conventional liposomes and alum.ether glycerolipids extracted from various archaeobacteria were formulated into liposomes (archaeosomes) possessing strong adjuvant properties. mice of varying genetic backgrounds, immunized by different parenteral routes with bovine serum albumin (bsa) entrapped in archaeosomes ( approximately 200-nm vesicles), demonstrated markedly enhanced serum anti-bsa antibody titers. these titers were often comparable to those achieved with freund's adjuvant and considerably more than those with alum or c ...200010603368
cysteine biosynthesis pathway in the archaeon methanosarcina barkeri encoded by acquired bacterial genes?the pathway of cysteine biosynthesis in archaea is still unexplored. complementation of a cysteine auxotrophic escherichia coli strain nk3 led to the isolation of the methanosarcina barkeri cysk gene [encoding o-acetylserine (thiol)-lyase-a], which displays great similarity to bacterial cysk genes. adjacent to cysk is an open reading frame orthologous to bacterial cyse (serine transacetylase) genes. these two genes could account for cysteine biosynthesis in this archaeon. analysis of recent geno ...200010613873
identification of and spatio-temporal differences between microbial assemblages from two neighboring sulfurous lakes: comparison by microscopy and denaturing gradient gel electrophoresis.the microbial assemblages of lake cisó and lake vilar (banyoles, northeast spain) were analyzed in space and time by microscopy and by performing pcr-denaturing gradient gel electrophoresis (dgge) and sequence analysis of 16s rrna gene fragments. samples obtained from different water depths and at two different times of the year (in the winter during holomixis and in the early spring during a phytoplankton bloom) were analyzed. although the lakes have the same climatic conditions and the same wa ...200010653710
kinetics and mechanism of the citrate synthase from the thermophilic archaeon thermoplasma acidophilum.the kinetics and mechanism of the citrate synthase from a moderate thermophile, thermoplasma acidophilum (tpcs), are compared with those of the citrate synthase from a mesophile, pig heart (pcs). all discrete steps in the mechanistic sequence of pcs can be identified in tpcs. the catalytic strategies identified in pcs, destabilization of the oxaloacetate substrate carbonyl and stabilization of the reactive species, acetyl-coa enolate, are present in tpcs. conformational changes, which allow the ...200010694395
monomolecular organization of the main tetraether lipid from thermoplasma acidophilum at the water-air interface.the monomolecular organization of the main tetraether phospholipid from the archaeon thermoplasma acidophilum was studied by means of a langmuir film balance integrated into a fluorescence microscope. after transfer to solid surfaces at different pressures the films were further investigated by ellipsometry, small angle x-ray scattering and atomic force microscopy. in order to complete former results about the main tetraether phospholipid of t. acidophilum [strobl, c., six, l., heckmann, k., hen ...200010727112
protein purification by ultrafiltration using a beta-galactosidase fusion tag.the use of beta-galactosidase (465 kda) as a fusion tag for ultrafiltration-based protein purification has been investigated. the target protein studied was thermophilic glucose dehydrogenase (157 kda, gdh) from thermoplasma acidophilum. an expression vector was constructed comprising the lacz gene fused to a factor xa cleavage sequence that was attached to the 5' end of the gdh gene. this gene fusion was expressed in escherichia coli jm109 to yield a soluble protein that exhibited activities fo ...200010753458
conformational rearrangements of an archaeal chaperonin upon atpase cycling.chaperonins are double-ring protein assemblies with a central cavity that provides a sequestered environment for in vivo protein folding. their reaction cycle is thought to consist of a nucleotide-regulated alternation between an open substrate-acceptor state and a closed folding-active state. the cavity of atp-charged group i chaperonins, typified by escherichia coli groel [1], is sealed off by a co-chaperonin, whereas group ii chaperonins--the archaeal thermosome and eukaryotic tric/cct [2]--p ...200010753750
glucosylcaldarchaetidylglycerol, a minor phosphoglycolipid from thermoplasma acidophilum.a novel phosphoglycolipid (gpl-k) was isolated from thermoplasma acidophilum (atcc 27658). the chemical components of gpl-k were analyzed by gas liquid chromatography and gc-ms. the sugar moiety of gpl-k and its anomeric region were analyzed by nmr assignment. the core lipid of gpl-k was caldarchaeol, and its main hydrocarbon chains were acyclic and monocyclic c(40) biphytanyl. the polar head groups were alpha-glucose and glycerophosphate. the negative fab-ms spectrum of gpl-k confirmed that the ...200010760458
drg represents a family of two closely related gtp-binding proteins.in a previous publication we identified a novel human gtp-binding protein that was related to drg, a developmentally regulated gtp-binding protein from the central nervous system of mouse. here we demonstrate that both the human and the mouse genome possess two closely related drg genes, termed drg1 and drg2. the two genes share 62% sequence identity at the nucleotide and 58% identity at the protein level. the corresponding proteins appear to constitute a separate family within the superfamily o ...200010760581
why does threonine, and not serine, function as the active site nucleophile in proteasomes?proteasomes belong to the n-terminal nucleophile group of amidases and function through a novel proteolytic mechanism, in which the hydroxyl group of the n-terminal threonines is the catalytic nucleophile. however, it is unclear why threonine has been conserved in all proteasomal active sites, because its replacement by a serine in proteasomes from the archaeon thermoplasma acidophilum (t1s mutant) does not alter the rates of hydrolysis of suc-llvy-amc (seemüller, e., lupas, a., stock, d., lowe, ...200010809725
ferroplasma acidiphilum gen. nov., sp. nov., an acidophilic, autotrophic, ferrous-iron-oxidizing, cell-wall-lacking, mesophilic member of the ferroplasmaceae fam. nov., comprising a distinct lineage of the archaea.an isolate of an acidophilic archaeon, strain yt, was obtained from a bioleaching pilot plant. the organism oxidizes ferrous iron as the sole energy source and fixes inorganic carbon as the sole carbon source. the optimal ph for growth is 1.7, although growth is observed in the range ph 1.3 to 2.2. the cells are pleomorphic and without a cell wall. 16s rrna gene sequence analysis showed this strain to cluster phylogenetically within the order 'thermoplasmales' sensu woese, although with only 89. ...200010843038
conservation of substructures in proteins: interfaces of secondary structural elements in proteasomal subunits.it is observed that during divergent evolution of two proteins with a common phylogenetic origin, the structural similarity of their backbones is often preserved even when the sequence similarity between them decreases to a virtually undetectable level. here we analyzed, whether the conservation of structure along evolution involves also the local atomic structures in the interfaces between secondary structural elements. we have used as study case one protein family, the proteasomal subunits, fo ...200010843865
the chimeric eukaryote: origin of the nucleus from the karyomastigont in amitochondriate protists.we present a testable model for the origin of the nucleus, the membrane-bounded organelle that defines eukaryotes. a chimeric cell evolved via symbiogenesis by syntrophic merger between an archaebacterium and a eubacterium. the archaebacterium, a thermoacidophil resembling extant thermoplasma, generated hydrogen sulfide to protect the eubacterium, a heterotrophic swimmer comparable to spirochaeta or hollandina that oxidized sulfide to sulfur. selection pressure for speed swimming and oxygen avoi ...200010860956
atpase cycle of an archaeal chaperonin.recent structural data imply differences in allosteric behavior of the group i chaperonins, typified by groel from escherichia coli, and the group ii chaperonins, which comprise archaeal thermosome and eukaryotic tric/cct. therefore, this study addresses the mechanism of interaction of adenine nucleotides with recombinant alpha-only and native alphabeta-thermosomes from thermoplasma acidophilum, which also enables us to analyze the role of the heterooligomeric composition of the natural thermoso ...200010864508
atpase cycle controls the conformation of an archaeal chaperonin as visualized by cryo-electron microscopy.chaperonins are double-ring protein folding machines fueled by atp binding and hydrolysis. conformational rearrangements upon atpase cycling of the group i chaperonins, typified by the escherichia coli groel/groes system, have been thoroughly investigated by cryo-electron microscopy and x-ray crystallography. for archaeal group ii chaperonins, however, these methods have so far failed to provide a correlation between the structural and the functional states. here, we show that the conformation o ...200010908735
distribution and diversity of archaea corresponding to the limnological cycle of a hypersaline stratified lake (solar lake, sinai, egypt).the vertical and seasonal distribution and diversity of archaeal sequences was investigated in a hypersaline, stratified, monomictic lake, solar lake, sinai, egypt, during the limnological development of stratification and mixing. archaeal sequences were studied via phylogenetic analysis of 16s rdna sequences as well as denaturing gradient gel electrophoresis analysis. the 165 clones studied were grouped into four phylogenetically different clusters. most of the clones isolated from both the aer ...200010919780
crystal structure of the beta-apical domain of the thermosome reveals structural plasticity in the protrusion region.the crystal structure of the beta-apical domain of the thermosome, an archaeal group ii chaperonin from thermoplasma acidophilum, has been determined at 2.8 a resolution. the structure shows an invariant globular core from which a 25 a long protrusion emanates, composed of an elongated alpha-helix (h10) and a long extended stretch consisting of residues glub245-thrb253. a comparison with previous apical domain structures reveals a large segmental displacement of the protruding part of helix h10 ...200010926489
the effect of valine substitution for glycine in the dimer interface of citrate synthase from thermoplasma acidophilum on stability and activity.to determine the role of hydrophobic interactions in the dimer interface of citrate synthase (cs) from thermoplasma (tp) acidophilum in thermostabilization, we have used site-directed mutagenesis to replace gly 196 by val on the helix l of the subunit interface. recombinant wild-type and gly 196 mutant tpcs enzymes were largely identical in terms of substrate specificities (k(m) for oxaloacetate and acetyl coa). however, the mutation not only reduced catalytic activity (about 10-fold) (i.e., v(m ...200010964687
cloning and characterization of ftsz and pyrf from the archaeon thermoplasma acidophilum.to characterize cytoskeletal components of archaea, the ftsz gene from thermoplasma acidophilum was cloned and sequenced. in t. acidophilum ftsz, which is involved in cell division, was found to be in an operon with the pyrf gene, which encodes orotidine-5'-monophosphate decarboxylase (odc), an essential enzyme in pyrimidine biosynthesis. both ftsz and pyrf from t. acidophilum were expressed in escherichia coli and formed functional proteins. ftsz expression in wild-type e. coli resulted in the ...200010973825
use your neighbour's genes. 200011028987
the genome sequence of the thermoacidophilic scavenger thermoplasma acidophilum.thermoplasma acidophilum is a thermoacidophilic archaeon that thrives at 59 degrees c and ph 2, which was isolated from self-heating coal refuse piles and solfatara fields. species of the genus thermoplasma do not possess a rigid cell wall, but are only delimited by a plasma membrane. many macromolecular assemblies from thermoplasma, primarily proteases and chaperones, have been pivotal in elucidating the structure and function of their more complex eukaryotic homologues. our interest in protein ...200011029001
giant vesicles from 72-membered macrocyclic archaeal phospholipid analogues: initiation of vesicle formation by molecular recognition between membrane componentsstereochemically pure archeal acyclic bola-amphiphilic diphosphates 4 and 5, with the basic structure of the phospholipids found in sulfolobus, have been synthesized for the first time. the self-assembly properties have been compared with those of the nearly identical 72-membered macrocyclic tetraether phosphates 3a and 3b, analogues of the major phospholipid components of sulfolobus, thermoplasma, and methanogenic archea, which were also synthesized. phase contrast and fluorescence microscopies ...200011039526
pan, the proteasome-activating nucleotidase from archaebacteria, is a protein-unfolding molecular chaperone.the proteasome-activating nucleotidase (pan) from methanococcus jannaschii is a complex of relative molecular mass 650,000 that is homologous to the atpases in the eukaryotic 26s proteasome. when mixed with 20s archaeal proteasomes and atp, pan stimulates protein degradation. here we show that pan reduces aggregation of denatured proteins and enhances their refolding. these processes do not require atp hydrolysis, although atp binding enhances the ability of pan to prevent aggregation. pan also ...200011056539
thermostability and thermoactivity of citrate synthases from the thermophilic and hyperthermophilic archaea, thermoplasma acidophilum and pyrococcus furiosus.citrate synthases from thermoplasma acidophilum (optimal growth at 55 degrees c) and pyrococcus furiosus (100 degrees c) are homo-dimeric enzymes that show a high degree of structural homology with each other, and thermostabilities commensurate with the environmental temperatures in which their host cells are found. a comparison of their atomic structures with citrate synthases from mesophilic and psychrophilic organisms has indicated the potential importance of inter-subunit contacts for thermo ...200011099387
characterization of caldarchaetidylglycerol analogs, dialkyl-type and trialkyl-type, from thermoplasma acidophilum.the structures of three kinds of phospholipids (pl-x, pl-y, and pl-t) isolated from thermoplasma acidophilum have been characterized. the core lipid of pl-y was caldarchaeol, and that of pl-x was archaeol. the composition of the hydrocarbon chains of the pl-t core lipid was c20 phytane and c40 isoprenoid in a molar ratio of 2 to 1. the major molecular species of the c40 isoprenoid was acyclic without the cyclopentane ring. these three kinds of intact phospholipids commonly had glycerophosphate r ...200011104022
horizontal transfer of archaeal genes into the deinococcaceae: detection by molecular and computer-based approaches.members of the deinococcaceae (e.g., thermus, meiothermus, deinococcus) contain a/v-atpases typically found in archaea or eukaryotes which were probably acquired by horizontal gene transfer. two methods were used to quantify the extent to which archaeal or eukaryotic genes have been acquired by this lineage. screening of a meiothermus ruber library with probes made against thermoplasma acidophilum dna yielded a number of clones which hybridized more strongly than background. one of these contain ...200011116332
archaeal adaptation to higher temperatures revealed by genomic sequence of thermoplasma volcanium.the complete genomic sequence of the archaeon thermoplasma volcanium, possessing optimum growth temperature (ogt) of 60 degrees c, is reported. by systematically comparing this genomic sequence with the other known genomic sequences of archaea, all possessing higher ogt, a number of strong correlations have been identified between characteristics of genomic organization and the ogt. with increasing ogt, in the genomic dna, frequency of clustering purines and pyrimidines into separate dinucleotid ...200011121031
rotary and unidirectional metal shadowing of vat: localization of the substrate-binding domain.aaa-atpases have important roles in manifold cellular processes. vat (valosine-containing protein-like atpase of thermoplasma acidophilum), a hexameric archaeal member of this family, has the tripartite domain structure n-d1-d2 that is characteristic of many members of this family. n, the n-terminal domain of 20.5 kda, has been implicated in substrate binding. we have applied rotary and unidirectional shadowing to vat and an n-terminally deleted mutant, vat(delta n), in order to map the location ...200011162738
structure of the aaa atpase p97.p97, an abundant hexameric atpase of the aaa family, is involved in homotypic membrane fusion. it is thought to disassemble snare complexes formed during the process of membrane fusion. here, we report two structures: a crystal structure of the n-terminal and d1 atpase domains of murine p97 at 2.9 a resolution, and a cryoelectron microscopy structure of full-length rat p97 at 18 a resolution. together, these structures show that the d1 and d2 hexamers pack in a tail-to-tail arrangement, and that ...200011163219
extreme genomes.the complete genome sequence of thermoplasma acidophilum, an acid- and heat-loving archaeon, has recently been reported. comparative genomic analysis of this 'extremophile' is providing new insights into the metabolic machinery, ecology and evolution of thermophilic archaea.200011178269
discontinuous occurrence of the hsp70 (dnak) gene among archaea and sequence features of hsp70 suggest a novel outlook on phylogenies inferred from this protein.occurrence of the hsp70 (dnak) gene was investigated in various members of the domain archaea comprising both euryarchaeotes and crenarchaeotes and in the hyperthermophilic bacteria aquifex pyrophilus and thermotoga maritima representing the deepest offshoots in phylogenetic trees of bacterial 16s rrna sequences. the gene was not detected in 8 of 10 archaea examined but was found in a. pyrophilus and t. maritima, from which it was cloned and sequenced. comparative analyses of the hsp70 amino aci ...19999882656
allosteric control of three b12-dependent (class ii) ribonucleotide reductases. implications for the evolution of ribonucleotide reduction.three separate classes of ribonucleotide reductases are known, each with a distinct protein structure. one common feature of all enzymes is that a single protein generates each of the four deoxyribonucleotides. class i and iii enzymes contain an allosteric substrate specificity site capable of binding effectors (atp or various deoxyribonucleoside triphosphates) that direct enzyme specificity. some (but not all) enzymes contain a second allosteric site that binds only atp or datp. binding of datp ...199910066778
high-resolution afm-imaging and mechanistic analysis of the 20 s proteasome.as macromolecular protease complex, the 20 s proteasome is responsible for the degradation of cellular proteins and the generation of peptide epitopes for antigen presentation. here, structural and functional aspects of the 20 s proteasome from thermoplasma acidophilum have been investigated by atomic force microscopy (afm) and surface plasmon resonance (spr). due to engineered histidine tags introduced at defined positions, the proteasome complex was pre-oriented at ultra-flat chelator lipid me ...199910329196
structure of vat, a cdc48/p97 atpase homologue from the archaeon thermoplasma acidophilum as studied by electron tomography.valosine-containing protein-like atpase from thermoplasma acidophilum is a member of the superfamily of atpases associated with a diversity of cellular activities and is closely related to cdc48 from yeast and p97 from higher eukaryotes and more distantly to n-ethylmaleimide-sensitive fusion protein. we have used electron tomography to obtain low-resolution (2-2.5 nm) three-dimensional maps of both the whole 500 kda complex and the n-terminally truncated valosine-containing protein-like atpase f ...199910356978
3d reconstruction of the atp-bound form of cct reveals the asymmetric folding conformation of a type ii chaperonin.the type ii chaperonin cct (chaperonin containing tcp-1) of eukaryotic cytosol is a heteromeric 16-mer particle composed of eight different subunits. three-dimensional reconstructions of apo-cct and atp-cct have been obtained at 28 a resolution by cryo-electron microscopy. binding of atp generates an asymmetric particle; one ring has a slightly different conformation from the apo-cct ring, while the other has undergone substantial movements in the apical domains. upon atp binding the apical doma ...199910404219
structural conservation of the isolated zinc site in archaeal zinc-containing ferredoxins as revealed by x-ray absorption spectroscopic analysis and its evolutionary implications.the zfx gene encoding a zinc-containing ferredoxin from thermoplasma acidophilum strain ho-62 was cloned and sequenced. it is located upstream of two genes encoding an archaeal homolog of nascent polypeptide-associated complex alpha subunit and a trna nucleotidyltransferase. this gene organization is not conserved in several euryarchaeoteal genomes. the multiple sequence alignments of the zfx gene product suggest significant sequence similarity of the ferredoxin core fold to that of a low potent ...199910438486
isolation and characterization of novel neutral glycolipids from thermoplasma acidophilum.several novel neutral glycolipids (gl-1a, gl-1b, gl-2a, gl-2b and gl-2c) were isolated from thermoplasma acidophilum by high-performance liquid chromatography using phenylboronic acid-silica and preparative thin-layer chromatography. the tentative structures of these lipids were characterized by the combination of gas-liquid chromatography, the methylation procedure, and (1)h-nmr and fab-mass spectrometries. the lipophilic portion of the neutral glycolipids was composed of a simple molecular spe ...199910446424
giant proteases: beyond the proteasome.proteasomes and related proteases are thought to be the principal machinery responsible for intracellular protein degradation. a new class of giant proteases has been discovered that can augment the catabolic functions of proteasomes and, under some conditions, may even substitute for proteasomes altogether.199910469553
an archaebacterial atpase, homologous to atpases in the eukaryotic 26 s proteasome, activates protein breakdown by 20 s proteasomes.in eukaryotes, the 20 s proteasome is the proteolytic core of the 26 s proteasome, which degrades ubiquitinated proteins in an atp-dependent process. archaebacteria lack ubiquitin and 26 s proteasomes but do contain 20 s proteasomes. many archaebacteria, such as methanococcus jannaschii, also contain a gene (s4) that is highly homologous to the six atpases in the 19 s (pa700) component of the eukaryotic 26 s proteasome. to test if this putative atpase may regulate proteasome function, we express ...199910473546
archaeal genomics.four euryarchaeal genomes have been completely sequenced and are publicly available: methanococcus jannaschii, methanobacterium thermoautotrophicum, pyrococcus horikoshii and archaeoglobus fulgidus. four more genome sequences, two crenarchaeal and two pyrococci, will soon be released. in addition, seven more archaeal genome sequencing projects are under way, including two halophiles, two thermoplasma, and a methanogen. these projects cover all branches of the archaeal domain and will lead to new ...199910508726
beta-propeller repeats and a pdz domain in the tricorn protease: predicted self-compartmentalisation and c-terminal polypeptide-binding strategies of substrate selection.prokaryotic proteases demonstrate a variety of substrate-selection strategies that prevent uncontrolled protein degradation. proteasomes and clpxp-like proteases form oligomeric structures that exclude large substrates from central solvated chambers containing their active sites. monomeric prolyl oligopeptidases have been shown to contain beta-propeller structures that similarly reduce access to their catalytic residues. by contrast, tsp-like enzymes contain pdz domains that are thought to speci ...199910518749
the solution structure of vat-n reveals a 'missing link' in the evolution of complex enzymes from a simple betaalphabetabeta element.the vat protein of the archaebacterium thermoplasma acidophilum, like all other members of the cdc48/p97 family of aaa atpases, has two atpase domains and a 185-residue amino-terminal substrate-recognition domain, vat-n. vat shows activity in protein folding and unfolding and thus shares the common function of these atpases in disassembly and/or degradation of protein complexes.199910531028
the import pathway of human and thermoplasma 20s proteasomes into hela cell nuclei is different from that of classical nls-bearing proteins.wild-type proteasomes of human erythrocytes and the archaeon thermoplasma acidophilum compete with each other for transport into nuclei of digitonin-permeabilized hela cells in the presence of an energy-regenerating system and rabbit reticulocyte lysate. 'nls'-mutated thermoplasma proteasomes were also able to compete with human proteasomes in the same assay, although with lower efficiency. furthermore, in contrast to the other archaeal and bacterial cell lysates tested, the thermoplasma cytosol ...199910595581
capsids of tricorn protease studied by electron cryomicroscopy.tricorn protease from the archaeon thermoplasma acidophilum acts "downstream" of the proteasome; in conjunction with its aminopeptidase cofactors it converts peptides generated by the proteasome into free amino acids. the basic functional unit of tricorn is a homohexamer of the 121-kda subunit, 20 of which can assemble further to form an icosahedral capsid with a molecular mass of 14.6 mda. we have used electron cryomicroscopy to determine the structure of the tricorn capsids to a resolution of ...199910600560
conformational constraints for protein self-cleavage in the proteasome.the proteasome is the central enzyme of protein degradation in the cytosol and the nucleus. it is involved in the removal of abnormal, misfolded or incorrectly assembled proteins, in the processing or degradation of transcriptional regulators in stress response, in degradation of cyclins in cell-cycle control, in the destruction of transcription factors or metabolic enzymes in cell differentiation and metabolic response, and in mhc class i mediated cellular immune response. by the analysis of th ...19989642094
range of sizes of peptide products generated during degradation of different proteins by archaeal proteasomes.the 20 s proteasome processively degrades cell proteins to peptides. information on the sizes and nature of these products is essential for understanding the proteasome's degradative mechanism, the subsequent steps in protein turnover, and major histocompatibility complex class i antigen presentation. using proteasomes from thermoplasma acidophilum and four unfolded polypeptides as substrates (insulin-like growth factor, lactalbumin, casein, and alkaline phosphatase, whose lengths range from 71 ...19989442034
characterization of homo-oligomeric complexes of alpha and beta chaperonin subunits from the acidothermophilic archaeon, sulfolobus sp. strain 7.the chaperonin from the acidothermophilic archaeon, sulfolobus sp. strain 7, is composed of two kinds of subunits designated as scp alpha and scp beta. in this study, we characterized the recombinant scp alpha and scp beta, which were separately expressed in escherichia coli. both of them were able to assemble to homo-oligomeric double-ring complexes, similar to subunits of group ii chaperonins from thermoplasma acidophilum and thermococcus strain ks-1. both complexes have no or at most trace at ...19989464270
lateral diffusion of the total polar lipids from thermoplasma acidophilum in multilamellar liposomes.31p nmr lineshapes of multilamellar liposomes composed mostly of a bilayer-spanning tetraether lipid are consistent with rapid axially symmetric motion about the bilayer normal. the residual chemical shift anisotropy of 36 ppm is comparable to that seen for diacylphosphatidylglycerol systems and suggests comparable headgroup motion. the lateral diffusion rates for thermoplasma acidophilum total polar lipids in mutilamellar liposomes was measured by two dimensional exchange nmr as a function of t ...19989518643
proteasome function is dispensable under normal but not under heat shock conditions in thermoplasma acidophilum.hitherto the biology of proteolysis in prokaryotes, particularly in archaea, is only poorly understood. we have used the tri-peptide vinyl sulfone inhibitor carboxybenzyl-leucyl-leucyl-leucine vinyl sulfone (z-l3vs) to study the in vivo function of proteasomes in thermoplasma acidophilum. z-l3vs is a potent inhibitor of the thermoplasma proteasome and is capable of modifying 75 to 80% of the proteasomal beta-subunits in cell cultures. inhibition of proteasomes has only marginal effects under nor ...19989541012
a proteolytic system that compensates for loss of proteasome function.proteolysis is essential for the execution of many cellular functions. these include removal of incorrectly folded or damaged proteins, the activation of transcription factors, the ordered degradation of proteins involved in cell cycle control, and the generation of peptides destined for presentation by class i molecules of the major histocompatibility complex. a multisubunit protease complex, the proteasome, accomplishes these tasks. here we show that in mammalian cells inactivation of the prot ...19989560160
citrate synthase and 2-methylcitrate synthase: structural, functional and evolutionary relationships.following the complete sequencing of the escherichia coli genome, it has been shown that the proposed second citrate synthase of this organism, recently described by the authors, is in fact a 2-methylcitrate synthase that possesses citrate synthase activity as a minor component. whereas the hexameric citrate synthase is constitutively produced, the 2-methylcitrate synthase is induced during growth on propionate, and the catabolism of propionate to succinate and pyruvate via 2-methylcitrate is pr ...19989579066
cloning and overexpression in escherichia coli of the gene encoding citrate synthase from the hyperthermophilic archaeon sulfolobus solfataricus.the citrate synthase (cs) gene from the hyperthermophilic archaeon sulfolobus solfataricus has been cloned and sequenced. the gene encodes a polypeptide of 378 amino acids with a calculated polypeptide molecular mass of 42679. high-level expression was achieved in escherichia coli and the recombinant citrate synthase was purified to homogeneity using a heat step and dye-ligand affinity chromatography. this procedure yielded approximately 26 mg of pure cs per liter of culture, with a specific act ...19989672679
amino acid substitutions in the subunit interface enhancing thermostability of thermoplasma acidophilum citrate synthase.we have used citrate synthase from thermoplasma (tp.) acidophilum as a thermostable model system to investigate the role of hydrophobic interactions in dimer interface for maintaining high temperature stability. three mutant enzymes were constructed by single amino acid substitutions in the interface helices: ala97-->ser, ala104-->thr, and gly209-->ala. all of the mutations enhanced the thermostability of tp. citrate synthase, while improving its catalytic properties (km, vmax, and specific acti ...19989712738
the effect of hydrophobic interactions in the dimer interface of thermoplasma acidophilum citrate synthase on thermostability. 19989723739
decelerated degradation of short peptides by the 20s proteasome.based on a twelve residue master peptide comprising all five specific cleavage sites defined for the proteasome, a set of variant peptides was generated in order to probe specificity and to elucidate the mechanism which determines product size. it is shown that the rate of degradation by the 20s proteasome from thermoplasma acidophilum depends critically on the length of the peptide substrate. peptides of 14 residues and longer are degraded much faster than shorter peptides although the sites of ...19989742954
group ii chaperonin in a thermophilic methanogen, methanococcus thermolithotrophicus. chaperone activity and filament-forming ability.a gene encoding 544 amino acids for a subunit of group ii chaperonin (thermosome) was cloned from a thermophilic methanogen, methanococcus thermolithotrophicus. the deduced amino acid sequence showed 66.5, 56.1, and 20.1% similarities to those of methanopyrus kandleri and thermoplasma acidophilum and group i chaperonin of escherichia coli, respectively. we call this chaperonin mtts (m. thermolithotrophicus thermosome). the mtts gene was expressed in e. coli. the purified recombinant mtts seemed ...19989774467
group ii chaperonin in an open conformation examined by electron tomography. 19989783741
novel euryarchaeotal lineages detected on rice roots and in the anoxic bulk soil of flooded rice microcosmsbecause excised, washed roots of rice (oryza sativa) immediately produce ch4 when they are incubated under anoxic conditions (p. frenzel and u. bosse, fems microbiol. ecol. 21:25-36, 1996), we employed a culture-independent molecular approach to identify the methanogenic microbial community present on roots of rice plants. archaeal small-subunit rrna-encoding genes were amplified directly from total root dna by pcr and then cloned. thirty-two archaeal rice root (arr) gene clones were randomly se ...19989835592
the role of tricorn protease and its aminopeptidase-interacting factors in cellular protein degradation.tricorn protease was previously described as the core enzyme of a modular proteolytic system displaying multicatalytic activity. here we elucidate the mode of cooperation between tricorn and its interacting factors, and we identify two additional factors, f2 and f3, closely related aminopeptidases of 89 kda. in conjunction with these three factors, tricorn degrades oligopeptides in a sequential manner, yielding free amino acids. we have been able to reconstitute a proteolytic pathway comprising ...19989845366
the b12-dependent ribonucleotide reductase from the archaebacterium thermoplasma acidophila: an evolutionary solution to the ribonucleotide reductase conundrum.a coenzyme b12-dependent ribonucleotide reductase was purified from the archaebacterium thermoplasma acidophila and partially sequenced. using probes derived from the sequence, the corresponding gene was cloned, completely sequenced, and expressed in escherichia coli. the deduced amino acid sequence shows that the catalytic domain of the b12-dependent enzyme from t. acidophila, some 400 amino acids, is related by common ancestry to the diferric tyrosine radical iron(iii)-dependent ribonucleotide ...19978990160
processive degradation of proteins and other catalytic properties of the proteasome from thermoplasma acidophilum.although the structure of the 20 s proteasome from thermoplasma acidophilum has been elucidated, its enzymatic properties have not been explored in depth. thermoplasma proteasomes, which contain one type of active site, exhibit not only "chymotrypsin-like" activity (as reported), but also some "post-glutamyl" and "trypsin-like" activities. like eukaryotic proteasomes, its activity can be stimulated by sds, mg2+, and also guanidine hcl, but not urea. the enzyme was strongly inhibited by novel pep ...19978999862
subunit topology of the rhodococcus proteasome.the 20s proteasome, isolated from the nocardioform actinomycete rhodococcus erythropolis strain ni86/21, is built from two alpha-type and two beta-type subunits. in order to probe the subunit topology, we have set up an expression system which allows coexpression of the genes encoding the alpha- and beta-subunits in all possible combinations. the four respective constructs obtained yielded fully assembled and proteolytically active proteasomes. biochemical, kinetic and electron microscopy analys ...19979000518
novel zinc-containing ferredoxin family in thermoacidophilic archaea.the dicluster-type ferredoxins from the thermoacidophilic archaea such as thermoplasma acidophilum and sulfolobus sp. are known to contain an unusually long extension of unknown function in the n-terminal region. recent x-ray structural analysis of the sulfolobus ferredoxin has revealed the presence of a novel zinc center, which is coordinated by three histidine ligand residues in the n-terminal region and one aspartate in the ferredoxin core domain. we report here the quantitative metal analyse ...19979013590
identification of beta-l-gulose as the sugar moiety of the main polar lipid thermoplasma acidophilum.the main polar lipid (mpl) of thermoplasma acidophilum has been purified and its structure determined. nmr, mass spectrometry, and capillary gas chromatography-mass spectrometry experiments have shown that the previously unidentified sugar moiety of mpl is the rare sugar l-gulose. mpl is thus a tetraether lipid with cyclopentane rings and head groups of phosphoglycerol, as previously reported, and beta-l-gulopyranose. further, mpl is also the dominant lipid found in lipid extracts from another s ...19979084501
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