| an iron-regulated gene, maga, encoding an iron transport protein of magnetospirillum sp. strain amb-1. | magnetospirillum sp. amb-1 is a freshwater magnetic bacterium which synthesizes intracellular particles of magnetite (fe3o4). a genomic dna fragment required for synthesis of magnetic particles was previously isolated from a nonmagnetic transposon tn5 mutant. we have determined the complete nucleotide sequence of this fragment. the 2975-base pair region contains two putative open reading frames. one open reading frame, designated maga, encodes a polypeptide which is homologous to the cation effl ... | 1995 | 7499342 |
| nitrite reductase from the magnetotactic bacterium magnetospirillum magnetotacticum. a novel cytochrome cd1 with fe(ii):nitrite oxidoreductase activity. | cytochrome cd1 nitrite reductase was isolated from magnetite-containing cells of the magnetotactic bacterium magnetospirillum (formerly aquaspirillum) magnetotacticum, which was microaerobically cultivated under denitrifying conditions. the enzyme showed absorption maxima at 643 nm and 409 nm in the oxidized form, and at 663, 551, 522, and 418 nm in the reduced form. a distinctive split absorption band did not occur at about 550 nm. the pyridine ferrohemochrome spectra suggested the presence of ... | 1995 | 7588814 |
| iron-limited growth and kinetics of iron uptake in magnetospirillum gryphiswaldense. | growth and magnetite formation in magnetospirillum gryphiswaldense msr-1 were found close to the maximum at an extracellular iron concentration of 15-20 microm. ferrous iron was incorporated by a slow, diffusion-like process. several iron chelators including various microbial siderophores were unable to promote transport of iron into the cells. in contrast, spent culture fluids stimulated the uptake of ferric iron in iron-depleted cells at a high rate, whereas fresh medium and transport buffer w ... | 1996 | 8929275 |
| evidence for two types of subunits in the bacterioferritin of magnetospirillum magnetotacticum. | in order to investigate the role of bacterioferritin (bfr) in the biomineralization of magnetite by microorganisms, we have cloned and sequenced the bfr genes from m. magnetotacticum. the organism has two bfr genes that overlap by one nucleotide. both encode putative protein products of 18 kda, the expected size for bfr subunits, and show a strong similarity to other bfr subunit proteins. by scanning the dna sequence databases, we found that a limited number of other organisms, including n. gono ... | 1997 | 9409768 |
| bacterial turgor pressure can be measured by atomic force microscopy. | we report a study of the deformability of a bacterial wall with an atomic force microscope (afm). a theoretical expression is derived for the force exerted by the wall on the cantilever as a function of the depths of indentation generated by the afm tip. evidence is provided that this reaction force is a measure for the turgor pressure of the bacterium. the method was applied to magnetotactic bacteria of the species magnetospirillum gryphiswaldense. force curves were generated on the substrate a ... | 2000 | 11088560 |
| magneto-aerotaxis in marine coccoid bacteria. | magnetotactic cocci swim persistently along local magnetic field lines in a preferred direction that corresponds to downward migration along geomagnetic field lines. recently, high cell concentrations of magnetotactic cocci have been found in the water columns of chemically stratified, marine and brackish habitats, and not always in the sediments, as would be expected for persistent, downward-migrating bacteria. here we report that cells of a pure culture of a marine magnetotactic coccus, design ... | 1997 | 9251816 |
| cloning and sequencing of a gene encoding a new member of the tetratricopeptide protein family from magnetosomes of magnetospirillum magnetotacticum. | a gene encoding the 22 kda protein (mam22) which was localized in the magnetosomes isolated from the magnetotactic bacterium, magnetospirillum magnetotacticum, was cloned and sequenced. mam22 was composed of 220 amino acids (aa) with a molecular weight of 24,186 da. the deduced aa sequence exhibited significant homology with a number of proteins that belong to the tetratricopeptide repeat (tpr) protein family, including mitochondrial protein import receptors and peroxisomal protein import recept ... | 1996 | 8675040 |
| iron-regulated expression and membrane localization of the maga protein in magnetospirillum sp. strain amb-1. | the maga gene from magnetospirillum sp. strain amb-1 is required for the synthesis of bacterial magnetic particles (bmps). this gene has been cloned, sequenced and found to encode a protein which is homologous to the escherichia coli potassium efflux membrane-binding protein, kefc. by using the firefly luciferase gene (luc) cloned downstream of the maga promoter, the effect of iron on regulation of maga expression was investigated, and transcription of maga was found to be enhanced by low concen ... | 1995 | 8537318 |
| purification, and some molecular and enzymatic features of a novel ccb-type cytochrome c oxidase from a microaerobic denitrifier, magnetospirillum magnetotacticum. | a novel ccb-type cytochrome c oxidase was purified from the magnetic bacterium, magnetospirillum magnetotacticum ms-1. the enzyme was composed of three subunits with m(r)'s of 43,000, 34,000 and 28,000, respectively, and contained 0.91 mol of protoheme, 2.0 mol of heme c and 0.70 g atom of copper per mol of minimal structural unit. one mol of enzyme oxidized 187 mol of horse heart ferrocytochrome c and 34.4 mol of m. magnetotacticum ferrocytochrome c550/s. the cytochrome c oxidase activity of th ... | 1994 | 8013655 |
| molecular relationship of an atypical azospirillum strain 4t to other azospirillum species. | dna/dna hybridization, plasmid content and partial 16s rdna sequence were determined to confirm the relationship between two azospirillum strains, 4b and 4t, isolated from the same rice rhizosphere. the partial 16s rdna sequence was determined for 9 strains belonging to 5 azospirillum species which included azospirillum lipoferum strains 4b and 4t, and was compared to a set of ribosomal sequences from other bacteria of the alpha subdivision of the proteobacteria. four azospirillum species sequen ... | 1994 | 7871242 |
| cysteine activation is an inherent in vitro property of prolyl-trna synthetases. | aminoacyl-trna synthetases are well known for their remarkable precision in substrate selection during aminoacyl-trna formation. some synthetases enhance the accuracy of this process by editing mechanisms that lead to hydrolysis of incorrectly activated and/or charged amino acids. prolyl-trna synthetases (prorss) can be divided into two structurally divergent groups, archaeal-type and bacterial-type enzymes. a striking difference between these groups is the presence of an insertion domain (appro ... | 2002 | 12130657 |
| evolutionary relationships among magnetospirillum strains inferred from phylogenetic analysis of 16s rdna sequences. | we have investigated the evolutionary relationships between two facultatively anaerobic magnetospirillum strains (amb-1 and mgt-1) and fastidious, obligately microaerophilic species, such as magnetospirillum magnetotacticum, using a molecular phylogenetic approach. genomic dna from strains mgt-1 and amb-1 was used as a template for amplification of the genes coding for 16s rrna (16s rdna) by the polymerase chain reaction. amplified dna fragments were sequenced (1,424 bp) and compared with sequen ... | 1993 | 7691800 |
| purification, primary structure, and evolution of cytochrome c-550 from the magnetic bacterium, magnetospirillum magnetotacticum. | cytochrome c-550 was purified from magnetospirillum magnetotacticum to an electrophoretically homogeneous state, and some of its properties were determined. the cytochrome showed absorption peaks at 528 and 409 nm in the oxidized form, and at 550, 521, and 414 nm in the reduced form. its midpoint redox potential at ph 7.0 was determined to be +289 mv. the primary structure of cytochrome c-550 was determined. cytochrome c is composed of 97 amino acid residues, and its molecular weight was calcula ... | 1995 | 7575096 |
| phylogenetic relationships of the helical-shaped bacteria in the alpha proteobacteria inferred from 16s rdna sequences. | 16s ribosomal rna gene sequences from seven strains of aquaspirillum peregrinum, aqu. itersonii, aqu. polymorphum, and oceanospirillum pusillum were compared with homologous sequences from other members of helical-shaped bacteria. the bootstrapped neighbor-joining tree, inferred from 887 aligned sites, placed the spirillum taxa assigned to aquaspirillum, oceanospirillum, azospirillum, magnetospirillum, rhodospirillum, and rhodocista of the proteobacteria in seven clusters of alpha proteobacteria ... | 1997 | 12501339 |
| development of a genetic system for magnetospirillum gryphiswaldense. | genetic analysis of bacterial magnetosome biomineralization has been hindered by the lack of an appropriate methodology for cultivation and genetic manipulation of most magnetotactic bacteria. in this report, a genetic system for magnetospirillum gryphiswaldense is described. the system includes a plating technique that allows the screening of magnetic vs non-magnetic colonies, and a protocol for the transfer of foreign dna by electroporation and high-frequency conjugation. various broad-host-ra ... | 2003 | 12560986 |
| phylogeny and 16s rrna sequence of magnetospirillum sp. amb-1, an aerobic magnetic bacterium. | | 1992 | 1549478 |
| a magnetosome-specific gtpase from the magnetic bacterium magnetospirillum magneticum amb-1. | magnetic bacteria produce intracellular vesicles that envelope single domain magnetite crystals. although many proteins are present in this intracellular vesicle membrane, five are specific to this membrane. a 16-kda protein, designated mms16, is the most abundant of the magnetosome-specific proteins, and to establish its function we cloned and sequenced its gene from magnetospirillum magneticum amb-1. this was achieved by determination of the n-terminal amino acid sequence of the protein follow ... | 2001 | 11557762 |
| adverse effects of microgravity on the magnetotactic bacterium magnetospirillum magnetotacticum. | bacteria that contain magnetosomes display magnetotaxis and align themselves to the earth's magnetic field. when magnetotactic bacteria were first isolated several decades ago it was presumed that geomagnetic orientation allowed magnetotactic bacteria to orient themselves downward towards sediments where the habitat is favorable to their growth and metabolism. as more species of magnetotactic bacteria have been isolated and studied, differences in magnetotactic responses have been observed which ... | 2000 | 11543576 |
| effects of growth medium composition, iron sources and atmospheric oxygen concentrations on production of luciferase-bacterial magnetic particle complex by a recombinant magnetospirillum magneticum amb-1. | growth conditions for mass production of luciferase-bacterial magnetic particles (bmps) by a recombinant magnetospirillum magneticum amb-1 were investigated in a ph-regulated fed-batch culture system. enrichment of growth medium with l-cysteine, yeast extract and polypeptone enhanced both bacterial growth and bmp production. the presence of l-cysteine in the medium was useful for induction of cell growth. strict anaerobic conditions led to a prolonged lag phase and limited the final cell density ... | 2001 | 11427230 |
| swimming characteristics of magnetic bacterium, magnetospirillum sp. amb-1, and implications as toxicity measurement. | to develop a novel toxicity measurement system using the persistent swimming property of magnetic bacteria along an externally applied magnetic field, certain characteristics of magnetospirillum sp. amb-1 cells were examined, including their growth pattern, motility, magnetosensitivity, swimming speed, and cell length distribution. in addition, the effect of toxic compounds on the swimming speed was assessed relative to application as a toxicity sensor. with an inoculum of 1.0 x 10(8) cells/ml, ... | 2001 | 11400102 |
| physical and genetic characterization of the genome of magnetospirillum magnetotacticum, strain ms-1. | pulsed-field gel analysis of magnetospirillum magnetotacticum, strain ms-1, indicates that the genome is a single, circular structure of about 4.3 mb. a few genes, identified by sequence similarity, have been localized and arranged in a map with dnaa, indicating the presumed origin of replication. there are at least two rrna operons. in addition, rrna genes are found on a 40 kb, possibly extrachromosomal, structure. the genes thought to be involved in magnetite synthesis, bfr and maga, are locat ... | 2001 | 11250081 |
| expression and characterization of a magnetosome-associated protein, tpr-containing mam22, in escherichia coli. | a magnetosome-associated protein, mam22, contains a tpr domain (five tpr motifs and one putative tpr motif) that has been known to mediate protein-protein interactions. we expressed the mam22 gene in escherichia coli and found that the purified mam22 was reversibly self-aggregated by nacl. the structural model of mam22 which has been proposed on the basis of the crystal structure of the n-terminal tpr domain of a human ser/thr protein phosphatase suggests the novel hydrophobic colloidal features ... | 2001 | 11240121 |
| bacterial and archaeal populations associated with freshwater ferromanganous micronodules and sediments. | biology is believed to play a large role in the cycling of iron and manganese in many freshwater environments, but specific microbial groups indigenous to these systems have not been well characterized. to investigate the populations of bacteria and archaea associated with metal-rich sediments from green bay, wi, we extracted nucleic acids and analysed the phylogenetic relationships of cloned 16s rrna genes. because nucleic acids have not been routinely extracted from metal-rich samples, we inve ... | 2001 | 11225719 |
| n2-dependent growth and nitrogenase activity in the metal-metabolizing bacteria, geobacter and magnetospirillum species. | cells of geobacter metallireducens, magnetospirillum strain amb-1, magnetospirillum magnetotacticum and magnetospirillum gryphiswaldense showed n2-dependent growth, the first anaerobically with fe(iii) as the electron acceptor, and the latter three species microaerobically in semi-solid oxygen gradient cultures. cells of the magnetospirillum species grown with n2 under microaerobic conditions were magnetotactic and therefore produced magnetosomes. cells of geobacter metallireducens reduced acety ... | 2000 | 11200427 |
| heme-copper oxidase family structure of magnetospirillum magnetotacticum 'cytochrome a1'-like hemoprotein without cytochrome c oxidase activity. | the genes encoding 'cytochrome a1'-like hemoprotein of magnetospirillum magnetotacticum were identified and sequenced. three orfs, mcali, mcai and hosa, were included in the sequenced region. the six histidine residues which were predicted to associate with the prosthetic cofactors of heme-copper oxidase superfamily were conserved in the hemoprotein. however, none of the amino acid residues which were proposed to participate in the oxygen-reducing and the coupled proton pumping reactions in cyto ... | 2000 | 11132641 |
| single nucleotide mismatch analysis using oligonucleotide probes synthesized on bacterial magnetic particle. | an approach to analyze mismatches using short and specific oligonucleotide probes directly synthesized on bacterial magnetic particles (bmps) by phosphoramidite methods was exploited. approximately 126 molecules of 4-mer oligonucleotides/particle were synthesized on bmps with high reaction efficiencies. hybridization between fitc-labeled oligonucleotides and chemically synthesized oligonucleotides on bmps was performed. perfect matched and mismatched hybridizations were successfully discriminate ... | 2003 | 12919813 |
| characterization of a spontaneous nonmagnetic mutant of magnetospirillum gryphiswaldense reveals a large deletion comprising a putative magnetosome island. | frequent spontaneous loss of the magnetic phenotype was observed in stationary-phase cultures of the magnetotactic bacterium magnetospirillum gryphiswaldense msr-1. a nonmagnetic mutant, designated strain msr-1b, was isolated and characterized. the mutant lacked any structures resembling magnetosome crystals as well as internal membrane vesicles. the growth of strain msr-1b was impaired under all growth conditions tested, and the uptake and accumulation of iron were drastically reduced under iro ... | 2003 | 13129949 |
| production of luciferase-magnetic particle complex by recombinant magnetospirillum sp. amb-1. | luciferase-bacterial magnetic particle (bmp) complexes were produced by recombinant magnetospirillum sp. amb-1. we constructed plasmids pkml and pnelm, respectively, by fusing luc to the 5' and 3' terminal of maga, encoding an integral iron translocating protein situated in the bmp membrane, of amb-1. in addition, we produced bifunctional active-fusion proteins on bmps by using a plasmid pacml. in this plasmid, acetate kinase and luciferase genes were fused to the n-terminus and the c-terminus o ... | 2000 | 11064341 |
| fully automated chemiluminescence immunoassay of insulin using antibody-protein a-bacterial magnetic particle complexes. | we report a fully automated sandwich immunoassay for the determination of human insulin using antibody-protein a-bacterial magnetic particle (bmp) complexes and an alkaline phosphatase-conjugated secondary antibody. bmps bearing protein a-maga inserted on the external surface of the membrane were prepared in the magnetospirillum sp. amb-1 transconjugant for a protein a-maga fusion gene. maga protein was used as an anchor to attach protein a onto the membrane. protein a-bmp complexes harvested fr ... | 2000 | 10952537 |
| two-dimensional analysis of proteins specific to the bacterial magnetic particle membrane from magnetospirillum sp. amb-1. | we report the identification of five proteins expressed specifically on the bacterial magnetic particle (bmp) membrane of magnetospirillum sp. amb-1. these proteins are major components of the bmp membrane. the molecular weights were determined to be 12.0, 16.0, 24.8, 35.6, and 66.2 kda by sodium dodecyl sulfate polyacrylamide gel electrophoresis. of these five, the 16.0-kda protein was the most abundant in the bmp membrane. furthermore, the 16.0-kda protein consisted of two components each of d ... | 2000 | 10849810 |
| membrane vesicles in magnetotactic bacteria. | magnetotactic bacteria are microorganisms that respond to magnetic fields. we have studied the surface ultrastructure of magnetospirillum magnetotacticum and uncultured magnetotactic bacteria from a marine environment using transmission electron microscopy and freeze-etching. numerous membrane vesicles were observed on the surface of magnetospirillum magnetotacticum bacteria. all uncultured magnetotactic bacteria presented membrane vesicles on their surface in addition to an extensive capsular m ... | 2003 | 14717452 |
| biochemical and proteomic analysis of the magnetosome membrane in magnetospirillum gryphiswaldense. | we analyzed the biochemical composition of the magnetosome membrane (mm) in magnetospirillum gryphiswaldense. isolated magnetosomes were associated with phospholipids and fatty acids which were similar to phospholipids and fatty acids from other subcellular compartments (i.e., outer and cytoplasmic membranes) but were present in different proportions. the binding characteristics of mm-associated proteins were studied by selective solubilization and limited proteolysis. the mm-associated proteins ... | 2004 | 14766587 |
| isolation and characterization of a new denitrifying spirillum capable of anaerobic degradation of phenol. | two kinds of phenol-degrading denitrifying bacteria, azoarcus sp. strain cc-11 and spiral bacterial strain cc-26, were isolated from the same enrichment culture after 1 and 3 years of incubation, respectively. both strains required ferrous ions for growth, but strain cc-26 grew better than strain cc-11 grew under iron-limited conditions, which may have resulted in the observed change in the phenol-degrading bacteria during the enrichment process. strain cc-26 grew on phenol, benzoate, and other ... | 2000 | 10742201 |
| cloning and characterization of a gene, mpsa, encoding a protein associated with intracellular magnetic particles from magnetospirillum sp. strain amb-1. | proteins located within the lipid bilayer, surrounding the intracellular bacterial magnetic particles (bmp) from magnetospirillum sp. amb-1, were separated using sds-page. several major proteins of approximate molecular weight 66.2, 35.6, and 24.8 kda were identified. the n-terminal amino acid sequence of one of these proteins, designated mpsa, was determined and used to design a pair of pcr primers which amplified a 105 bp dna fragment from amb-1 genomic dna. gene-walking, using anchored pcr, w ... | 2000 | 10679308 |
| improved technique for the isolation of magnetotactic spirilla from a freshwater sediment and their phylogenetic characterization. | an improved technique for the isolation of magnetotactic bacteria was used for the axenic cultivation of microaerophilic magnetotactic spirilla. magnetotactic bacteria were first separated from non-magnetic contaminants by exploiting their active migration along magnetic field lines by a capillary "racetrack" method. the purified magnetic cells were then inoculated into a two-layer isolation medium with opposing oxygen and sulfide gradients. several strains of magnetotactic spirilla were isolate ... | 1999 | 10553299 |
| unraveling the function of the rhodospirillum rubrum activator of polyhydroxybutyrate (phb) degradation: the activator is a phb-granule-bound protein (phasin). | efficient hydrolysis of native poly(3-hydroxybutyrate) (nphb) granules in vitro by soluble phb depolymerase of rhodospirillum rubrum requires pretreatment of nphb with an activator compound present in r. rubrum cells (j. m. merrick and m. doudoroff, j. bacteriol. 88:60-71, 1964). edman sequencing of the purified activator (17.4 kda; matrix-assisted laser desorption ionization-time of flight mass spectrometry) revealed identity to a hypothetical protein deduced from a partially sequenced r. rubru ... | 2004 | 15060050 |
| iron reductase for magnetite synthesis in the magnetotactic bacterium magnetospirillum magnetotacticum. | ferric iron reductase was purified from magnetotactic bacterium magnetospirillum (formerly aquaspirillum) magnetotacticum (atcc 31632) to an electrophoretically homogeneous state. the enzyme was loosely bound on the cytoplasmic face of the cytoplasmic membrane and was found more frequently in magnetic cells than in nonmagnetic cells. the molecular mass of the purified enzyme was calculated upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis to be about 36 kda, almost the same as that ... | 1999 | 10094692 |
| assembly of g protein-coupled receptors onto nanosized bacterial magnetic particles using mms16 as an anchor molecule. | g protein-coupled receptors (gpcrs) play a central role in a wide range of biological processes and are prime targets for drug discovery. gpcrs have large hydrophobic domains, and therefore purification of gpcrs from cells is frequently time-consuming and typically results in loss of native conformation. in this work, gpcrs have been successfully assembled into the lipid membrane of nanosized bacterial magnetic particles (bmps) produced by the magnetic bacterium magnetospirillum magneticum amb-1 ... | 2004 | 15128546 |
| dynamics of iron uptake and fe3o4 biomineralization during aerobic and microaerobic growth of magnetospirillum gryphiswaldense. | iron uptake and magnetite (fe3o4) crystal formation could be studied in the microaerophilic magnetic bacterium magnetospirillum gryphiswaldense by using a radioactive tracer method for iron transport and a differential light-scattering technique for magnetism. magnetite formation occurred only in a narrow range of low oxygen concentration, i.e., 2 to 7 microm o2 at 30 degrees c. magnetic cells stored up to 2% iron as magnetite crystals in intracytoplasmic vesicles. this extraordinary uptake of i ... | 1998 | 9422606 |
| biotechnological applications of bioluminescence and chemiluminescence. | recent progress in molecular biology has made available several biotechnological tools that take advantage of the high detectability and rapidity of bioluminescence and chemiluminescence spectroscopy. these developments provide inroads to in vitro and in vivo continuous monitoring of biological processes (e.g. gene expression, protein-protein interaction and disease progression), with clinical, diagnostic and drug discovery applications. furthermore, combining luminescent enzymes or photoprotein ... | 2004 | 15158059 |
| inactivation of the flagellin gene flaa in magnetospirillum gryphiswaldense results in nonmagnetotactic mutants lacking flagellar filaments. | magnetotactic bacteria synthesize magnetosomes, which cause them to orient and migrate along magnetic field lines. the analysis of magnetotaxis and magnetosome biomineralization at the molecular level has been hindered by the unavailability of genetic methods, namely the lack of a means to introduce directed gene-specific mutations. here we report a method for knockout mutagenesis by homologous recombination in magnetospirillum gryphiswaldense. multiple flagellin genes, which are unlinked in the ... | 2004 | 15184166 |
| bacterial alpha2-macroglobulins: colonization factors acquired by horizontal gene transfer from the metazoan genome? | invasive bacteria are known to have captured and adapted eukaryotic host genes. they also readily acquire colonizing genes from other bacteria by horizontal gene transfer. closely related species such as helicobacter pylori and helicobacter hepaticus, which exploit different host tissues, share almost none of their colonization genes. the protease inhibitor alpha2-macroglobulin provides a major metazoan defense against invasive bacteria, trapping attacking proteases required by parasites for suc ... | 2004 | 15186489 |
| a large gene cluster encoding several magnetosome proteins is conserved in different species of magnetotactic bacteria. | in magnetotactic bacteria, a number of specific proteins are associated with the magnetosome membrane (mm) and may have a crucial role in magnetite biomineralization. we have cloned and sequenced the genes of several of these polypeptides in the magnetotactic bacterium magnetospirillum gryphiswaldense that could be assigned to two different genomic regions. except for mama, none of these genes have been previously reported to be related to magnetosome formation. homologous genes were found in th ... | 2001 | 11571158 |
| [an oligonucleotide primer system for amplification of the ribulose-1,5-bisphosphate carboxylase/oxygenase genes of bacteria of various taxonomic groups]. | based on the analysis of genbank nucleotide sequences of the cbbl and cbbm genes, coding for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubpc), the key enzyme of the calvin cycle, a primer system was designed that allows about 800-bp-long fragments of these genes to be pcr-ampliflied in various photo- and chemotrophic bacteria. the efficiency of the designed primer system in detection of rubpc genes was demonstrated in pcr with dna of taxonomically diverse bacteria pos ... | 2004 | 15315232 |
| single nucleotide polymorphism detection in aldehyde dehydrogenase 2 (aldh2) gene using bacterial magnetic particles based on dissociation curve analysis. | single nucleotide polymorphism (snp) detection for aldehyde dehydrogenase 2 (aldh2) gene based on dna thermal dissociation curve analysis was successfully demonstrated using an automated system with bacterial magnetic particles (bmps) by developing a new method for avoiding light scattering caused by nanometer-size particles when using commercially available fluorescent dyes such as fitc, cy3, and cy5 as labeling chromophores. biotin-labeled pcr products in aldh2, two allele-specific probes (cy3 ... | 2004 | 15329927 |
| preparation of luciferase-bacterial magnetic particle complex by artificial integration of maga-luciferase fusion protein into the bacterial magnetic particle membrane. | maga is an iron-translocating protein found in the membranes of magnetic bacterium. luciferase-bacterial magnetic particle (bmp) complexes were prepared by artificially inserting maga-luciferase fusion proteins into the membranes of bmps from magnetospirillum magneticum strain amb-1. fusion proteins were from recombinant escherichia coli membranes. maga-luc fusion proteins were integrated by sonication in vitro. successful integration of fusion proteins was confirmed by luciferase luminescence o ... | 2002 | 11807756 |
| isolation of magnetospirillum magneticum amb-1 mutants defective in bacterial magnetic particle synthesis by transposon mutagenesis. | nonmagnetic mutants of magnetospirillum magneticum amb-1 were recovered following mini-tn5 transposon mutagenesis. transconjugants with kanamycin resistance were obtained at a frequency of 2.7 x 10(-7) per recipient. of 3327 transconjugants, 62 were defective for bacterial magnetic particle (bmp) synthesis. the frequency of independent transposition events for nonmagnetic mutants was about 1.4% in transconjugants. further analysis of dna sequences flanking transposon by inverted polymerase chain ... | 2001 | 11963843 |
| siderophore production of a periplasmic transport binding protein kinase gene defective mutant of magnetospirillum magneticum amb-1. | a non-magnetic mutant, nma61, of the magnetic bacterium magnetospirillum magneticum amb-1 was generated by transposon mutagenesis to identify genes involved in magnetosome synthesis. the genomic region of nma61 interrupted by a mini-tn5 transposon was analyzed. the transposon was inserted in an open reading frame (orf) coding for a periplasmic transport binding protein kinase gene homologue. three adjacent orfs and a promoter were identified upstream, indicating that the sequences comprised an o ... | 2004 | 15381078 |
| synthesis of bacterial magnetic particles during cell cycle of magnetospirillum magneticum amb-1. | we investigated the relationship between the synthesis of bacterial magnetic particles (bmps) and the transcription of maga gene-encoding iron transport protein using synchronous culture of magnetospirillum magneticum amb-1. synchronously cultured cells were subjected to transmission electron microscopic observation and fluorescence in situ hybridization. the average number of bmps slowly increased in the cell with increasing cell size. a sharp increase in bmps occurred just before cell division ... | 2001 | 11963844 |
| a novel protein tightly bound to bacterial magnetic particles in magnetospirillum magneticum strain amb-1. | magnetic bacteria synthesize magnetite crystals with species-dependent morphologies. the molecular mechanisms that control nano-sized magnetite crystal formation and the generation of diverse morphologies are not well understood. from the analysis of magnetite crystal-associated proteins, several low molecular mass proteins tightly bound to bacterial magnetite were obtained from magnetospirillum magneticum strain amb-1. these proteins showed common features in their amino acid sequences, which c ... | 2003 | 12496282 |
| the biomineralization of magnetosomes in magnetospirillum gryphiswaldense. | magnetotactic bacteria (mtb) are major constituents of natural microbial communities in sediments and chemically stratified water columns. the ability of mtb to migrate along magnetic field lines is based on specific intracellular structures, the magnetosomes, which, in most mtb, are nanometer-sized, membrane-bound magnetic particles consisting of the iron mineral magnetite (fe(3)o(4)). a broad diversity of morphological forms has been found in various mtb. the unique characteristics of bacteria ... | 2002 | 12497187 |
| the presumptive magnetosome protein mms16 is a poly(3-hydroxybutyrate) granule-bound protein (phasin) in magnetospirillum gryphiswaldense. | the mms16 protein has been previously found to be associated with isolated magnetosomes from two magnetospirillum strains. a function of this protein as a magnetosome-specific gtpase involved in the formation of intracellular magnetosome membrane vesicles was suggested. here we present a study of the mms16 protein from magnetospirillum gryphiswaldense to clarify its function. insertion-duplication mutagenesis of the mms16 gene did not affect the formation of magnetosome particles but resulted in ... | 2005 | 15774885 |
| dna extraction using bacterial magnetic particles modified with hyperbranched polyamidoamine dendrimer. | a cascading hyperbranched polyamidoamine dendrimer was synthesized on the surface of bacterial magnetite from magnetospirillum magneticum amb-1 to allow enhanced extraction of dna from fluid suspensions. characterization of the synthesis revealed linear doubling of the surface amine charge from generations one through five starting with an amino silane initiator. furthermore, transmission electron microscopy revealed clear dispersion of the single domain magnetite in aqueous solution. the dendri ... | 2003 | 12615391 |
| characterization of aldehyde ferredoxin oxidoreductase gene defective mutant in magnetospirillum magneticum amb-1. | a non-magnetic mutant of magnetospirillum magneticum amb-1, designated as nma21, was generated by mini-tn5 transposon mutagenesis to identify genes involved in bacterial magnetic particle (bmp) synthesis. alignment of the dna sequences flanking the transposon allowed the isolation of an open reading frame (orf2) within an operon consisting of five genes. the amino acid sequence of orf2 showed homology with tungsten-containing aldehyde ferredoxin oxidoreductase (aor) from pyrococcus furiosus (48% ... | 2003 | 12646191 |
| single nucleotide polymorphism genotyping of aldehyde dehydrogenase 2 gene using a single bacterial magnetic particle. | a single nucleotide polymorphism (snp) genotyping for aldehyde dehydrogenase 2 gene (aldh2) has been developed by using a nano-sized magnetic particle, which was synthesized intracellularly by magnetic bacteria. streptavidin-immobilized on bacterial magnetic particles (bmps) were prepared using biotin labeled cross-linkers reacting with the amine group on bmps. aldh2 fragments from genomic dna were amplified using a tritc labeled primer and biotin labeled primer pair, and conjugated onto bmp sur ... | 2003 | 12706576 |
| snp detection in transforming growth factor-beta1 gene using bacterial magnetic particles. | a single nucleotide polymorphism (snp) within the transforming growth factor-beta1 (tgf-beta1) gene was detected by hybridization-based method using bacterial magnetic particles (bmps). tgf-beta1 is commonly associated with a single base change resulting in a leu(10)-->pro (t(869)-->c) polymorphism and is a genetic marker for susceptibility to osteoporosis. short (9 bases) and specific probes were designed to detect snp in tgf-beta1. detection probes were immobilized on bmps using cross-linking ... | 2003 | 12706579 |
| growth and magnetosome formation by microaerophilic magnetospirillum strains in an oxygen-controlled fermentor. | media and growth conditions were optimized for the microaerobic cultivation of magnetospirillum gryphiswaldense in flasks and in a fermentor, resulting in significantly increased cell and magnetosome yields, compared with earlier studies. a reliable method was established for the automatic control of low dissolved oxygen tensions (po(2)) in the fermentor (oxystat). growth and magnetosome formation by m. gryphiswaldense, m. magnetotacticum and magnetospirillum sp. amb-1 were studied at various ox ... | 2003 | 12764570 |
| nitrate reductase from the magnetotactic bacterium magnetospirillum magnetotacticum ms-1: purification and sequence analyses. | we purified the nitrate reductase from the soluble fraction of magnetospirillum magnetotacticum ms-1. the enzyme was composed of 86- and 17-kda subunits and contained molybdenum, non-heme iron, and heme c. these properties are very similar to those of the periplasmic nitrate reductase found in paracoccus pantotrophus. the m. magnetotacticum nap locus was clustered in seven open reading frames, napfdaghbc. the phylogenetic analyses of napa, napb, and napc suggested a close relationship between m. ... | 2003 | 12795406 |
| design and application of a new cryptic-plasmid-based shuttle vector for magnetospirillum magneticum. | a 3.7-kb cryptic plasmid designated pmgt was found in magnetospirillum magneticum mgt-1. it was characterized and used for the development of an improved expression system in strain amb-1 through the construction of a shuttle vector, pumg. an electroporation method for magnetic bacteria that uses the cryptic plasmid was also developed. | 2003 | 12839813 |
| single-nucleotide polymorphism analysis using fluorescence resonance energy transfer between dna-labeling fluorophore, fluorescein isothiocyanate, and dna intercalator, popo-3, on bacterial magnetic particles. | to develop an analytical system for single-nucleotide polymorphisms (snps), the fluorescence resonance energy transfer (fret) technique was employed on a bacterial magnetic particle (bmp) surface. a combination of fluorescein isothiocyanate (fitc; excitation 490 nm/emission 520 nm) labeled at the 5' end of dna and an intercalating compound (popo-3, excitation 534 nm/emission 570 nm) was used to avoid the interference from light scattering caused by nanoparticles. after hybridization between targ ... | 2003 | 12910548 |
| a hypervariable 130-kilobase genomic region of magnetospirillum gryphiswaldense comprises a magnetosome island which undergoes frequent rearrangements during stationary growth. | genes involved in magnetite biomineralization are clustered in the genome of the magnetotactic bacterium magnetospirillum gryphiswaldense. we analyzed a 482-kb genomic fragment, in which we identified an approximately 130-kb region representing a putative genomic "magnetosome island" (mai). in addition to all known magnetosome genes, the mai contains genes putatively involved in magnetosome biomineralization and numerous genes with unknown functions, as well as pseudogenes, and it is particularl ... | 2005 | 16237001 |
| development of efficient expression system for protein display on bacterial magnetic particles. | bacterial magnetic particles (bmps) are utilized for various biomedical applications because they are easily manipulated by magnets, and functional proteins are easily displayed on bmps. to establish highly expressed protein display on bmps, strong promoters were identified using magnetospirillum magneticum amb-1 genome and proteome databases. initially, several proteins highly expressed in amb-1 were identified, and the upstream dna sequences of the open-reading frames were evaluated using a lu ... | 2005 | 16288989 |
| genes and proteins involved in bacterial magnetic particle formation. | magnetic bacteria synthesize intracellular magnetosomes that impart a cellular swimming behaviour referred to as magnetotaxis. the magnetic structures aligned in chains are postulated to function as biological compass needles allowing the bacterium to migrate along redox gradients through the earth's geomagnetic field lines. despite the discovery of this unique group of microorganisms 28 years ago, the mechanisms of magnetic crystal biomineralization have yet to be fully elucidated. this review ... | 2003 | 14607071 |
| development and evaluation of an automated workstation for single nucleotide polymorphism discrimination using bacterial magnetic particles. | we designed an automated workstation for magnetic particle-based single nucleotide polymorphism (snp) discrimination of aldh genotypes. bacterial magnetic particles (bmps) extracted from magnetospirillum magneticum amb-1 were used as dna carriers. the principle for snp discrimination in this study was based on fluorescence resonance energy transfer (fret) between fitc (donor) and popo-3 (acceptor) bound to double-stranded dna. the workstation is equipped with a 96-way automated pipetter which co ... | 2003 | 14615090 |
| molecular analysis of a subcellular compartment: the magnetosome membrane in magnetospirillum gryphiswaldense. | the ability of magnetotactic bacteria (mtb) to orient and migrate along magnetic field lines is based on magnetosomes, which are membrane-enclosed intracellular crystals of a magnetic iron mineral. magnetosome biomineralization is achieved by a process involving control over the accumulation of iron and deposition of the magnetic particle, which has a specific morphology, within a vesicle provided by the magnetosome membrane. in magnetospirillum gryphiswaldense, the magnetosome membrane has a di ... | 2004 | 14668979 |
| magnetosome vesicles are present before magnetite formation, and mama is required for their activation. | bacterial magnetosomes are intracellular compartments that house highly ordered magnetite crystals. by using magnetospirillum sp. amb-1 as a model system, we show that magnetosome vesicles exist in the absence of magnetite, biomineralization of magnetite proceeds simultaneously in multiple vesicles, and biomineralization proceeds from the same location in each vesicle. the magnetosome-associated protein, mama, is required for the formation of functional magnetosome vesicles and displays a dynami ... | 2004 | 15004275 |
| new insights into the evolutionary history of type 1 rhodopsins. | type 1 (archaeal) rhodopsins and related rhodopsin-like proteins had been described in a few halophile archaea, gamma-proteobacteria, a single cyanobacteria, some fungi, and a green alga. in exhaustive database searches, we detected rhodopsin-related sequences derived not only from additional fungal species but also from organisms belonging to three groups in which opsins had hitherto not been described: the alpha-proteobacterium magnetospirillum magnetotacticum, the cryptomonad alga guillardia ... | 2004 | 15045490 |
| fabrication of optically enhanced zno nanorods and microrods using novel biocatalysts. | we developed a straightforward method to produce hexagonal zno nanorods and microrods using a novel biocatalyst, magnetospirillum magnetotacticum. zno nanorods were synthesized homogeneously on growth substrates when the bacterial catalysts were deposited uniformly on substrates whereas zno microrods were formed when the catalysts were introduced to selective areas of growth substrates using microcontact printing. x-ray diffraction measurements reveal that these zno structures exhibit wurtzite s ... | 2005 | 16433431 |
| cloning and functional analysis of the sequences flanking mini-tn5 in the magnetosomes deleted mutant nm4 of magnetospirillum gryphiswaldense msr-1. | a magnetosome deleted mutant nm4 of magnetospirillum gryphiswaldense msr-1 was generated by mini-tn5 transposon mutagenesis, and a 5045-bp fragment flanking mini-tn5 in nm4 was cloned by anchored pcr. sequencing analysis showed that this fragment involved six putative open reading frames (orfs); the mini-tn5 was inserted into orf4. functional complementary test indicated that the 5045-bp fragment was required for biosynthesis of magnetosomes in m. gryphiswaldense msr-1. the protein encoded by or ... | 2005 | 16483136 |
| rescue of protein splicing activity from a magnetospirillum magnetotacticum intein-like element. | the self-catalytic protein splicing mechanism is mediated by the intein plus the first amino acid following the intein c-terminus (termed the +1 residue). although polymorphisms of conserved residues elsewhere in inteins have been widely reported, no splicing-competent intein has been observed without a ser, thr or cys in this functionally essential +1 position. this residue is the nucleophile in two steps of the protein splicing pathway: ligation of the extein fragments during transesterificati ... | 2004 | 15046582 |
| magnetosome formation in prokaryotes. | | 2004 | 15083157 |
| rapid and sensitive detection of 17beta-estradiol in environmental water using automated immunoassay system with bacterial magnetic particles. | a fully automated immunoassay of 17beta-estradiol (e2) was performed using anti-e2 monoclonal antibody immobilized on bacterial magnetic particles (antie2-bmps) and alkaline phosphatase-conjugated e2 (alp-e2). e2 concentration in environmental water samples was evaluated by decrease in luminescence based on competitive reaction. a linear correlation between the luminescence intensity and e2 concentration was obtained between 0.5 and 5 ppb. the minimum detectable concentration of e2 was 20 ppt. a ... | 2004 | 15129724 |
| genetic clues on the evolution of anaerobic catabolism of aromatic compounds. | | 2004 | 15256545 |
| chemolithoautotrophy in the marine, magnetotactic bacterial strains mv-1 and mv-2. | magnetite-producing magnetotactic bacteria collected from the oxic-anoxic transition zone of chemically stratified marine environments characterized by o2/h2s inverse double gradients, contained internal s-rich inclusions resembling elemental s globules, suggesting they oxidize reduced s compounds that could support autotrophy. two strains of marine magnetotactic bacteria, mv-1 and mv-2, isolated from such sites grew in o2-gradient media with h2s or thiosulfate (s2o3(2-)) as electron sources and ... | 2004 | 15338111 |
| exposure of magnetic bacteria to simulated mobile phone-type rf radiation has no impact on mortality. | the interaction of mobile phone rf emissions with biogenic magnetite in the human brain has been proposed as a potential mechanism for mobile phone bioeffects. this is of particular interest in light of the discovery of magnetite in human brain tissue. previous experiments using magnetite-containing bacteria exposed directly to emissions from a mobile phone have indicated that these emissions might be causing greater levels of cell death in these bacterial populations when compared to sham expos ... | 2003 | 15376948 |
| preliminary evaluation of nanoscale biogenic magnetite-based ferromagnetic transduction mechanisms for mobile phone bioeffects. | ferromagnetic transduction models have been proposed as a potential mechanism for mobile phone bioeffects. these models are based on the coupling of rf and pulsed electromagnetic emissions to biogenic magnetite (fe3o4) present in the human brain via either ferromagnetic resonance or mechanical activation of cellular ion channels. we have tested these models experimentally for the first time using a bacterial analogue (magnetospirillum magnetotacticum) which produces intracellular biogenic magnet ... | 2003 | 15382422 |
| magnetic cell separation using antibody binding with protein a expressed on bacterial magnetic particles. | bacterial magnetic particles (bacmps) are efficient platforms of proteins for surface display systems. in this study, mononuclear cells from peripheral blood were separated using bacmps expressing protein a on the bacmp membrane surface (protein a-bacmps), which were complexed with the fc fragment of anti-mouse igg antibody. the procedure of positive selection involves incubation of mononuclear cells and mouse monoclonal antibodies against different cell surface antigens (cd8, cd14, cd19, cd20) ... | 2004 | 15516111 |
| evolution of different oligomeric glycyl-trna synthetases. | there are two oligomeric types of glycyl-trna synthetases (glyrss) in genome, the alpha2beta2 tetramer and alpha2 dimer. here, we showed that the anticodon-binding domains (abds) of dimeric and tetrameric glyrss are non-homologous, although their catalytic central domains (ccds) are homologous. the dimeric glyrs_abd is fused to the c-terminal of ccd in alpha-subunit, but the tetrameric glyrs_abd is to the c-terminal in beta-subunit during evolution. generally, one species only contains one oligo ... | 2005 | 15733854 |
| siderophore production by the magnetic bacterium magnetospirillum magneticum amb-1. | siderophore production by the magnetic bacterium magnetospirillum magneticum amb-1 is elicited by sufficient iron rather than by iron starvation. in order to clarify this unusual pattern, siderophore production was monitored in parallel to iron assimilation using the chrome azurol sulfonate assay and the ferrozine method respectively. iron concentration lowered approximately five times less than its initial concentration only within 4 h post-inoculation, rendering the medium iron deficient. a co ... | 2003 | 12586419 |
| novel facultative anaerobic acidotolerant telmatospirillum siberiense gen. nov. sp. nov. isolated from mesotrophic fen. | three facultative anaerobic acidotolerant gram-negative motile spirilla strains designated 26-4b1, 26-2 and k-1 were isolated from mesotrophic siberian fen as a component of methanogenic consortia. the isolates were found to grow chemoorganotrophically on several organic acids and glucose under anoxic and low oxygen pressure in the dark, tolerant up to 5kpa of oxygen. at low oxygen supply, faint autotrophic growth on the h(2):co(2) mixture was also observed. all three isolates were able to fix n ... | 2007 | 16876366 |
| a comprehensive view on proteasomal sequences: implications for the evolution of the proteasome. | proteasomes are large multimeric self-compartmentizing proteases, which play a crucial role in the clearance of misfolded proteins, breakdown of regulatory proteins, processing of proteins by specific partial proteolysis, cell cycle control as well as preparation of peptides for immune presentation. two main types can be distinguished by their different tertiary structure: the 20s proteasome and the proteasome-like heat shock protein encoded by heat shock locus v, hslv. usually, each biological ... | 2003 | 12595256 |
| novel detection system for biomolecules using nano-sized bacterial magnetic particles and magnetic force microscopy. | a system for streptavidin detection using biotin conjugated to nano-sized bacterial magnetic particles (bmps) has been developed. bmps, isolated from magnetic bacteria, were used as magnetic markers for magnetic force microscopy (mfm) imaging. the magnetic signal was obtained from a single particle using mfm without application of an external magnetic field. the number of biotin conjugated bmps (biotin-bmps) bound to streptavidin immobilized on the glass slides increased with streptavidin concen ... | 2005 | 16111780 |
| transcriptional organization and regulation of magnetosome operons in magnetospirillum gryphiswaldense. | genes involved in magnetite biomineralization are clustered within the genomic magnetosome island of magnetospirillum gryphiswaldense. their transcriptional organization and regulation were studied by several approaches. cotranscription of genes within the mamab, mamdc, and mms clusters was demonstrated by reverse transcription-pcr (rt-pcr) of intergenic regions, indicating the presence of long polycistronic transcripts extending over more than 16 kb. the transcription start points of the mamab, ... | 2006 | 16957191 |
| anaerobic degradation of aromatic compounds by magnetospirillum strains: isolation and degradation genes. | four magnetospirillum strains degrading toluene, phenol, benzoate, and other aromatic compounds under anaerobic conditions were isolated from denitrifying enrichment cultures. one of the isolates, toluene-degrading strain ts-6, contained genes that are homologous to those encoding benzylsuccinate synthase (bss) and benzoyl-coa reductase (bcr), two key enzymes of anaerobic toluene and benzoate degradation respectively in known denitrifying bacteria. transcription of the genes was confirmed. it wa ... | 2005 | 16116275 |
| defluvicoccus vanus gen. nov., sp. nov., a novel gram-negative coccus/coccobacillus in the 'alphaproteobacteria' from activated sludge. | a novel gram-negative coccus/coccobacillus, strain ben 114(t), growing in tetrads, clusters or aggregates, was isolated from activated sludge by micromanipulation. 16s rrna gene sequence analysis revealed that it belonged to the 'alphaproteobacteria', with no close relatives among cultured bacterial isolates. on the basis of phylogenetic data, this organism is considered to belong to a new genus, defluvicoccus, represented by the species defluvicoccus vanus sp. nov., a name chosen because of the ... | 2005 | 16166717 |
| one channel: open and closed. | structural information about the prokaryotic kirbac3.1 inward rectifier family k(+) channel from magnetospirillum magnetotacticum is reported. these results from two-dimensional electron cryomicroscopy (em) shed light on the gating mechanism of members of the kir channel family. | 2005 | 16216569 |
| two different conformational states of the kirbac3.1 potassium channel revealed by electron crystallography. | potassium channels allow the selective flow of k(+) ions across membranes. in response to external gating signals, the potassium channel can move reversibly through a series of structural conformations from a closed to an open state. 2d crystals of the inwardly rectifying k(+) channel kirbac3.1 from magnetospirillum magnetotacticum have been captured in two distinct conformations, providing "snap shots" of the gating process. analysis by electron cryomicroscopy of these kirbac3.1 crystals has re ... | 2005 | 16216578 |
| molecular mechanism of magnet formation in bacteria. | magnetic bacteria have an ability to synthesize intracellular ferromagnetic crystalline particles consisting of magnetite (fe3o4) or greigite (fe3s4) which occur within a specific size range (50-100 nm). bacterial magnetic particles (bmps) can be distinguished by the regular morphology and the presence of an thin organic membrane enveloping crystals from abiologically formed magnetite. the particle is the smallest magnetic crystal that has a regular morphology within the single domain size. ther ... | 2000 | 16232810 |
| iron feeding optimization and plasmid stability in production of recombinant bacterial magnetic particles by magnetospirillum magneticum amb-1 in fed-batch culture. | the production of bacterial magnetic particles (bmps) by recombinant magnetospirillum magneticum amb-1 harboring the plasmid pkml was enhanced in ph-regulated fed-batch culture. the addition of fresh nutrients was feedback-controlled as a function of the ph of the culture. the yield of bmps was optimized by adjusting the rate of ferric iron addition. feeding ferric quinate at 15.4 microg/min resulted ina bmp yield of 7.5 mg/l, which is the highest yield so far reported. expression of a plasmid-e ... | 2001 | 16232977 |
| an acidic protein aligns magnetosomes along a filamentous structure in magnetotactic bacteria. | magnetotactic bacteria are widespread aquatic microorganisms that use unique intracellular organelles to navigate along the earth's magnetic field. these organelles, called magnetosomes, consist of membrane-enclosed magnetite crystals that are thought to help to direct bacterial swimming towards growth-favouring microoxic zones at the bottom of natural waters. questions in the study of magnetosome formation include understanding the factors governing the size and redox-controlled synthesis of th ... | 2006 | 16299495 |
| complete genome sequence of the facultative anaerobic magnetotactic bacterium magnetospirillum sp. strain amb-1. | magnetospirillum sp. strain amb-1 is a gram-negative alpha-proteobacterium that synthesizes nano-sized magnetites, referred to as magnetosomes, aligned intracellularly in a chain. the potential of this nano-sized material is growing and will be applicable to broad research areas. it has been expected that genome analysis would elucidate the mechanism of magnetosome formation by magnetic bacteria. here we describe the genome of magnetospirillum sp. amb-1 wild type, which consists of a single circ ... | 2005 | 16303747 |
| magnetosomes are cell membrane invaginations organized by the actin-like protein mamk. | magnetosomes are membranous bacterial organelles sharing many features of eukaryotic organelles. using electron cryotomography, we found that magnetosomes are invaginations of the cell membrane flanked by a network of cytoskeletal filaments. the filaments appeared to be composed of mamk, a homolog of the bacterial actin-like protein mreb, which formed filaments in vivo. in a mamk deletion strain, the magnetosome-associated cytoskeleton was absent and individual magnetosomes were no longer organi ... | 2006 | 16373532 |
| expression level of heterologous tat genes is crucial for in vivo reconstitution of a functional tat translocase in escherichia coli. | the tat system has the remarkable capacity of exporting proteins in folded conformation across the cytoplasmic membrane. the functional tat translocase from gram-negative bacteria consists of tata, tatb and tatc proteins. to gain information about the species specificity of the tat translocase, we cloned tat genes from gram-negative pathogens shigella flexneri 2a str. 301, vibrio cholerae el tor n16961, pseudomonas aeruginosa pao1, thermophilic sulfolobus solfataricus p2, thermus thermophilus hb ... | 2007 | 17336443 |
| fluorescent bacterial magnetic nanoparticles as bimodal contrast agents. | the purpose of this study was to assess whether fluorochrome-coupled bacterial magnetic nanoparticles can be used as bimodal contrast agent for both magnetic resonance imaging (mri) and near-infrared fluorescence optical (nirf) imaging of cultured macrophages. | 2007 | 17351430 |
| efficient and stable display of functional proteins on bacterial magnetic particles using mms13 as a novel anchor molecule. | magnetic particles are increasingly used for various biomedical applications because they are easy to handle and separate from biological samples. in this work, a novel anchor molecule was used for targeted protein display onto magnetic nanoparticles. the magnetic bacterium magnetospirillum magneticum amb-1 synthesizes intracellular bacterial magnetic particles (bmps) covered with a lipid bilayer membrane. in our recent research, an integral bmp membrane protein, mms13, was isolated and used as ... | 2006 | 16391079 |
| dynamic analysis of a genomic island in magnetospirillum sp. strain amb-1 reveals how magnetosome synthesis developed. | the entire structure of a 98 kb genomic region that abounds in genes related to magnetosome synthesis was first described in the magnetospirillum sp. strain amb-1. the deletion of this 98 kb genomic region and the circular form after excision from the chromosome was detected by pcr amplification. this strongly suggests that the region has undergone a lateral gene transfer. the region has the characteristics of a genomic island: low gc content, location between two repetitive sequences, and the p ... | 2006 | 16423350 |
| comparative genome analysis of four magnetotactic bacteria reveals a complex set of group-specific genes implicated in magnetosome biomineralization and function. | magnetotactic bacteria (mtb) are a heterogeneous group of aquatic prokaryotes with a unique intracellular organelle, the magnetosome, which orients the cell along magnetic field lines. magnetotaxis is a complex phenotype, which depends on the coordinate synthesis of magnetosomes and the ability to swim and orient along the direction caused by the interaction with the earth's magnetic field. although a number of putative magnetotaxis genes were recently identified within a conserved genomic magne ... | 2007 | 17449609 |
| global gene expression analysis of iron-inducible genes in magnetospirillum magneticum amb-1. | iron uptake systems were identified by global expression profiling of magnetospirillum magneticum amb-1. feo, tpd, and ftr, which encode ferrous iron transporters, were up-regulated under iron-rich conditions. the concomitant rapid iron uptake and magnetite formation suggest that these uptake systems serve as iron supply lines for magnetosome synthesis. | 2006 | 16513757 |
| capture and release of dna using aminosilane-modified bacterial magnetic particles for automated detection system of single nucleotide polymorphisms. | bacterial magnetic particles (bmps) were modified with 3-[2-(2-aminoethylamino)-ethylamino]-propyltrimethoxysilane (aeea) to produce a dense amine surface. modification of bmps in a toluene solution resulted in an increased amine yield, and approximately 11.3 x 10(4) surface amines were detected on a single particle. the modified bmps were capable of efficient electrostatic capture of dna. the maximum amount of dna captured on 10 microg of aminosilane-modified bmps was 600 ng. a 10 mm phosphate ... | 2006 | 16523525 |
| patch clamp and phenotypic analyses of a prokaryotic cyclic nucleotide-gated k+ channel using escherichia coli as a host. | prokaryotic ion channels have been valuable in providing structural models for understanding ion filtration and channel-gating mechanisms. however, their functional examinations have remained rare and usually been carried out by incorporating purified channel protein into artificial lipid membranes. here we demonstrate the utilization of escherichia coli to host the functional analyses by examining a putative cyclic nucleotide-gated k+ channel cloned from magnetospirillum magnetotacticum, mmak. ... | 2007 | 17588940 |