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structural purity of magnetite nanoparticles in magnetotactic bacteria.magnetosome biomineralization and chain formation in magnetotactic bacteria are two processes that are highly controlled at the cellular level in order to form cellular magnetic dipoles. however, even if the magnetosome chains are well characterized, controversial results about the microstructure of magnetosomes were obtained and its possible influence in the formation of the magnetic dipole is to be specified. for the first time, the microstructure of intracellular magnetosomes was investigated ...201121247944
emcd real space maps of magnetospirillum magnetotacticum.in this study we combine energy loss magnetic circular dichroism (emcd) and energy filtered transmission electron microscopy (eftem) to map magnetic properties of nanoparticles. we show that it is a functional tool for investigating the magnetic behaviour of bio-mineralized magnetite crystals of magnetospirillum magnetotacticum. we find that the spatial resolution of our experimental set-up is in the range of less than 2 nm. the results are compared with emcd studies of abiogenic magnetite.201121316249
a novel rapid and continuous procedure for large-scale purification of magnetosomes from magnetospirillum gryphiswaldense.a new rapid and continuous procedure was developed for purifying magnetosomes from magnetospirillum gryphiswaldense msr-1 cells on a large scale. the procedure included these steps: disruption of cells with a high-pressure homogeniser, isolation of magnetosomes with a continuous magnetism isolation system accompanied by low-power ultrasonication and urea treatment, removal of adsorbed and surface proteins with proteinase k, removal of nucleic acids with electro-elution, and replacement of the pb ...201121360144
control generating of bacterial magnetic nanoparticle-doxorubicin conjugates by poly-l-glutamic acid surface modification.by using poly-l-glutamic acid (plga) to modify the membrane surface of bacterial magnetic nanoparticles (bmps), (bmp)-doxorubicin conjugates (dbmp-p) could be control generated. the doxorubicin loading ratio could be raised up to 81.7% (w/w) in comparison with that of dual functional linkers. dbmp-p was characterized by transmission electron micrographs, attenuated total reflection infrared spectroscopy, magnetic properties, and dynamic light scattering. it is found that increase of the doxorubi ...201121411921
the htra/degp family protease mame is a bifunctional protein with roles in magnetosome protein localization and magnetite biomineralization.magnetotactic bacteria contain nanometre-sized, membrane-bound organelles, called magnetosomes, which are tasked with the biomineralization of small crystals of the iron oxide magnetite allowing the organism to use geomagnetic field lines for navigation. a key player in this process is the htra/degp family protease mame. in its absence, magnetospirillum magneticum str amb-1 is able to form magnetosome membranes but not magnetite crystals, a defect previously linked to the mislocalization of magn ...201121414040
interruption of the denitrification pathway influences cell growth and magnetosome formation in magnetospirillum magneticum amb-1.aims:  intracellular magnetosome synthesis in magnetotactic bacteria has been proposed to be a process involving functions of a variety of proteins. to learn more about the genetic control that is involved in magnetosome formation, nonmagnetic mutants are screened and characterized. methods and results:  conjugation-mediated transposon mutagenesis was applied to screen for nonmagnetic mutants of magnetospirillum magneticum amb-1 that were unable to respond to the magnetic field. a mutant strain ...201121517919
magnetospirillum magneticum amb-1 peroxiredoxins contribute to the aerotolerance and genetic stability of the genomic magnetosome island.the magnetotactic bacterium magnetospirillum magneticum amb-1 can grow at variable oxygen concentrations, although the intracellular magnetic structures, magnetosomes, are only synthesized under microaerobic or anaerobic conditions. three members of the peroxiredoxin family were identified in m. magneticum amb-1. all purified recombinant proteins displayed thiol-dependent peroxidase activities. allelic replacement mutagenesis revealed that, although the absence of the three peroxidase genes had ...201121535101
self-recognition mechanism of mama, a magnetosome-associated tpr-containing protein, promotes complex assembly.the magnetosome, a biomineralizing organelle within magnetotactic bacteria, allows their navigation along geomagnetic fields. magnetosomes are membrane-bound compartments containing magnetic nanoparticles and organized into a chain within the cell, the assembly and biomineralization of magnetosomes are controlled by magnetosome-associated proteins. here, we describe the crystal structures of the magnetosome-associated protein, mama, from magnetospirillum magneticum amb-1 and magnetospirillum gry ...201121784982
magnetosome expression of functional camelid antibody fragments (nanobodies) in magnetospirillum gryphiswaldense.numerous applications of conventional and biogenic magnetic nanoparticles, such as in diagnostics, immunomagnetic separations and magnetic cell labeling, require the immobilization of antibodies. this is usually accomplished by chemical conjugation, which however, has several disadvantages, such as poor efficiency and the need for coupling chemistry. here, we describe a novel strategy to display a functional camelid antibody fragment (nanobody) from an alpaca (lama pacos) on the surface of bacte ...201121764974
single-step production of a recyclable nanobiocatalyst for organophosphate pesticides biodegradation using functionalized bacterial magnetosomes.enzymes are versatile catalysts in laboratories and on an industrial scale; improving their immobilization would be beneficial to broadening their applicability and ensuring their (re)use. lipid-coated nano-magnets produced by magnetotactic bacteria are suitable for a universally applicable single-step method of enzyme immobilization. by genetically functionalizing the membrane surrounding these magnetite particles with a phosphohydrolase, we engineered an easy-to-purify, robust and recyclable b ...201121738665
frequent mutations within the genomic magnetosome island of magnetospirillum gryphiswaldense are mediated by reca.genes for magnetosome formation in magnetotactic bacteria are clustered in large genomic magnetosome islands (mai). spontaneous deletions and rearrangements were frequently observed within these regions upon metabolic stress. this instability was speculated to be due to reca-dependent homologous recombination between the numerous sequence repeats present within the mai. here, we show that a reca deficient strain of magnetospirillum gryphiswaldense (strain ik-1) no longer exhibits genetic instabi ...201121821768
semicontinuous culture of magnetospirillum gryphiswaldense msr-1 cells in an autofermentor by nutrient-balanced and isosmotic feeding strategies.an improved strategy was developed for the high-density culture of magnetospirillum gryphiswaldense strain msr-1 and large-scale magnetosome production in both 7.5- and 42-liter autofermentors. by using a nutrient-balanced feeding strategy and the replacement of carbon and nitrogen sources to reduce accumulation of na(+) and cl(-) ions, we reduced the factors that tend to inhibit cell growth, particularly the increase of osmotic potential. semicontinuous culture was thereby achieved in the autof ...201121724877
snapping magnetosome chains by asymmetric cell division in magnetotactic bacteria.the mechanism by which prokaryotic cells organize and segregate their intracellular organelles during cell division has recently been the subject of substantial interest. unlike other microorganisms, magnetotactic bacteria (mtb) form internal magnets (known as magnetosome chain) for magnetic orientation, and thus face an additional challenge of dividing and equipartitioning this magnetic receptor to their daughter cells. although mtb have been investigated more than four decades, it is only rece ...201122066928
MamK, a bacterial actin, forms dynamic filaments in vivo that are regulated by the acidic proteins MamJ and LimJ.Bacterial actins, in contrast to their eukaryotic counterparts, are highly divergent proteins whose wide-ranging functions are thought to correlate with their evolutionary diversity. One clade, represented by the MamK protein of magnetotactic bacteria, is required for the subcellular organization of magnetosomes, membrane-bound organelles that aid in navigation along the earth's magnetic field. Using a fluorescence recovery after photobleaching assay in Magnetospirillum magneticum AMB-1, we find ...201121883528
Magnetosome chains are recruited to cellular division sites and split by asymmetric septation.Magnetotactic bacteria navigate along magnetic field lines using well-ordered chains of membrane-enclosed magnetic crystals, referred to as magnetosomes, which have emerged as model to investigate organelle biogenesis in prokaryotic systems. To become divided and segregated faithfully during cytokinesis, the magnetosome chain has to be properly positioned, cleaved and separated against intrachain magnetostatic forces. Here we demonstrate that magnetotactic bacteria use dedicated mechanisms to co ...201122026731
anaerobic degradation of 4-methylbenzoate by a new denitrifying bacterium, strain pmbn1.a novel alphabacterium isolated from freshwater sediments, strain pmbn1, degrading 4-methylbenzoate to co(2) under nitrate-reducing conditions. while strain pmbn1 utilizes several benzoate-derivatives and other polar aromatic compounds, it cannot degrade p-xylene or other hydrocarbons. based on 16s rrna gene sequence analysis, strain pmbn1 affiliates with magnetospirillum.201122179254
magnetospira thiophila, gen. nov. sp. nov., a new marine magnetotactic bacterium that represents a novel lineage within the rhodospirillaceae (alphaproteobacteria).a marine, magnetotactic bacterium, designated strain mms-1, was isolated from mud and water from a salt marsh in woods hole, massachusetts, after enrichment in defined oxygen concentration/redox gradient medium. mms-1 is an obligate microaerophile capable of chemoorganoheterotrophic and chemolithoautotrophic growth. optimal growth occurred at ph 7.0 and between 24-26 °c. chemolithoautotrophic growth occurs with thiosulfate as the electron donor and autotrophic carbon fixation is via the calvi ...201122140150
The MagA protein of magnetospirilla is not involved in bacterial magnetite biomineralization.Magnetotactic bacteria have the ability to orient along geomagnetic field lines based on the formation of magnetosomes, which are intracellular nanometer-sized, membrane-enclosed magnetic iron minerals. The formation of these unique bacterial organelles involves several processes like cytoplasmic membrane invagination and magnetosome vesicle formation, accumulation of iron in the vesicles, and crystallization of magnetite. Previous studies suggested that the magA gene may encode a magnetosome-di ...201122194451
structure and molecular evolution of cdgsh iron-sulfur domains.the recently discovered cdgsh iron-sulfur domains (cisds) are classified into seven major types with a wide distribution throughout the three domains of life. the type 1 protein mitoneet has been shown to fold into a dimer with the signature cdgsh motif binding to a [2fe-2s] cluster. however, the structures of all other types of cisds were unknown. here we report the crystal structures of type 3, 4, and 6 cisds determined at 1.5 å, 1.8 å and 1.15 å resolution, respectively. the type 3 and 4 cisd ...201121949752
intracellular magneto-spatial organization of magnetic organelles inside intact bacterial cells.magnetotactic bacteria naturally produce magnetosomes, i.e., biological membrane bound nanomagnets, at ambient conditions. it is important to understand simultaneously the possible size variations and the magnetic behavior of nano-magnets inside intact bacterial cells for both applicational purposes as well as to enhance the basic understanding of biomineralization leading to intracellular nano-magnet synthesis. in this work, we utilize high-resolution transmission electron microscopy and near-f ...201121870462
the chemical formula of a magnetotactic bacterium.elucidation of the chemical logic of life is one of the grand challenges in biology, and essential to the progress of the upcoming field of synthetic biology. treatment of microbial cells explicitly as a "chemical" species in controlled reaction (growth) environments has allowed fascinating discoveries of elemental formulae of a few species that have guided the modern views on compositions of a living cell. application of mass and energy balances on living cells has proved to be useful in modeli ...201122170293
[magnetospirillum aberrantis sp. nov., a new freshwater bacterium with magnetic inclusions]. 201122168012
how iron is transported into magnetosomes.magnetotactic bacteria are microaerophilic organisms found in sediments or stratified water columns at the oxic-anoxic transition zone or the anoxic regions below. they use magnetite-filled membrane vesicles, magnetosomes, to passively align with, and actively swim along, the geomagnetic field lines in a magneto-aerotactic search for the ideal concentration of molecular oxygen. such an efficient chemotaxis needs magnetosomes that contain nearly perfect magnetite crystals. these magnetosomes orig ...201121999528
The cation diffusion facilitator proteins MamB and MamM of Magnetospirillum gryphiswaldense have distinct and complex functions, and are involved in magnetite biomineralization and magnetosome membrane assembly.Magnetotactic bacteria form chains of intracellular membrane-enclosed, nanometre-sized magnetite crystals for navigation along the earth's magnetic field. The assembly of these prokaryotic organelles requires several specific polypeptides. Among the most abundant proteins associated with the magnetosome membrane of Magnetospirillum gryphiswaldense are MamB and MamM, which were implicated in magnetosomal iron transport because of their similarity to the cation diffusion facilitator family. Here w ...201122007638
identification of novel mimicry epitopes for cardiac myosin heavy chain-α that induce autoimmune myocarditis in a/j mice.myocarditis is one cause of sudden cardiac death in young adolescents, and individuals affected with myocarditis can develop dilated cardiomyopathy, a frequent reason for heart transplantation. exposure to environmental microbes has been suspected in the initiation of heart autoimmunity, but the direct causal link is lacking. we report here identification of novel mimicry epitopes that bear sequences similar to those in cardiac myosin heavy chain (myhc)-α 334-352. these epitopes represent bacill ...201121939961
Functional analysis of the magnetosome island in Magnetospirillum gryphiswaldense: the mamAB operon is sufficient for magnetite biomineralization.Bacterial magnetosomes are membrane-enveloped, nanometer-sized crystals of magnetite, which serve for magnetotactic navigation. All genes implicated in the synthesis of these organelles are located in a conserved genomic magnetosome island (MAI). We performed a comprehensive bioinformatic, proteomic and genetic analysis of the MAI in Magnetospirillum gryphiswaldense. By the construction of large deletion mutants we demonstrate that the entire region is dispensable for growth, and the majority of ...201122043287
magnetosomes on surface: an imaging study approach.in this study, we deposited isolated magnetosomes from magnetotactic bacteria magnetospirillum strain amb-1 onto solid surfaces using spin coating (sc) and drop coating (dc) techniques. four imaging techniques have been used to visualize the sample structure: scanning and transmission electron microscopy (sem, tem), atomic and magnetic force microscopy (afm, mfm). additionally, dynamic light scattering was applied to measure the hydrodynamic radius of agglomerated/aggregated magnetosomes in a li ...201121953296
control of the morphology and size of magnetite particles with peptides mimicking the mms6 protein from magnetotactic bacteria.mms6 is a dominant protein that tightly associates with the surface of bacterial magnetites in magnetospirillum magneticum amb-1. the protein has previously been shown to mediate the formation of uniform magnetite crystals of cubo-octahedral morphology consisting of (1 1 1) and (1 0 0) crystal faces with a narrow size distribution during chemical magnetite synthesis. in order to understand the role of this protein in chemical magnetite synthesis, magnetite formation was investigated using synthe ...201020006848
deletion of the ftsz-like gene results in the production of superparamagnetic magnetite magnetosomes in magnetospirillum gryphiswaldense.magnetotactic bacteria (mtb) synthesize unique organelles termed "magnetosomes," which are membrane-enclosed structures containing crystals of magnetite or greigite. magnetosomes form a chain around mamk cytoskeletal filaments and provide the basis for the ability of mtb to navigate along geomagnetic field lines in order to find optimal microaerobic habitats. genomes of species of the mtb genus magnetospirillum, in addition to a gene encoding the tubulin-like ftsz protein (involved in cell divis ...201020023033
inducible expression of transmembrane proteins on bacterial magnetic particles in magnetospirillum magneticum amb-1.bacterial magnetic particles (bacmps) produced by the magnetotactic bacterium magnetospirillum magneticum amb-1 are used for a variety of biomedical applications. in particular, the lipid bilayer surrounding bacmps has been reported to be amenable to the insertion of recombinant transmembrane proteins; however, the display of transmembrane proteins in bacmp membranes remains a technical challenge due to the cytotoxic effects of the proteins when they are overexpressed in bacterial cells. in this ...201020038711
preparation of genomic dna from a single species of uncultured magnetotactic bacterium by multiple-displacement amplification.magnetotactic bacteria comprise a phylogenetically diverse group that is capable of synthesizing intracellular magnetic particles. although various morphotypes of magnetotactic bacteria have been observed in the environment, bacterial strains available in pure culture are currently limited to a few genera due to difficulties in their enrichment and cultivation. in order to obtain genetic information from uncultured magnetotactic bacteria, a genome preparation method that involves magnetic separa ...201020081000
reduced inorganic sulfur oxidation supports autotrophic and mixotrophic growth of magnetospirillum strain j10 and magnetospirillum gryphiswaldense.magnetotactic bacteria are present at the oxic-anoxic transition zone where opposing gradients of oxygen and reduced sulfur and iron exist. growth of non-magnetotactic lithoautotrophic magnetospirillum strain j10 and its close relative magnetotactic magnetospirillum gryphiswaldense was characterized in microaerobic continuous culture. both strains were able to grow in mixotrophic (acetate + sulfide) and autotrophic (sulfide or thiosulfate) conditions. autotrophically growing cells completely con ...201020105221
a second actin-like mamk protein in magnetospirillum magneticum amb-1 encoded outside the genomic magnetosome island.magnetotactic bacteria are able to swim navigating along geomagnetic field lines. they synthesize ferromagnetic nanocrystals that are embedded in cytoplasmic membrane invaginations forming magnetosomes. regularly aligned in the cytoplasm along cytoskeleton filaments, the magnetosome chain effectively forms a compass needle bestowing on bacteria their magnetotactic behaviour. a large genomic island, conserved among magnetotactic bacteria, contains the genes potentially involved in magnetosome for ...201020161777
cre-lox-based method for generation of large deletions within the genomic magnetosome island of magnetospirillum gryphiswaldense.magnetosome biomineralization and magnetotaxis in magnetotactic bacteria are controlled by numerous, mostly unknown gene functions that are predominantly encoded by several operons located within the genomic magnetosome island (mai). genetic analysis of magnetotactic bacteria has remained difficult and requires the development of novel tools. we established a cre-lox-based deletion method which allows the excision of large genomic fragments in magnetospirillum gryphiswaldense. two conjugative su ...201020173068
isolation and characterization of a marine magnetotactic spirillum axenic culture qh-2 from an intertidal zone of the china sea.magnetotactic bacteria (mtb) are ubiquitous in aquatic habitats. because of their fastidious requirements for growth conditions, only very few axenic mtb cultures have been obtained worldwide. in this study, we report a novel marine magnetotactic spirillum axenic culture, designated as qh-2, isolated from the china sea. it was able to grow in semi-solid or liquid chemically defined medium. the cells were amphitrichously flagellated and contained one single magnetosome chain with an average numbe ...201020178843
comprehensive genetic dissection of the magnetosome gene island reveals the step-wise assembly of a prokaryotic organelle.although membrane-bounded compartments are commonly considered a unique eukaryotic characteristic, many species of bacteria have organelles. compartmentalization is well studied in eukaryotes; however, the molecular factors and processes leading to organelle formation in bacteria are poorly understood. we use the magnetosome compartments of magnetotactic bacteria as a model system to investigate organelle biogenesis in a prokaryotic system. the magnetosome is an invagination of the cell membrane ...201020212111
purification of the m. magneticum strain amb-1 magnetosome associated protein mamadelta41.magnetotactic bacteria comprise a diverse group of aquatic microorganisms that are able to orientate themselves along geomagnetic fields. this behavior is believed to aid their search for suitable environments (1). this capability is conferred by the magnetosome, a subcellular organelle that consists of a linear-chain assembly of lipid vesicles each able to biomineralize and enclose a ~50-nm crystal of magnetite or greigite. a principle component of the magnetosome that was shown to be required ...201020339346
identification and functional characterization of liposome tubulation protein from magnetotactic bacteria.magnetotactic bacteria synthesize intracellular magnetosomes that are comprised of membrane-enveloped magnetic crystals. in this study, to identify the early stages of magnetosome formation, we isolated magnetosomes containing small magnetite crystals and those containing regular-sized magnetite crystals from magnetospirillum magneticum amb-1. this was achieved by using a novel size fractionation technique, resulting in the identification of a characteristic protein (amb1018/mamy) from the small ...201020345667
surface modification of magnetic nanoparticles using asparagines-serine polypeptide designed to control interactions with cell surfaces.surface modification is an important part of the fabrication of nanoparticles that have specific properties and functions. here we describe the development of a functional polypeptide and a simple available technology for surface modification of nanoparticles. a ns polypeptide, which is 100 amino acids composed of repeated units of four asparagine and one serine residue (ns), as a molecule for nanoparticle surface modification was designed. modification of the surface of a magnetic nanoparticle ...201020363023
[geographical distribution of magnetotactic bacteria].magnetotactic bacteria (mtb) are widely distributed in aquatic environments. to assess the correlation between their evolutionary relatedness and geographic distribution, we analyzed 239 16s rdna sequences available in the genbank, and constructed phylogenetic trees based on the sequences. after elimination of redundant sequences by grouping those with identity > 97% into a single one, we analyzed in detail total 139 16s rdna sequences, including 55 from marine mtb and 82 from freshwater sequenc ...201020391717
visualization and structural analysis of the bacterial magnetic organelle magnetosome using atomic force microscopy.the unique ability of magnetotactic bacteria to navigate along a geomagnetic field is accomplished with the help of prokaryotic organelles, magnetosomes. the magnetosomes have well-ordered chain-like structures, comprising membrane-enveloped, nano-sized magnetic crystals, and various types of specifically associated proteins. in this study, we applied atomic force microscopy (afm) to investigate the spatial configuration of isolated magnetosomes from magnetospirillum magneticum amb-1 in near-nat ...201020439702
an mcp-like protein interacts with the mamk cytoskeleton and is involved in magnetotaxis in magnetospirillum magneticum amb-1.magnetotactic bacteria have the unique capacity of aligning and swimming along geomagnetic field lines, a behavior called magnetotaxis. although this behavior has been observed for 40 years, little is known about its mechanism. magnetotactic bacteria synthesize unique organelles, magnetosomes, which are magnetic crystals enveloped by membrane. they form chains with the help of the filamentous cytoskeletal protein mamk and impart a net magnetic-dipole moment to the bacterium. the current model pr ...201020471399
cell division in magnetotactic bacteria splits magnetosome chain in half.cell division in magnetotactic bacteria has attracted much interest, speculation and hypothesis with respect to the biomineralised chains of magnetic iron-oxide particles known as magnetosomes. here we report direct transmission electron microscopy (tem) evidence that division occurs at a central point of the cell and the chain, cleaving the magnetosome chain in two. additionally, the new magnetosome chain relocates rapidly to the centre of the daughter cell and the number of magnetosomes is dir ...201020473965
loss of the actin-like protein mamk has pleiotropic effects on magnetosome formation and chain assembly in magnetospirillum gryphiswaldense.magnetotactic bacteria synthesize magnetosomes, which are unique organelles consisting of membrane-enclosed magnetite crystals. for magnetic orientation individual magnetosome particles are assembled into well-organized chains. the actin-like mamk and the acidic mamj proteins were previously implicated in chain assembly. while mamk was suggested to form magnetosome-associated cytoskeletal filaments, mamj is assumed to attach the magnetosome vesicles to these structures. although the deletion of ...201020487281
magnetospirillum bellicus sp. nov., a novel dissimilatory perchlorate-reducing alphaproteobacterium isolated from a bioelectrical reactor.previously isolated dissimilatory perchlorate-reducing bacteria (dprb) have been primarily affiliated with the betaproteobacteria. enrichments from the cathodic chamber of a bioelectrical reactor (ber) inoculated from creek water in berkeley, ca, yielded a novel organism most closely related to a previously described strain, wd (99% 16s rrna gene identity). strain vdy(t) has 96% 16s rrna gene identity to both magnetospirillum gryphiswaldense and magnetospirillum magnetotacticum, and along with s ...201020495050
deletion of a fur-like gene affects iron homeostasis and magnetosome formation in magnetospirillum gryphiswaldense.magnetotactic bacteria synthesize specific organelles, the magnetosomes, which are membrane-enveloped crystals of the magnetic mineral magnetite (fe(3)o(4)). the biomineralization of magnetite involves the uptake and intracellular accumulation of large amounts of iron. however, it is not clear how iron uptake and biomineralization are regulated and balanced with the biochemical iron requirement and intracellular homeostasis. in this study, we identified and analyzed a homologue of the ferric upt ...201020562310
domain reorientation and rotation of an intracellular assembly regulate conduction in kir potassium channels.potassium channels embedded in cell membranes employ gates to regulate k+ current. while a specific constriction in the permeation pathway has historically been implicated in gating, recent reports suggest that the signature ion selectivity filter located in the outer membrane leaflet may be equally important. inwardly rectifying k+ channels also control the directionality of flow, using intracellular polyamines to stem ion efflux by a valve-like action. this study presents crystallographic evid ...201020564790
simultaneously discrete biomineralization of magnetite and tellurium nanocrystals in magnetotactic bacteria.magnetotactic bacteria synthesize intracellular magnetosomes comprising membrane-enveloped magnetite crystals within the cell which can be manipulated by a magnetic field. here, we report the first example of tellurium uptake and crystallization within a magnetotactic bacterial strain, magnetospirillum magneticum amb-1. these bacteria independently crystallize tellurium and magnetite within the cell. this is also highly significant as tellurite (teo(3)(2-)), an oxyanion of tellurium, is harmful ...201020581185
crystallization and preliminary crystallographic analysis of the magnetospirillum magneticum amb-1 and m. gryphiswaldense msr-1 magnetosome-associated proteins mama.mama is a unique magnetosome-associated protein that is predicted to contain six sequential tetratricopeptide-repeat (tpr) motifs. the tpr structural motif serves as a template for protein-protein interactions and mediates the assembly of multi-protein complexes. here, the crystallization and preliminary x-ray analysis of recombinant and purified magnetospirillum magneticum and m. gryphiswaldense mama are reported for the first time. m. gryphiswaldense mamadelta41 crystallized in the tetragonal ...201020606283
in vivo biotinylation of bacterial magnetic particles by a truncated form of escherichia coli biotin ligase and biotin acceptor peptide.escherichia coli biotin ligase can attach biotin molecules to a lysine residue of biotin acceptor peptide (bap), and biotinylation of particular bap-fused proteins in cells was carried out by coexpression of e. coli biotin ligase (in vivo biotinylation). this in vivo biotinylation technology has been applied for protein purification, analysis of protein localization, and protein-protein interaction in eukaryotic cells, while such studies have not been reported in bacterial cells. in this study, ...201020622127
mamo and mame genes are essential for magnetosome crystal biomineralization in magnetospirillum gryphiswaldense msr-1.four non-magnetic mutants of magnetospirillum gryphiswaldense strain msr-1 were isolated by transposon mutagenesis and found to contain interruption of either the mamo or mame gene within the mamab operon. studies indicated that mamo and mame genes are essential for magnetosome crystal biomineralization in msr-1. this is the first report of a single gene (mamo or mame) whose mutation affects crystal biomineralization in msr-1.201020674739
[influence of native bacterial magnetic particles on mouse immune response].to study the influence of native bacterial magnetic particles on mouse immune response.201020687349
development of cellular magnetic dipoles in magnetotactic bacteria.magnetotactic bacteria benefit from their ability to form cellular magnetic dipoles by assembling stable single-domain ferromagnetic particles in chains as a means to navigate along earth's magnetic field lines on their way to favorable habitats. we studied the assembly of nanosized membrane-encapsulated magnetite particles (magnetosomes) by ferromagnetic resonance spectroscopy using magnetospirillum gryphiswaldense cultured in a time-resolved experimental setting. the spectroscopic data show th ...201020713012
detection of endogenous magnetic nanoparticles with a tunnelling magneto resistance sensor.the magnetotactic bacterium magnetospirillum sp. has been cultured and the properties of its endogenous magnetic nanoparticles characterized. electron-microscopic analyses indicate that the endogenous magnetite nanoparticles in magnetospirillum sp. are coated with a 3-4 nm thick transparent shell, forming a magnetosome. these magnetite nanoparticles had diameters of 50.9+/-13.3 nm, in good agreement with the diameter of 40.6+/-1.2 nm extracted from magnetometry. each magnetospirillum sp. bacteri ...201020732892
cell biology of prokaryotic organelles.mounting evidence in recent years has challenged the dogma that prokaryotes are simple and undefined cells devoid of an organized subcellular architecture. in fact, proteins once thought to be the purely eukaryotic inventions, including relatives of actin and tubulin control prokaryotic cell shape, dna segregation, and cytokinesis. similarly, compartmentalization, commonly noted as a distinguishing feature of eukaryotic cells, is also prevalent in the prokaryotic world in the form of protein-bou ...201020739411
enhancement of magnetotactic bacterial yield in a modified msgm medium without alteration of magnetosomes properties.magnetotactic bacteria (mtb), magnetospirillum magnetotacticum (ms-1) were successfully grown in modified magnetic spirillum growth medium (msgm) at normal laboratory environment. about five-time increase in the bacterial yield was achieved in the modified msgm medium without compromising their magnetosomes properties. transmission electron and scanning electron microscopy (tem & sem) were used for morphological study of mtb. energy dispersive analysis of x-rays (edax) and vibrating sample magne ...201020795371
rapid separation and immunoassay for low levels of salmonella in foods using magnetosome-antibody complex and real-time fluorescence quantitative pcr.a rapid and economical method for detecting salmonella was developed, based on a novel complex for immunomagnetic separation, which was composed of anti-salmonella polyclonal antibody (ab) and magnetosome (bacterial magnetic particle, bmp) produced by the bacterium magnetospirillum gryphiswaldense msr-1. bmp-ab complex was used to capture salmonella from pure suspensions of s. dublin, s. enteritidis, s. aesch, s. agona, s. abony and s. bareily, from mixed suspensions of s. dublin and vibrio para ...201020886524
isolation and characterization of reyranella massiliensis gen. nov., sp. nov. from freshwater samples with an amoeba co-culture procedure.the analysis of three water samples from two cooling towers and one river allowed us to isolate three strains of a novel alphaproteobacterium species, which is phylogenetically related to uncultured alphaproteobacteria. based upon 16s rrna gene sequence analysis and phenotypic characterization, we propose to name this new species reyranella massiliensis gen. nov, sp. nov., type strain 521t (=csur p115, =dsm 23428). the closest cultivable microorganism to this new bacterium is a member of the gen ...201020889765
synthesis of cellular organelles containing nano-magnets stunts growth of magnetotactic bacteria.magnetotactic bacteria are unique prokaryotes possessing the feature of cellular organelles called magnetosomes (membrane bound 40-50 nm vesicles entrapping a magnetic nano-crystal of magnetite or greigite). the obvious energetic impact of sophisticated eukaryotic-like membrane-bound organelle assembly on a presumably simpler prokaryotic system is not addressed in literature. in this work, while presenting evidence of direct coupling of carbon source consumption to synthesis of magnetosomes, we ...201021128392
phototaxis in the magnetotactic bacterium magnetospirillum magneticum strain amb-1 is independent of magnetic fields.magnetotactic bacteria (mtb) can rapidly relocate to optimal habitats by magneto-aerotaxis. little is known about mtb phototaxis, a response that might also aid navigation. in this study, we analyzed the relationship between phototaxis and magnetotaxis in magnetospirillum magneticum strain amb-1. magnotactic amb-1 cells migrated toward light, and migration increased with higher light intensity. this response was independent of wavelength, as amb-1 cells migrated equally toward light from 400 to ...201021136050
efficient conjugation doxorubicin to bacterial magnetic nanoparticles via a triplex hands coupling reagent.by using a novel triplex "hand" coupling reagent, tris-succinimidyl aminotriacetate (tsat), doxorubicin loading efficiency of bmp can be greatly enhanced in comparison with that of dual functional linkers. the drug loading ratio of doxorubicin-coupled bacterial magnetic nanoparticles produced by this method (dbmp-t) is 62%. dbmp-t disperse well, have a narrow size distribution, exhibit a high magnetic response, is sensitive to ph to facilitate drug release and are strongly cytotoxic to hepg2 and ...201021137755
large-scale production of magnetosomes by chemostat culture of magnetospirillum gryphiswaldense at high cell density.magnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of fe3o4, termed magnetosomes. current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. however, t ...201021144001
magnetically actuated propulsion at low reynolds numbers: towards nanoscale control.significant progress has been made in the fabrication of micron and sub-micron structures whose motion can be controlled in liquids under ambient conditions. the aim of many of these engineering endeavors is to be able to build and propel an artificial micro-structure that rivals the versatility of biological swimmers of similar size, e.g. motile bacterial cells. applications for such artificial "micro-bots" are envisioned to range from microrheology to targeted drug delivery and microsurgery, a ...201021152575
mms6 protein regulates crystal morphology during nano-sized magnetite biomineralization in vivo.biomineralization, the process by which minerals are deposited by organisms, has attracted considerable attention because this mechanism has shown great potential to inspire bottom-up material syntheses. to understand the mechanism for morphological regulation that occurs during biomineralization, many regulatory proteins have been isolated from various biominerals. however, the molecular mechanisms that regulate the morphology of biominerals remain unclear because there is a lack of in vivo evi ...201021169637
bioengineering of bacterial magnetic particles and their applications in biotechnology.magnetic particles have attracted much attention for their versatile uses in biotechnology, especially in medical applications. the major advantage of magnetic particles is that they can be easily manipulated by magnetic forces. magnetotactic bacteria synthesize nano-sized biomagnetites, otherwise known as bacterial magnetic particles (bacmps) that are individually enveloped by a lipid bilayer membrane. the mechanisms of bacmp synthesis have been analyzed by genomic, proteomic, and bioinformatic ...201021171958
effects of pulsed magnetic field on the formation of magnetosomes in the magnetospirillum sp. strain amb-1.magnetotactic bacteria are a diverse group of microorganisms which possess one or more chains of magnetosomes and are endowed with the ability to use geomagnetic fields for direction sensing, thus providing a simple and excellent model for the study of magnetite-based magnetoreception. in this study, a 50 hz, 2 mt pulsed magnetic field (pmf) was applied to study the effects on the formation of magnetosomes in magnetospirillum sp. strain amb-1. the results showed that the cellular magnetism (r(ma ...201019780093
in vivo display of a multisubunit enzyme complex on biogenic magnetic nanoparticles.magnetosomes are unique bacterial organelles comprising membrane-enveloped magnetic crystals produced by magnetotactic bacteria. because of several desirable chemical and physical properties, magnetosomes would be ideal scaffolds on which to display highly complicated biological complexes artificially. as a model experiment for the functional expression of a multisubunit complex on magnetosomes, we examined the display of a chimeric bacterial rnase p enzyme composed of the protein subunit (c5) o ...200919837839
anaerobic metabolism of phenol in proteobacteria and further studies of phenylphosphate carboxylase.anaerobic phenol metabolism was studied in three facultative aerobic denitrifying bacteria, thauera aromatica, "aromatoleum aromaticum" strain ebn1 (betaproteobacteria), and magnetospirillum sp. (alphaproteobacterium). all species formed phenylphosphate and contained phenylphosphate carboxylase but not phenol carboxylase activity. this is in contrast to direct phenol carboxylation by fermenting bacteria. antisera raised against subunits of the thauera phenylphosphate synthase and phenylphosphate ...200919838679
[protein display onto nano-sized bacterial magnetic particles for receptor analysis].magnetic particles offer vast potential in ushering new techniques, especially in biomedical applications, as they can be easily manipulated by magnetic force. magnetotactic bacteria synthesize nano-sized biomagnetites, otherwise known as bacterial magnetic particles (bacmps) that are individually enveloped by a lipid bilayer membrane. bacmps are ultrafine magnetite crystals (50-100 nm diameters) with uniform morphology produced by magnetospirillum magneticum amb-1. based on our elucidations on ...200919881203
magnetic separation of melanoma-specific cytotoxic t lymphocytes from a vaccinated melanoma patient's blood using mhc/peptide complex-conjugated bacterial magnetic particles.target antigen-specific cytotoxic t lymphocytes (ctls) play a key role in anticancer and antivirus immunity in the body, and purification of ctls from heterogeneous immune cells is desired for an efficient cancer immunotherapy and fundamental research. herein, a novel magnetic nanoparticle conjugated with major histocompatibility complex (mhc)/peptide complexes was developed for the magnetic separation of melanoma-specific ctls. to conjugate biotinylated mhc/peptide complexes on nanosized bacter ...200919143499
effects of static magnetic field on magnetosome formation and expression of mama, mms13, mms6 and maga in magnetospirillum magneticum amb-1.magnetotactic bacteria produce nanometer-size intracellular magnetic crystals. the superior crystalline and magnetic properties of magnetosomes have been attracting much interest in medical applications. to investigate effects of intense static magnetic field on magnetosome formation in magnetospirillum magneticum amb-1, cultures inoculated with either magnetic or non-magnetic pre-cultures were incubated under 0.2 t static magnetic field or geomagnetic field. the results showed that static magne ...200919165820
nano-sized bacterial magnetic particles displaying pyruvate phosphate dikinase for pyrosequencing.there is a high demand for inexpensive and high-throughput dna sequencing technologies in molecular biology and applied biosciences. in this study, novel nano-sized magnetic particles displaying enzymes for pyrosequencing, a rather novel bioluminometric dna sequencing method based on the sequencing-by-synthesis principle by employing a cascade of several enzymatic reactions, was developed. a highly thermostable enzyme, pyruvate phosphate dikinase (ppdk) which converts ppi to atp was successfully ...200919170242
manganese in biogenic magnetite crystals from magnetotactic bacteria.magnetotactic bacteria produce either magnetite (fe(3)o(4)) or greigite (fe(3)s(4)) crystals in cytoplasmic organelles called magnetosomes. whereas greigite magnetosomes can contain up to 10 atom% copper, magnetite produced by magnetotactic bacteria was considered chemically pure for a long time and this characteristic was used to distinguish between biogenic and abiogenic crystals. recently, it was shown that magnetosomes containing cobalt could be produced by three strains of magnetospirillum. ...200919187208
direct magnetic separation of immune cells from whole blood using bacterial magnetic particles displaying protein g.direct separation of target cells from mixed population, such as peripheral blood, umbilical cord blood, and bone marrow, is an essential technique for various therapeutic or diagnosis applications. in this study, novel particles were fabricated, and direct magnetic separation of immune cells from whole blood using such particles was performed. the magnetotactic bacterium magnetospirillum magneticum amb-1 synthesizes intracellular bacterial magnetic particles (bacmps), and protein g was expresse ...200919197981
the targeting of endothelial progenitor cells to a specific location within a microfluidic channel using magnetic nanoparticles.a common problem with the in vivo therapeutic applications of cells is that cells can rapidly disappear into the circulatory system after an injection. magnetic nanoparticles can be used to solve this problem. bacterial magnetic nanoparticles were used in this study for targeting stem cells at a specific location within a microfluidic channel. magnetic nanoparticles were isolated from magnetospirillum sp. amb-1 and delivered to endothelial progenitor cells (epcs). cellular uptake of magnetic nan ...200918836835
comparative analysis of magnetosome gene clusters in magnetotactic bacteria provides further evidence for horizontal gene transfer.the organization of magnetosome genes was analysed in all available complete or partial genomic sequences of magnetotactic bacteria (mtb), including the magnetosome island (mai) of the magnetotactic marine vibrio strain mv-1 determined in this study. the mai was found to differ in gene content and organization between magnetospirillum species and strains mv-1 or mc-1. although a similar organization of magnetosome genes was found in all mtb, distinct variations in gene order and sequence similar ...200919220405
magnetic separation of human podocalyxin-like protein 1 (hpclp1)-positive cells from peripheral blood and umbilical cord blood using anti-hpclp1 monoclonal antibody and protein a expressed on bacterial magnetic particles.hemangioblasts are common progenitors of hematopoietic and angiogenic cells, which have been demonstrated in the mouse to possess a unique cell surface marker, podocalyxin-like protein 1 (pclp1) (hara, t. et al., immunity, 11: 567-578. 1999). in this study, we prepared a novel monoclonal antibody against human pclp1 (hpclp1) and attempted to isolate human hematopoietic progenitor cells from umbilical cord blood and peripheral blood using nano-sized bacterial magnetic particles (bacmps) coupled w ...200919293534
high-sensitivity detection of fruit tree viruses using bacterial magnetic particles.prunus necrotic ring spot virus (pnrsv) and grapevine fanleaf virus (gflv) were detected by fluoroimmunoassay using bacterial magnetic particles (bmps), and a double antibody sandwich enzyme linked immunosorbent assay (das-elisa). for the fluoroimmunoassay, fluorescein isothiocyanate labeled anti-pnrsv antibody or anti-gflv antibody was conjugated onto bmps of magnetospirillum gryphiswaldense msr-1. with this method, a very low minimum antigen concentration (1 x 10(6) dilution of the original sa ...200919341408
characterization of bacterial magnetotactic behaviors by using a magnetospectrophotometry assay.magnetotactic bacteria have the unique capacity of synthesizing intracellular single-domain magnetic particles called magnetosomes. the magnetosomes are usually organized in a chain that allows the bacteria to align and swim along geomagnetic field lines, a behavior called magnetotaxis. two mechanisms of magnetotaxis have been described. axial magnetotactic cells swim in both directions along magnetic field lines. in contrast, polar magnetotactic cells swim either parallel to the geomagnetic fie ...200919376916
identification of promoters for efficient gene expression in magnetospirillum gryphiswaldense.to develop an expression system for the magnetotactic bacterium magnetospirillum gryphiswaldense, we compared gene expression from the widely used escherichia coli p(lac) promoter with that from known and predicted genuine m. gryphiswaldense promoters. with the use of green fluorescent protein as a reporter, the highest expression level was observed with the magnetosomal p(mamdc) promoter. we demonstrate that this promoter can be used for the expression of modified magnetosome proteins to genera ...200919395573
targeted distribution of bacterial magnetosomes isolated from magnetospirillum gryphiswaldense msr-1 in healthy sprague-dawley rats.bacterial magnetosomes (bms) have drawn great interest as novel magnetic targeted carriers and have been widely used as carriers for enzymes, nucleic acids and antibodies experimentally. however, bms have rarely been employed as drug carriers in vivo mainly due to the unclear biocompatibility and pharmacokinetics of bms. in this study, we provided a unique effective method for purification and sterilization of bms. the bms obtained exhibited sterility, high purity, narrowed size-distribution, un ...200919435053
contributions of phosphate to dna adsorption/desorption behaviors on aminosilane-modified magnetic nanoparticles.the adsorption and desorption behaviors of dna on aminosilane-modified magnetic nanoparticles were investigated by altering both type of anions and solvation state to achieve eficient recovery of dna useful for subsequent polymerase chain reaction (pcr) analysis. the effects of multiple anions in accordance with the hofmeister ion series were determined to clarify the contribution of phosphate ions on the effective desorption of dna from aminosilane surfaces. efficient dna desorption (85% recove ...200919437706
effect of oxidative stress on the growth of magnetic particles in magnetospirillum magneticum.individual magnetosome-containing magnetic mineral particles (mmp) from magnetotactic bacteria grow rapidly such that only a small fraction (5%) of all magnetosomes contain dwarf (< or =20 nm) mmp. studies of the developmental stages in the growth of mmp are difficult due to the absence of techniques to separate dwarf from mature particles and because the former are sensitive to extraction procedures. here, o2 stress was used to inhibit mmp expression in magnetospirillum magneticum strain amb-1. ...200919440983
magnetosome formation and expression of mama, mms13, mms6 and maga in magnetospirillum magneticum amb-1 exposed to pulsed magnetic field.to investigate the effects of pulsed magnetic field on magnetosome formation in magnetospirillum magneticum amb-1, cultures inoculated with either mangetic or non-magnetic pre-cultures were incubated under 1 mt pulsed magnetic field. magnetism of cells was measured by using spectrophotometer coupled with applied magnetic fields and the values were described as c(mag). magnetosome in cells was counted by transmission electron microscopy observation. the results showed that pulsed magnetic field d ...200919459005
assemblies of aligned magnetotactic bacteria and extracted magnetosomes: what is the main factor responsible for the magnetic anisotropy?the origin of the magnetic anisotropy is explained in an assembly of aligned magnetic nanoparticles. for that, nanoparticles synthesized biologically by magnetospirillum magneticum amb-1 magnetotactic bacteria are used. for the first time, it is possible to differentiate between the two contributions arising from the alignment of the magnetosome easy axes and the strength of the magnetosome dipolar interactions. the magnetic anisotropy is shown to arise mainly from the dipolar interactions betwe ...200919459692
on the change in bacterial size and magnetosome features for magnetospirillum magnetotacticum (ms-1) under high concentrations of zinc and nickel.the characteristic size, shape and specific alignment of magnetite crystals synthesized by magnetotactic bacteria is a highly coordinated process with precise control over magnetosome vesicle formation, uptake and transport of fe, and magnetite biomineralization. magnetosome membranes along with some specific membrane proteins regulate crystal nucleation and morphology of magnetite. several previous works have indicated that the morphology of mature magnetite crystals is largely unaffected by en ...200919500838
proteomic analysis of irregular, bullet-shaped magnetosomes in the sulphate-reducing magnetotactic bacterium desulfovibrio magneticus rs-1.recent molecular studies on magnetotactic bacteria have identified a number of proteins associated with bacterial magnetites (magnetosomes) and elucidated their importance in magnetite biomineralisation. however, these analyses were limited to magnetotactic bacterial strains belonging to the alpha-subclass of proteobacteria. we performed a proteomic analysis of magnetosome membrane proteins in desulfovibrio magneticus strain rs-1, which is phylogenetically classified as a member of the delta-pro ...200919579222
microbial sulfide oxidation in the oxic-anoxic transition zone of freshwater sediment: involvement of lithoautotrophic magnetospirillum strain j10.the oxic-anoxic transition zone (oatz) of freshwater sediments, where opposing gradients exist of reduced iron and sulfide with oxygen, creates a suitable environment for microorganisms that derive energy from the oxidation of iron or sulfide. gradient microcosms incubated with freshwater sediment showed rapid microbial turnover of sulfide and oxygen compared with sterile systems. microcosms with fes as a substrate also showed growth at the oatz and subsequent dilution series resulted in the iso ...200919659746
visualizing implanted tumors in mice with magnetic resonance imaging using magnetotactic bacteria.to determine if magnetotactic bacteria can target tumors in mice and provide positive contrast for visualization using magnetic resonance imaging.200919671860
whole genome sequence of desulfovibrio magneticus strain rs-1 revealed common gene clusters in magnetotactic bacteria.magnetotactic bacteria are ubiquitous microorganisms that synthesize intracellular magnetite particles (magnetosomes) by accumulating fe ions from aquatic environments. recent molecular studies, including comprehensive proteomic, transcriptomic, and genomic analyses, have considerably improved our hypotheses of the magnetosome-formation mechanism. however, most of these studies have been conducted using pure-cultured bacterial strains of alpha-proteobacteria. here, we report the whole-genome seq ...200919675025
magnetic resonance imaging of cells overexpressing maga, an endogenous contrast agent for live cell imaging.molecular imaging with magnetic resonance imaging (mri) may benefit from the ferrimagnetic properties of magnetosomes, membrane-enclosed iron biominerals whose formation in magnetotactic bacteria is encoded by multiple genes. one such gene is maga, a putative iron transporter. we have examined expression of maga in mouse neuroblastoma n2a cells and characterized their response to iron loading and cellular imaging by mri. maga expression augmented both prussian blue staining and the elemental iro ...200919723470
identification of iron transporters expressed in the magnetotactic bacterium magnetospirillum magnetotacticum.the magnetotactic bacterium magnetospirillum magnetotacticum ms-1 mineralizes the magnetite (fe(3)o(4)) crystal and organizes a highly ordered intracellular structure, called the magnetosome. however, the iron transport system, which supports the biogenesis of magnetite, is not fully understood. in this study, we first identified the expressions of both the ferric and the ferrous iron transporter proteins in m. magnetotacticum. the cellular protein compositions of ferric and ferrous iron-rich cu ...200918972162
preparation and anti-tumor efficiency evaluation of doxorubicin-loaded bacterial magnetosomes: magnetic nanoparticles as drug carriers isolated from magnetospirillum gryphiswaldense.bacterial magnetosomes (bms) are commonly used as vehicles for certain enzymes, nucleic acids and antibodies, although they have never been considered drug carriers. to evaluate the clinical potential of bms extracted from magnetospirillum gryphiswaldense in cancer therapy, doxorubicin (dox) was loaded onto the purified bms at a ratio of 0.87 +/- 0.08 mg/mg using glutaraldehyde. the dox-coupled bms (dbms) and bms exhibited uniform sizes and morphology evaluated by tem. the diameters of dbms and ...200818980188
[magnetotactic bacteria's organella, magnetosome-localization, and cytoskeleton]. 200819044287
sinusoidal magnetic field stimulates magnetosome formation and affects mama, mms13, mms6, and maga expression in magnetospirillum magneticum amb-1.magnetic particles are currently one of the most important materials in the industrial sector, where they have been widely used for biotechnological and biomedical applications. to investigate the effects of the imposed magnetic field on biomineralization in magnetospirillum magneticum amb-1 and to suggest a new approach that enhances formation of magnetosomes, cultures inoculated with either magnetic or nonmagnetic precultures were incubated under a sinusoidal magnetic field or geomagnetic fiel ...200819096456
the major magnetosome proteins mamgfdc are not essential for magnetite biomineralization in magnetospirillum gryphiswaldense but regulate the size of magnetosome crystals.magnetospirillum gryphiswaldense and related magnetotactic bacteria form magnetosomes, which are membrane-enclosed organelles containing crystals of magnetite (fe3o4) that cause the cells to orient in magnetic fields. the characteristic sizes, morphologies, and patterns of alignment of magnetite crystals are controlled by vesicles formed of the magnetosome membrane (mm), which contains a number of specific proteins whose precise roles in magnetosome formation have remained largely elusive. here, ...200817965152
mesaconyl-coenzyme a hydratase, a new enzyme of two central carbon metabolic pathways in bacteria.the coenzyme a (coa)-activated c5-dicarboxylic acids mesaconyl-coa and beta-methylmalyl-coa play roles in two as yet not completely resolved central carbon metabolic pathways in bacteria. first, these compounds are intermediates in the 3-hydroxypropionate cycle for autotrophic co2 fixation in chloroflexus aurantiacus, a phototrophic green nonsulfur bacterium. second, mesaconyl-coa and beta-methylmalyl-coa are intermediates in the ethylmalonyl-coa pathway for acetate assimilation in various bacte ...200818065535
in chlamydomonas, the loss of nd5 subunit prevents the assembly of whole mitochondrial complex i and leads to the formation of a low abundant 700 kda subcomplex.in the green alga chlamydomonas reinhardtii, a mutant deprived of complex i enzyme activity presents a 1t deletion in the mitochondrial nd5 gene. the loss of the nd5 subunit prevents the assembly of the 950 kda whole complex i. instead, a low abundant 700 kda subcomplex, loosely associated to the inner mitochondrial membrane, is assembled. the resolution of the subcomplex by sds-page gave rise to 19 individual spots, sixteen having been identified by mass spectrometry analysis. eleven, mainly as ...200818258177
development of a cell surface display system in a magnetotactic bacterium, "magnetospirillum magneticum" amb-1.bacterial cell surface display is a widely used technology for bioadsorption and for the development of a variety of screening systems. magnetotactic bacteria are unique species of bacteria due to the presence of magnetic nanoparticles within them. these intracellular, nanosized (50 to 100 nm) magnetic nanoparticles enable the cells to migrate and be manipulated by magnetic force. in this work, using this unique characteristic and based on whole-genomic and comprehensive proteomic analyses of th ...200818378651
high-yield growth and magnetosome formation by magnetospirillum gryphiswaldense msr-1 in an oxygen-controlled fermentor supplied solely with air.magnetotactic bacteria are difficult to grow under defined conditions in culture, which has presented a major obstacle to commercial application of magnetosomes. we studied the relationships among the cell growth, magnetosome formation, dissolved oxygen concentration (do), and the ability to supply oxygen to the cells. mass culture of magnetospirillum gryphiswaldense msr-1 for the production of magnetosomes was established in a 42-l fermentor under the following conditions: (1) sterile air was t ...200818425510
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