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characterisation of the dissimilatory reduction of fe(iii)-oxyhydroxide at the microbe-mineral interface: the application of stxm-xmcd.a combination of scanning transmission x-ray microscopy and x-ray magnetic circular dichroism was used to spatially resolve the distribution of different carbon and iron species associated with shewanella oneidensis mr-1 cells. s. oneidensis mr-1 couples the reduction of fe(iii)-oxyhydroxides to the oxidation of organic matter in order to conserve energy for growth. several potential mechanisms may be used by s. oneidensis mr-1 to facilitate fe(iii)-reduction. these include direct contact betwee ...201222515480
nitric oxide modulates bacterial biofilm formation through a multicomponent cyclic-di-gmp signaling network.nitric oxide (no) signaling in vertebrates is well characterized and involves the heme-nitric oxide/oxygen-binding (h-nox) domain of soluble guanylate cyclase as a selective no sensor. in contrast, little is known about the biological role or signaling output of bacterial h-nox proteins. here, we describe a molecular pathway for h-nox signaling in shewanella oneidensis. no stimulates biofilm formation by controlling the levels of the bacterial secondary messenger cyclic diguanosine monophosphate ...201222542454
exploring the biochemistry at the extracellular redox frontier of bacterial mineral fe(iii) respiration.many species of the bacterial shewanella genus are notable for their ability to respire in anoxic environments utilizing insoluble minerals of fe(iii) and mn(iv) as extracellular electron acceptors. in shewanella oneidensis, the process is dependent on the decahaem electron-transport proteins that lie at the extracellular face of the outer membrane where they can contact the insoluble mineral substrates. these extracellular proteins are charged with electrons provided by an inter-membrane electr ...201222616858
impact of arca loss in shewanella oneidensis revealed by comparative proteomics under aerobic and anaerobic conditions.shewanella inhabit a wide variety of niches in nature and can utilize a broad spectrum of electron acceptors under anaerobic conditions. how they modulate their gene expression to adapt is poorly understood. arca, homologue of a global regulator controlling hundreds of genes involved in aerobic and anaerobic respiration in e. coli, was shown to be important in aerobiosis/anaerobiosis of s. oneidensis as well. loss of arca, in addition to altering transcription of many genes, resulted in impaired ...201222623420
[microbial fuel cells as an alternative power supply].purpose of the work was designing and prototyping of microbial fuel cells (mfc) and comparative evaluation of the electrogenic activity of wastewater autochthonous microorganisms as well as bacterial monocultures. objects were model electrogenic strain shewanella oneidensis mr-1, and an ochrobactrum sp. strain isolated from the active anode biofilm of mfc composed as an electricity generating system. the study employed the methods typically used for aerobic and anaerobic strains, current measure ...201222629587
detection of transcriptional triggers in the dynamics of microbial growth: application to the respiratorily versatile bacterium shewanella oneidensis.the capacity of microorganisms to respond to variable external conditions requires a coordination of environment-sensing mechanisms and decision-making regulatory circuits. here, we seek to understand the interplay between these two processes by combining high-throughput measurement of time-dependent mrna profiles with a novel computational approach that searches for key genetic triggers of transcriptional changes. our approach helped us understand the regulatory strategies of a respiratorily ve ...201222638572
binding motifs in bacterial gene promoters modulate transcriptional effects of global regulators crp and arca.bacterial gene regulation involves transcription factors (tf) that bind to dna recognition sequences in operon promoters. these recognition sequences, many of which are palindromic, are known as regulatory elements or transcription factor binding sites (tfbs). some tfs are global regulators that can modulate the expression of hundreds of genes. in this study we examine global regulator half-sites, where a half-site, which we shall call a binding motif (bm), is one half of a palindromic tfbs. we ...201222701314
electromicrobiology.electromicrobiology deals with the interactions between microorganisms and electronic devices and with the novel electrical properties of microorganisms. a diversity of microorganisms can donate electrons to, or accept electrons from, electrodes without the addition of artificial electron shuttles. however, the mechanisms for microbe-electrode electron exchange have been seriously studied in only a few microorganisms. shewanella oneidensis interacts with electrodes primarily via flavins that fun ...201222746334
the role of clonal interference in the evolutionary dynamics of plasmid-host adaptation.promiscuous plasmids replicate in a wide range of bacteria and therefore play a key role in the dissemination of various host-beneficial traits, including antibiotic resistance. despite the medical relevance, little is known about the evolutionary dynamics through which drug resistance plasmids adapt to new hosts and thereby persist in the absence of antibiotics. we previously showed that the incompatibility group p-1 (incp-1) minireplicon pms0506 drastically improved its stability in novel host ...201222761390
multistep hopping and extracellular charge transfer in microbial redox chains.dissimilatory metal-reducing bacteria are microorganisms that gain energy by transferring respiratory electrons to extracellular solid-phase electron acceptors. in addition to its importance for physiology and natural environmental processes, this form of metabolism is being investigated for energy conversion and fuel production in bioelectrochemical systems, where microbes are used as biocatalysts at electrodes. one proposed strategy to accomplish this extracellular charge transfer involves for ...201222797729
transcriptome analysis of early surface-associated growth of shewanella oneidensis mr-1.bacterial biofilm formation starts with single cells attaching to a surface, however, little is known about the initial attachment steps and the adaptation to the surface-associated life style. here, we describe a hydrodynamic system that allows easy harvest of cells at very early biofilm stages. using the metal ion-reducing gammaproteobacterium shewanella oneidensis mr-1 as a model organism, we analyzed the transcriptional changes occurring during surface-associated growth between 15 and 60 min ...201222860070
[creation of mutants of shewanella oneidensis mr-1 with increased reduction activity]. 201722880395
promiscuous cross-seeding between bacterial amyloids promotes interspecies biofilms.amyloids are highly aggregated proteinaceous fibers historically associated with neurodegenerative conditions including alzheimers, parkinsons, and prion-based encephalopathies. polymerization of amyloidogenic proteins into ordered fibers can be accelerated by preformed amyloid aggregates derived from the same protein in a process called seeding. seeding of disease-associated amyloids and prions is highly specific and cross-seeding is usually limited or prevented. here we describe the first stud ...201222891247
identifying metalloproteins through x-ray fluorescence mapping and mass spectrometry.metals are critical and dynamic components of biochemistry. to understand their roles, we greatly need tools to identify the ligands that bind them within the complexity of natural systems. this work describes the development of methods that not only detect and distinguish metals, but also characterize the proteins that bind them. we describe an approach to expose, identify and quantify metalloproteins in complex mixtures by sequential non-denaturing 2d-gel electrophoresis (2d ge)/x-ray fluoresc ...201222903313
biofilm shows spatially stratified metabolic responses to contaminant exposure.biofilms are core to a range of biological processes, including the bioremediation of environmental contaminants. within a biofilm population, cells with diverse genotypes and phenotypes coexist, suggesting that distinct metabolic pathways may be expressed based on the local environmental conditions in a biofilm. however, metabolic responses to local environmental conditions in a metabolically active biofilm interacting with environmental contaminants have never been quantitatively elucidated. i ...201222925136
anomalies of the anaerobic tricarboxylic acid cycle in shewanella oneidensis revealed by tn-seq.the availability of increasingly inexpensive sequencing combined with an ever-expanding molecular biology toolbox has transported classical bacterial genetics into the 21st century. whole genome genetic fitness analysis using transposon mutagenesis combined with next-generation high-throughput sequencing (tn-seq) promises to revolutionize systems level analysis of microbial metabolism. tn-seq measures the frequency of actual members of a heterogeneous mutant pool undergoing purifying selection t ...201222925268
molecular and logic gate based on bacterial anaerobic respiration.enzyme coding genes that integrate information for anaerobic respiration in shewanella oneidensis mr-1 were used as input for constructing an and logic gate. the absence of one or both genes inhibited electrochemically-controlled anaerobic respiration, while wild type bacteria were capable of accepting electrons from an electrode for dmso reduction.201222932878
intracellularly grown gold nanoislands as sers substrates for monitoring chromate, sulfate and nitrate localization sites in remediating bacteria biofilms by raman chemical imaging.understanding the chemical composition of biofilm matrices is vital in different fields of biology such as surgery, dental medicine, synthetic grafts and bioremediation. the knowledge of biofilm development, composition, active reduction sites and remediation efficacy will help in the development of effective solutions and evaluation of remediating approaches prior to implementation. surface-enhanced raman spectroscopy (sers) based imaging is an invaluable tool to obtain an understanding of the ...201222938600
the effect of the encapsulation of bacteria in redox phospholipid polymer hydrogels on electron transfer efficiency in living cell-based devices.development of living cell-based devices holds great promise in many biomedical and industrial applications. to increase our understanding of the process, we investigated the biological and electrochemical properties of a redox phospholipid polymer hydrogel containing an electron-generating bacteria (shewanella oneidensis mr-1). a water-soluble and amphiphilic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate-co-p-vinylphenylboronic acid-co-vinylferrocen ...201222938764
improved microbial electrocatalysis with osmium polymer modified electrodes.using the well-known exoelectrogen shewanella oneidensis mr-1, an osmium redox polymer modified anode exhibited ca. 4-fold increase in current generation. additionally, a significant decrease in the start-up time for electrocatalysis was observed. the findings suggest that the inherent extracellular electron transfer capabilities of electrogens coupled with such polymers could enhance electrocatalysis.201222968325
redox reactions of reduced flavin mononucleotide (fmn), riboflavin (rbf), and anthraquinone-2,6-disulfonate (aqds) with ferrihydrite and lepidocrocite.flavins are secreted by the dissimilatory iron-reducing bacterium shewanella and can function as endogenous electron transfer mediators. to assess the potential importance of flavins in fe(iii) bioreduction, we investigated the redox reaction kinetics of reduced flavin mononucleotide (i.e., fmnh(2)) and reduced riboflavin (i.e., rbfh(2)) with ferrihydrite and lepidocrocite. the organic reductants rapidly reduced and dissolved ferrihydrite and lepidocrocite in the ph range 4-8. the rate constant ...201222985396
regulatory network operations in the pathway tools software.biologists are elucidating complex collections of genetic regulatory data for multiple organisms. software is needed for such regulatory network data.201222998532
preferential utilization of d-lactate by shewanella oneidensis.shewanella oneidensis couples oxidation of lactate to respiration of many substrates. here we report that llpr (l-lactate-positive regulator, so_3460) encodes a positive regulator of l-lactate utilization distinct from previously studied regulators. we also demonstrate d-lactate inhibition of l-lactate utilization in s. oneidensis, resulting in preferential utilization of the d isomer.201223001660
comparative multi-goal tradeoffs in systems engineering of microbial metabolism.metabolic engineering design methodology has evolved from using pathway-centric, random and empirical-based methods to using systems-wide, rational and integrated computational and experimental approaches. persistent during these advances has been the desire to develop design strategies that address multiple simultaneous engineering goals, such as maximizing productivity, while minimizing raw material costs.201223009214
dynamic modeling of aerobic growth of shewanella oneidensis. predicting triauxic growth, flux distributions, and energy requirement for growth.a model-based analysis is conducted to investigate metabolism of shewanella oneidensis mr-1 strain in aerobic batch culture, which exhibits an intriguing growth pattern by sequentially consuming substrate (i.e., lactate) and by-products (i.e., pyruvate and acetate). a general protocol is presented for developing a detailed network-based dynamic model for s. oneidensis based on the lumped hybrid cybernetic model (l-hcm) framework. the l-hcm, although developed from only limited data, is shown to ...201323022551
expression of shewanella oneidensis mr-1 [fefe]-hydrogenase genes in anabaena sp. strain pcc 7120.h(2) generated from renewable resources holds promise as an environmentally innocuous fuel that releases only energy and water when consumed. in biotechnology, photoautotrophic oxygenic diazotrophs could produce h(2) from water and sunlight using the cells' endogenous nitrogenases. however, nitrogenases have low turnover numbers and require large amounts of atp. [fefe]-hydrogenases found in other organisms can have 1,000-fold higher turnover numbers and no specific requirement for atp but are ve ...201223023750
biological accumulation of tellurium nanorod structures via reduction of tellurite by shewanella oneidensis mr-1.the dissimilatory metal-reducing bacterium, shewanella oneidensis mr-1, reduced tellurite (te(iv), teo(3)(2-)) to elemental tellurium under anaerobic conditions resulting in the intracellular accumulation of needle shaped crystalline te(0) nanorods. fatty acid analyses showed that toxic te(iv) increased the unsaturated fatty acid composition of the lipid components of the cell membrane, implying a deconstruction of the integrity of the cellular membrane structure. the current results suggest tha ...201223026324
decolorization and detoxification of a sulfonated triphenylmethane dye aniline blue by shewanella oneidensis mr-1 under anaerobic conditions.in this work, the extracellular decolorization of aniline blue, a sulfonated triphenylmethane dye, by shewanella oneidensis mr-1 was confirmed. s. oneidensis mr-1 showed a high capacity for decolorizing aniline blue even at a concentration of up to 1,000 mg/l under anaerobic conditions. maximum decolorization efficiency appeared at ph 7.0 and 30 °c. lactate was a better candidate of electron donor for the decolorization of aniline blue. the addition of nitrate, hydrous ferric oxide, or trimethyl ...201323053116
mind the gap: cytochrome interactions reveal electron pathways across the periplasm of shewanella oneidensis mr-1.extracellular electron transfer is the key metabolic trait that enables some bacteria to play a significant role in the biogeochemical cycling of metals and in bioelectrochemical devices such as microbial fuel cells. in shewanella oneidensis mr-1, electrons generated in the cytoplasm by catabolic processes must cross the periplasmic space to reach terminal oxidoreductases found at the cell surface. lack of knowledge on how these electrons flow across the periplasmic space is one of the unresolve ...201323067389
urocanate reductase: identification of a novel anaerobic respiratory pathway in shewanella oneidensis mr-1.interpretation of the constantly expanding body of genomic information requires that the function of each gene be established. here we report the genomic analysis and structural modelling of a previously uncharacterized redox-metabolism protein urda (so_4620) of shewanella oneidensis mr-1, which led to a discovery of the novel enzymatic activity, urocanate reductase. further cloning and expression of urda, as well as purification and biochemical study of the gene's product urda and redox titrati ...201223078170
metabolic footprinting of mutant libraries to map metabolite utilization to genotype.the discrepancy between the pace of sequencing and functional characterization of genomes is a major challenge in understanding complex microbial metabolic processes and metabolic interactions in the environment. here, we identified and validated genes related to the utilization of specific metabolites in bacteria by profiling metabolite utilization in libraries of mutant strains. untargeted mass spectrometry based metabolomics was used to identify metabolites utilized by escherichia coli and sh ...201323082955
characterization of an efficient catalytic and organic solvent-tolerant azoreductase toward methyl red from shewanella oneidensis mr-1.the acyl carrier protein (acp) phosphodiesterase gene (so 4396) of shewanella oneidensis mr-1 which was analyzed to have azoreductase activity was heterologously expressed in escherichia coli. the acp phosphodiesterase was found to reach maximum enzyme velocity 220.59 u/mg, named azoreductase in this study. the azoreductase had highest specific activity (153.16 u/mg) at ph 6.5, which showed a preference for nicotinamide adenine dinucleotide (nadh) as electron donor. the phylogenetic tree analysi ...201323089953
comparison of bacterial cells and amine-functionalized abiotic surfaces as support for pd nanoparticle synthesis.an increasing demand for catalytic pd nanoparticles has motivated the search for sustainable production methods. an innovative approach uses bacterial cells as support material for synthesizing pd nanoparticles by reduction of pd(ii) with e.g. hydrogen or formate. nevertheless, drawbacks of microbially supported pd catalysts are the low catalytic activity compared to conventional pd nanocatalysts and the possible poisoning of the catalyst surface by sulfur originating from bacterial proteins. a ...201323107967
probing the putative active site of yjdl: an unusual proton-coupled oligopeptide transporter from e. coli.yjdl from e. coli is an unusual proton-coupled oligopeptide transporter (pot). unlike prototypical pots, dipeptides are preferred over tripeptides, in particular dipeptides with a positively charged c-terminal residue. to further understand this difference in peptide specificity, the sequences of yjdl and ydgr, a prototypical e. coli pot, were compared in light of the crystal structure of a pot from shewanella oneidensis. several residues found in the putative active site were mutated and the ac ...201223110099
ferric iron enhances electricity generation by shewanella oneidensis mr-1 in mfcs.fe(iii) supplemented into microbial fuel cells (mfc) at initial start-up increased electricity generation by shewanella oneidensis mr-1. the maximum power density reached 158.1 mw/m(2) with 6 mm fe(iii), compared with 73.9 mw/m(2) without fe(iii). a significant increase in power output was observed when mfc with established biofilm in the absence of fe(iii) was supplemented with fe(iii) afterward. the cell biomass of the anode biofilm of mfcs operated in the presence of fe(iii) was higher than t ...201323127834
crystallization of uridine phosphorylase from shewanella oneidensis mr-1 in the laboratory and under microgravity and preliminary x-ray diffraction analysis.uridine phosphorylase (udp, ec 2.4.2.3), a key enzyme in the pyrimidine salvage pathway, catalyses the reversible phosphorolysis of uridine to uracil and ribose 1-phosphate. the gene expression of udp from shewanella oneidensis mr-1 was performed in the recipient strain escherichia coli. the udp protein was crystallized on earth (in the free form and in complex with uridine as the substrate) by the hanging-drop vapour-diffusion method at 296 k and under microgravity conditions (in the free form) ...201223143255
domain analysis of arcs, the hybrid sensor kinase of the shewanella oneidensis mr-1 arc two-component system, reveals functional differentiation of its two receiver domains.in all species of the genus shewanella, the redox-sensing arc two-component system consists of the response regulator arca, the sensor kinase arcs, and the separate phosphotransfer protein hpta. compared to its counterpart arcb in escherichia coli, arcs has a significantly different domain structure. resequencing and reannotation revealed that in the n-terminal part, arcs possesses a periplasmic cache-sensing domain bracketed by two transmembrane domains and, moreover, that arcs has two cytoplas ...201323161031
shewanella oneidensis mr-1 chemotaxis proteins and electron-transport chain components essential for congregation near insoluble electron acceptors.shewanella oneidensis mr-1 cells utilize a behaviour response called electrokinesis to increase their speed in the vicinity of ieas (insoluble electron acceptors), including manganese oxides, iron oxides and poised electrodes [harris, el-naggar, bretschger, ward, romine, obraztsova and nealson (2010) proc. natl. acad. sci. u.s.a. 107, 326-331]. however, it is not currently understood how bacteria remain in the vicinity of the iea and accumulate both on the surface and in the surrounding medium. ...201223176449
analysis of structural mtrc models based on homology with the crystal structure of mtrf.the outer-membrane decahaem cytochrome mtrc is part of the transmembrane mtrcab complex required for mineral respiration by shewanella oneidensis. mtrc has significant sequence similarity to the paralogous decahaem cytochrome mtrf, which has been structurally solved through x-ray crystallography. this now allows for homology-based models of mtrc to be generated. the structure of these mtrc homology models contain ten bis-histidine-co-ordinated c-type haems arranged in a staggered cross through a ...201223176451
comparative c-type cytochrome expression analysis in shewanella oneidensis strain mr-1 and anaeromyxobacter dehalogenans strain 2cp-c grown with soluble and insoluble oxidized metal electron acceptors.the genomes of shewanella oneidensis strain mr-1 and anaeromyxobacter dehalogenans strain 2cp-c encode 40 and 69 putative c-type cytochrome genes respectively. deletion mutant and biochemical studies have assigned specific functions to a few c-type cytochromes involved in electron transfer to oxidized metals in s. oneidensis strain mr-1. although promising, the genetic approach is limited to gene deletions that produce a distinct phenotype and to an organism for which a genetic system is availab ...201223176455
the roles of cyma in support of the respiratory flexibility of shewanella oneidensis mr-1.shewanella species are isolated from the oxic/anoxic regions of seawater and aquatic sediments where redox conditions fluctuate in time and space. colonization of these environments is by virtue of flexible respiratory chains, many of which are notable for the ability to reduce extracellular substrates including the fe(iii) and mn(iv) contained in oxide and phyllosilicate minerals. shewanella oneidensis mr-1 serves as a model organism to consider the biochemical basis of this flexibility. in the ...201223176457
development of a proteoliposome model to probe transmembrane electron-transfer reactions.the mineral-respiring bacterium shewanella oneidensis uses a protein complex, mtrcab, composed of two decahaem cytochromes brought together inside a transmembrane porin to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. a proteoliposome system has been developed that contains methyl viologen as an internalized electron carrier and valinomycin as a membrane-associated cation exchanger. these proteoliposomes can be used as a model system to investiga ...201223176464
mtr extracellular electron-transfer pathways in fe(iii)-reducing or fe(ii)-oxidizing bacteria: a genomic perspective.originally discovered in the dissimilatory metal-reducing bacterium shewanella oneidensis mr-1 (mr-1), key components of the mtr (i.e. metal-reducing) pathway exist in all strains of metal-reducing shewanella characterized. the protein components identified to date for the mtr pathway of mr-1 include four multihaem c-cyts (c-type cytochromes), cyma, mtra, mtrc and omca, and a porin-like outer membrane protein mtrb. they are strategically positioned along the width of the mr-1 cell envelope to me ...201223176465
mind the gap: diversity and reactivity relationships among multihaem cytochromes of the mtra/dmse family.shewanella oneidensis mr-1 has the ability to use many external terminal electron acceptors during anaerobic respiration, such as dmso. the pathway that facilitates this electron transfer includes the decahaem cytochrome dmse, a paralogue of the mtra family of decahaem cytochromes. although both dmse and mtra are decahaem cytochromes implicated in the long-range electron transfer across a ~300 å (1 å=0.1 nm) wide periplasmic 'gap', mtra has been shown to be only 105 å in maximal length. in the p ...201223176466
the quest to achieve the detailed structural and functional characterization of cyma.shewanella oneidensis mr-1 is a sediment organism capable of dissimilatory reduction of insoluble metal compounds such as those of fe(ii) and mn(iv). this bacterium has been used as a model organism for potential applications in bioremediation of contaminated environments and in the production of energy in microbial fuel cells. the capacity of shewanella to perform extracellular reduction of metals is linked to the action of several multihaem cytochromes that may be periplasmic or can be associa ...201223176470
recent advances in structural biology of peptide transporters.peptide transporters localized at brush-border membranes of intestinal and renal epithelial cells mediate the membrane transport of di- and tripeptides, and play important roles in protein absorption and the conservation of peptide-bound amino nitrogen. peptide-like drugs that show structural similarities to di- and tripeptides are also recognized by peptide transporters. the energy for transport of small peptides and peptide-like drugs is provided by the proton gradient across the cell membrane ...201223177989
impact of quaternary structure upon bacterial cytochrome c peroxidases: does homodimerization matter?all known active forms of diheme bacterial cytochrome c peroxidase (bccp) enzymes are described by a homodimeric state. further, the majority of bccps reported display activity only when the high-potential electron transfer heme of the protein (fe(h)) is reduced to the ferrous oxidation state. reduction of fe(h) results in a set of conformational changes allowing for the low-potential peroxidatic heme (fe(l)) to adopt a high-spin, five-coordinate state that is capable of binding substrate. here ...201223189923
power generation from a hybrid biological fuel cell in seawater.a hybrid biological fuel cell (hbfc) comprised of a microbial anode for lactate oxidation and an enzymatic cathode for oxygen reduction was constructed and then tested in a marine environment. shewanella oneidensis dsp-10 was cultivated in laboratory medium and then fixed on a carbon felt electrode via a silica sol-gel process in order to catalyze anodic fuel cell processes. the cathode electrocatalyst was composed of bilirubin oxidase, fixed to a carbon nanotube electrode using a heterobifuncti ...201323196242
temporal expression-based analysis of metabolism.metabolic flux is frequently rerouted through cellular metabolism in response to dynamic changes in the intra- and extra-cellular environment. capturing the mechanisms underlying these metabolic transitions in quantitative and predictive models is a prominent challenge in systems biology. progress in this regard has been made by integrating high-throughput gene expression data into genome-scale stoichiometric models of metabolism. here, we extend previous approaches to perform a temporal express ...201223209390
direct electrochemistry of shewanella oneidensis cytochrome c nitrite reductase: evidence of interactions across the dimeric interface.shewanella oneidensis cytochrome c nitrite reductase (sonrfa), a dimeric enzyme that houses five c-type hemes per protomer, conducts the six-electron reduction of nitrite and the two-electron reduction of hydroxylamine. protein film voltammetry (pfv) has been used to study the cytochrome c nitrite reductase from escherichia coli (ecnrfa) previously, revealing catalytic reduction of both nitrite and hydroxylamine substrates by ecnrfa adsorbed to a graphite electrode that is characterized by "boos ...201223210513
genomic plasticity enables a secondary electron transport pathway in shewanella oneidensis.microbial dissimilatory iron reduction is an important biogeochemical process. it is physiologically challenging because iron occurs in soils and sediments in the form of insoluble minerals such as hematite or ferrihydrite. shewanella oneidensis mr-1 evolved an extended respiratory chain to the cell surface to reduce iron minerals. interestingly, the organism evolved a similar strategy for reduction of dimethyl sulfoxide (dmso), which is reduced at the cell surface as well. it has already been e ...201323220953
patterned hydrophobic domains in the exopolymer matrix of shewanella oneidensis mr-1 biofilms.water-dispersible amphiphilic surface-engineered quantum dots (qds) were found to be strongly accumulated within discrete zones of the exopolymer network of shewanella oneidensis mr-1 biofilms, but not on the cell surfaces. these microdomains showed a patterned distribution in the exopolymer matrix, which led to a restricted diffusion of the amphiphilic nanoparticles.201323220957
a crp-dependent two-component system regulates nitrate and nitrite respiration in shewanella oneidensis.we have previously illustrated the nitrate/nitrite respiratory pathway of shewanella oneidensis, which is renowned for its remarkable versatility in respiration. here we investigated the systems regulating the pathway with a reliable approach which enables characterization of mutants impaired in nitrate/nitrite respiration by guaranteeing biomass. the s. oneidensis genome encodes an escherichia coli narq/narx homolog so3981 and two e. coli narp/narl homologs so1860 and so3982. results of physiol ...201223240049
single-cell imaging and spectroscopic analyses of cr(vi) reduction on the surface of bacterial cells.we investigate the single-cell reduction of toxic cr(vi) by the dissimilatory metal-reducing bacterium shewanella oneidensis mr-1 (mr-1), an important bioremediation process, using raman spectroscopy and scanning electron microscopy (sem) combined with energy-dispersive x-ray spectroscopy (edx). our experiments indicate that the toxic, highly soluble cr(vi) can be efficiently reduced to less toxic, nonsoluble cr(2)o(3) nanoparticles by mr-1. cr(2)o(3) is observed to emerge as nanoparticles adsor ...201323249294
inference of gene regulatory networks from genome-wide knockout fitness data.genome-wide fitness is an emerging type of high-throughput biological data generated for individual organisms by creating libraries of knockouts, subjecting them to broad ranges of environmental conditions, and measuring the resulting clone-specific fitnesses. since fitness is an organism-scale measure of gene regulatory network behaviour, it may offer certain advantages when insights into such phenotypical and functional features are of primary interest over individual gene expression. previous ...201323271269
flavin electron shuttles dominate extracellular electron transfer by shewanella oneidensis.shewanella oneidensis strain mr-1 is widely studied for its ability to respire a diverse array of soluble and insoluble electron acceptors. the ability to breathe insoluble substrates is defined as extracellular electron transfer and can occur via direct contact or by electron shuttling in s. oneidensis. to determine the contribution of flavin electron shuttles in extracellular electron transfer, a transposon mutagenesis screen was performed with s. oneidensis to identify mutants unable to secre ...201323322638
concentration responses of toxicity sensor with shewanella oneidensis mr-1 growing in bioelectrochemical systems.bioelectrochemical systems (bess) provide an opportunity to detect biological toxicity of water samples. however, the concentration responses of toxins had not been investigated in detail. using formaldehyde as a toxic substance, the current responses were analyzed over a concentration range from 0.01% to 0.10% in a single chambered bes with 0mv (versus saturated calomel electrode) applied on the anode. the decay percentages of currents increased in proportion with the concentration of formaldeh ...201323333921
exoprotein production correlates with morphotype changes of nonmotile shewanella oneidensis mutants.we report a previously undescribed mechanism for the rugose morphotype in shewanella oneidensis, a research model for investigating redox transformations of environmental contaminants. bacteria may form smooth or rugose colonies on agar plates. in general, conversion from the smooth to rugose colony morphotype is attributed to increased production of exopolysaccharide (eps). in this work, we discovered that aflagellate s. oneidensis mutants grew into rugose colonies, whereas those with nonfuncti ...201323335418
inward-facing conformation of the zinc transporter yiip revealed by cryoelectron microscopy.yiip is a dimeric zn(2+)/h(+) antiporter from escherichia coli belonging to the cation diffusion facilitator family. we used cryoelectron microscopy to determine a 13-å resolution structure of a yiip homolog from shewanella oneidensis within a lipid bilayer in the absence of zn(2+). starting from the x-ray structure in the presence of zn(2+), we used molecular dynamics flexible fitting to build a model consistent with our map. comparison of the structures suggests a conformational change that in ...201323341604
increase of riboflavin biosynthesis underlies enhancement of extracellular electron transfer of shewanella in alkaline microbial fuel cells.electrolyte ph tremendously affects the electricity output of microbial fuel cells. however, its underlying molecular mechanism remains elusive, in particular for shewanella oneidensis mr-1, one of the most widely adopted electrogenic microorganisms. herein, we found that mfcs were able to deliver a significant (but different) electricity output in a wide range of ph (from 6 to 10), with the maximum at ph=9 (alkaline), which delivers ∼1.5times' higher power output than that at ph=7 (neutral). fu ...201323353587
influence of outer membrane c-type cytochromes on particle size and activity of extracellular nanoparticles produced by shewanella oneidensis.the metal-reducing bacterium shewanella oneidensis is capable of reducing various metal(loid)s and produces nanoparticles (nps) extracellularly, in which outer membrane c-type cytochromes (omcs) have been suggested to play important roles. the objective of this study was to investigate the influence of the omcs, that is, mtrc and omca, on the size and activity of the extracellular silver nps (agnps) and silver sulfide nps (ag(2)s nps) produced by s. oneidensis mr-1. we found that (i) the lack of ...201323381725
shewanella oneidensis hfq promotes exponential phase growth, stationary phase culture density, and cell survival.hfq is an rna chaperone protein that has been broadly implicated in srna function in bacteria. here we describe the construction and characterization of a null allele of the gene that encodes the rna chaperone hfq in shewanella oneidensis strain mr-1, a dissimilatory metal reducing bacterium.201323394078
electrospun carbon nanofibers from polyacrylonitrile blended with activated or graphitized carbonaceous materials for improving anodic bioelectrocatalysis.the electrospun carbon nanofibers obtained from polyacrylonitrile (pan) and pan blends with either activated carbon (pan-ac) or graphite (pan-gr) were tested as anodes using shewanella oneidensis mr-1. extensive physico-chemical and electrochemical characterization confirmed their formation, their fibrous and porous nature, and their suitability as electrodes. n2 adsorption measurements revealed high specific surface area (229.8, 415.8 and 485.2m(2) g(-1)) and porosity (0.142, 0.202 and 0.239cm( ...201323399497
the origin of 8-amino-3,8-dideoxy-d-manno-octulosonic acid (kdo8n) in the lipopolysaccharide of shewanella oneidensis.lipopolysaccharide (lps; endotoxin) is an essential component of the outer monolayer of nearly all gram-negative bacteria. lps is composed of a hydrophobic anchor, known as lipid a, an inner core oligosaccharide, and a repeating o-antigen polysaccharide. in nearly all species, the first sugar bridging the hydrophobic lipid a and the polysaccharide domain is 3-deoxy-d-manno-octulosonic acid (kdo), and thus it is critically important for lps biosynthesis. modifications to lipid a have been shown t ...201323413030
crp-dependent cytochrome bd oxidase confers nitrite resistance to shewanella oneidensis.shewanella oneidensis is able to respire on a variety of organic and inorganic substrates, including nitrate and nitrite. conversion of nitrate to nitrite and nitrite to ammonium is catalysed by periplasmic nitrate and nitrite reductases (nap and nrf) respectively. global regulator crp (cyclic amp receptor protein) is essential for growth of s. oneidensis on both nitrate and nitrite. in this study, we discovered that crp mutants are not only severely deficient in nitrate or nitrite respiration, ...201323414111
diffusion in biofilms respiring on electrodes.the goal of this study was to measure spatially and temporally resolved effective diffusion coefficients (d(e)) in biofilms respiring on electrodes. two model electrochemically active biofilms, geobacter sulfurreducens pca and shewanella oneidensis mr-1, were investigated. a novel nuclear magnetic resonance microimaging perfusion probe capable of simultaneous electrochemical and pulsed-field gradient nuclear magnetic resonance (pfg-nmr) techniques was used. pfg-nmr allowed noninvasive, nondestru ...201323420623
enhanced performance of hexavalent chromium reducing cathodes in the presence of shewanella oneidensis mr-1 and lactate.biocathodes for the reduction of the highly toxic hexavalent chromium (cr(vi)) were investigated using shewanella oneidensis mr-1 (mr-1) as a biocatalyst and performance was assessed in terms of current production and cr(vi) reduction. potentiostatically controlled experiments (-500 mv vs ag/agcl) showed that a mediatorless mr-1 biocathode started up under aerated conditions in the presence of lactate, received 5.5 and 1.7 times more electrons for cr(vi) reduction over a 4 h operating period tha ...201323517384
rapid electron exchange between surface-exposed bacterial cytochromes and fe(iii) minerals.the mineral-respiring bacterium shewanella oneidensis uses a protein complex, mtrcab, composed of two decaheme cytochromes, mtrc and mtra, brought together inside a transmembrane porin, mtrb, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. a proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the mtrcab complex relates to its ability to transport electrons across a lipid bilayer t ...201323538304
accelerated removal of sudan dye by shewanella oneidensis mr-1 in the presence of quinones and humic acids.although there have been many studies on bacterial removal of soluble azo dyes, much less information is available for biological treatment of water-insoluble azo dyes. the few bacterial species capable of removing sudan dye generally require a long time to remove low concentrations of insoluble dye particles. the present work examined the efficient removal of sudan i by shewanella oneidensis mr-1 in the presence of redox mediator. it was found that the microbially reduced anthraquinone-2,6-disu ...201323539152
posttranslational modification of flagellin flab in shewanella oneidensis.shewanella oneidensis is a highly motile organism by virtue of a polar, glycosylated flagellum composed of flagellins flaa and flab. in this study, the functional flagellin flab was isolated and analyzed with nano-liquid chromatography-mass spectrometry (ms) and tandem ms. in combination with the mutational analysis, we propose that the flab flagellin protein from s. oneidensis is modified at five serine residues with a series of novel o-linked posttranslational modifications (ptms) that differ ...201323543712
investigating the structural dependence of protein stabilization by amino acid substitution.a goal of protein engineering technology is developing methods to increase protein stability. however, rational design of stable proteins is difficult because the stabilization mechanism of proteins is not fully understood. in this study, we examined the structural dependence of protein stabilization by introducing single amino acid substitution into ribonuclease h1 from the psychotropic bacterium shewanella oneidensis mr-1 (so-rnase h1), which was our model protein. we performed saturation muta ...201323547982
expression of blaa underlies unexpected ampicillin-induced cell lysis of shewanella oneidensis.shewanella oneidensis is a facultative anaerobic γ-proteobacterium possessing remarkably diverse respiratory capacities for reducing various organic and inorganic substrates. as a veteran research model for investigating redox transformations of environmental contaminants the bacterium is well known to be a naturally ampicillin-resistant microorganism. however, in this study we discovered that ampicillin has a significant impact on growth of s. oneidensis. particularly, cell lysis occurred only ...201323555975
electron acceptor dependence of electron shuttle secretion and extracellular electron transfer by shewanella oneidensis mr-1.shewanella oneidensis mr-1 is an extensively studied dissimilatory metal-reducing bacterium with a great potential for bioremediation and electricity generation. it secretes flavins as electron shuttles which play an important role in extracellular electron transfer. however, the influence of various environmental factors on the secretion of flavins is largely unknown. here, the effects of electron acceptors, including fumarate, ferrihydrite, fe(iii)-nitrilotriacetic acid (nta), nitrate and trim ...201323558182
phenothiazine derivative-accelerated microbial extracellular electron transfer in bioelectrochemical system.in bioelectrochemical system (bes) the extracellular electron transfer (eet) from bacteria to anode electrode is recognized as a crucial step that governs the anodic reaction efficiency. here, we report a novel approach to substantially enhance the microbial eet by immobilization of a small active phenothiazine derivative, methylene blue, on electrode surface. a comparison of the currents generated by shewanella oneidensis mr-1 and its mutants as well as the electrochemical analytical results re ...201323563590
iron and copper act synergistically to delay anaerobic growth of bacteria.transition metals are known to cause toxic effects through their interaction with oxygen, but toxicity under anoxic conditions is poorly understood. here we investigated the effects of iron (fe) and copper (cu) on the anaerobic growth and gene expression of the purple phototrophic bacterium rhodopseudomonas palustris tie-1. we found that fe(ii) and cu(ii) act synergistically to delay anaerobic growth at environmentally relevant metal concentrations. cu(i) and cu(ii) had similar effects both alon ...201323563938
role of electricity production in the anaerobic decolorization of dye mixture by exoelectrogenic bacterium shewanella oneidensis mr-1.this study investigated the anaerobic decolorization of the dye mixture containing methyl orange (mo) and naphthol green b (ngb) by shewanella oneidensis mr-1. s. oneidensis mr-1 showed a strong ability to decolorize the dye mixture. mo was easier to get the electrons and inhibited the reduction of ngb, despite of its lower redox potential than ngb. the mtr respiratory pathway played an important role in this process. meantime, addition of extracellular electron shuttles accelerated the decolori ...201323567679
rate enhancement of bacterial extracellular electron transport involves bound flavin semiquinones.extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. here we show that flavin molecules secreted by shewanella oneidensis mr-1 enhance the ability of its outer-membrane c-type cytochromes (om c-cyts) to transport electrons as redox cofactors, but not free-form flavins. whole-cell ...201323576738
proof of principle for an engineered microbial biosensor based on shewanella oneidensis outer membrane protein complexes.shewanella oneidensis is known for its ability to respire on extracellular electron acceptors. the spectrum of these acceptors also includes anode surfaces. based on this activity, a versatile s. oneidensis based biosensor strain was constructed in which electricity production can be modulated. construction started with the identification of a usable rate-limiting step of electron transfer to an anode. thereafter, the sensor strain was genetically engineered to produce a protein complex consisti ...201323584391
indirect and suboptimal control of gene expression is widespread in bacteria.gene regulation in bacteria is usually described as an adaptive response to an environmental change so that genes are expressed when they are required. we instead propose that most genes are under indirect control: their expression responds to signal(s) that are not directly related to the genes' function. indirect control should perform poorly in artificial conditions, and we show that gene regulation is often maladaptive in the laboratory. in shewanella oneidensis mr-1, 24% of genes are detrim ...201323591776
mislocalization of rieske protein peta predominantly accounts for the aerobic growth defect of tat mutants in shewanella oneidensis.shewanella oneidensis exhibits a remarkable versatility in respiration, which largely relies on its various respiratory pathways. most of these pathways are composed of secretory terminal reductases and multiple associated electron transport proteins that contain cofactors such as fe-s, molybdopterin, and nife. the majority of these cofactors are inserted enzymatically in the cytoplasm, and thus are substrates of the twin-arginine translocation (tat) protein export system, which transports fully ...201323593508
impacts of nitrate and nitrite on physiology of shewanella oneidensis.shewanella oneidensis exhibits a remarkable versatility in anaerobic respiration, which largely relies on its diverse respiratory pathways. some of these are expressed in response to the existence of their corresponding electron acceptors (eas) under aerobic conditions. however, little is known about respiration and the impact of non-oxygen eas on the physiology of the microorganism when oxygen is present. here we undertook a study to elucidate the basis for nitrate and nitrite inhibition of gro ...201323626841
electrochemical analysis of shewanella oneidensis engineered to bind gold electrodes.growth in three-electrode electrochemical cells allows quantitative analysis of mechanisms involved in electron flow from dissimilatory metal reducing bacteria to insoluble electron acceptors. in these systems, gold electrodes are a desirable surface to study the electrophysiology of extracellular respiration, yet previous research has shown that certain shewanella species are unable to form productive biofilms on gold electrodes. to engineer attachment of shewanella oneidensis to gold, five rep ...201223656372
tuning promoter strengths for improved synthesis and function of electron conduits in escherichia coli.introduction of the electron transfer complex mtrcab from shewanella oneidensis mr-1 into a heterologous host provides a modular and molecularly defined route for electrons to be transferred to an extracellular inorganic solid. however, an escherichia coli strain expressing this pathway displayed limited control of mtrcab expression and impaired cell growth. to overcome these limitations and to improve heterologous extracellular electron transfer, we used an e. coli host with a more tunable indu ...201323656438
bacterial recognition of silicon nanowire arrays.understanding how living cells interact with nanostructures is integral to a better understanding of the fundamental principles of biology and the development of next-generation biomedical/bioenergy devices. recent studies have demonstrated that mammalian cells can recognize nanoscale topographies and respond to these structures. from this perspective, there is a growing recognition that nanostructures, along with their specific physicochemical properties, can also be used to regulate the respon ...201323682751
impact of tio2 nanoparticles on growth, biofilm formation, and flavin secretion in shewanella oneidensis.understanding of nanoparticle impacts on critical bacteria functions allows us to gain a mechanistic understanding of toxicity and guides us toward design rules for creating safe nanomaterials. herein, biofilm formation, a general bacteria function, and riboflavin secretion, a species-specific function, were monitored in shewanella oneidensis, a metal reducing bacterium, following exposure to a variety of tio2 nanoparticle types (synthesized, aeroxide p25, and t-eco). transmission electron micro ...201323701037
shewanella oneidensis mr-1 bacterial nanowires exhibit p-type, tunable electronic behavior.the study of electrical transport in biomolecular materials is critical to our fundamental understanding of physiology and to the development of practical bioelectronics applications. in this study, we investigated the electronic transport characteristics of shewanella oneidensis mr-1 nanowires by conducting-probe atomic force microscopy (cp-afm) and by constructing field-effect transistors (fets) based on individual s. oneidensis nanowires. here we show that s. oneidensis nanowires exhibit p-ty ...201323701405
the mxd operon in shewanella oneidensis mr-1 is induced in response to starvation and regulated by arcs/arca and bara/uvry.s. oneidensis mr-1 is a dissimilatory metal-reducing bacterium. under anoxic conditions s. oneidensis mr-1 attaches to and uses insoluble minerals such as fe(iii) and mn(iv) oxides as electron acceptors. in the laboratory, s. oneidensis mr-1 forms biofilms under hydrodynamic flow conditions on a borosilicate glass surface; formation of biofilms was previously found to be dependent on the mxd gene cluster (mxdabcd).201323705927
effects of the anaerobic respiration of shewanella oneidensis mr-1 on the stability of extracellular u(vi) nanofibers.uranium (vi) is considered to be one of the most widely dispersed and problematic environmental contaminants, due in large part to its high solubility and great mobility in natural aquatic systems. we previously reported that under anaerobic conditions, shewanella oneidensis mr-1 grown in medium containing uranyl acetate rapidly accumulated long, extracellular, ultrafine u(vi) nanofibers composed of polycrystalline chains of discrete meta-schoepite (uo(3)·2h2o) nanocrystallites. wild-type mr-1 f ...201323719584
conserved inhibitory mechanism and competent atp binding mode for adenylyltransferases with fic fold.the ubiquitous fic domain is evolutionarily conserved from bacteria to human and has been shown to catalyze amp transfer onto protein side-chain hydroxyl groups. recently, it was predicted that most catalytically competent fic proteins are inhibited by the presence of an inhibitory helix αinh that is provided by a cognate anti-toxin (class i), or is part of the n- or c-terminal part of the fic protein itself (classes ii and iii). in vitro, inhibition is relieved by mutation of a conserved glutam ...201323738009
aerotaxis governs floating biofilm formation in shewanella oneidensis.floating biofilm, or pellicle, is a biofilm found at the air-liquid interface. here, we show that pellicle development of the aquatic bacterium shewanella oneidensis is under the control of the chemotaxis system (che3), a regulatory system known to pilot planktonic cell motion according to environmental cues. deletion of the histidine kinase chea3 or the response regulator chey3 gene led to a heterogeneous pellicle or to the absence of pellicle respectively. in addition, a non-phosphorylatable c ...201323751053
the roles of outer membrane cytochromes of shewanella and geobacter in extracellular electron transfer.as key components of the electron transfer (et) pathways used for dissimilatory reduction of solid iron [fe(iii)] (hydr)oxides, outer membrane multihaem c-type cytochromes mtrc and omca of shewanella oneidensis mr-1 and omce and omcs of geobacter sulfurreducens mediate et reactions extracellularly. both mtrc and omca are at least partially exposed to the extracellular side of the outer membrane and their translocation across the outer membrane is mediated by bacterial type ii secretion system. p ...200923765850
microbial-enzymatic-hybrid biological fuel cell with optimized growth conditions for shewanella oneidensis dsp-10.in this work we present a biological fuel cell fabricated by combining a shewanella oneidensis microbial anode and a laccase-modified air-breathing cathode. this concept is devised as an extension to traditional biochemical methods by incorporating diverse biological catalysts with the aim of powering small devices. in preparing the biological fuel cell anode, novel hierarchical-structured architectures and biofilm configurations were investigated. a method for creating an artificial biofilm bas ...201323769313
oxygen consumption rates of bacteria under nutrient-limited conditions.many environments on earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. to better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. the oxygen consumption and population density of batch cultures of escherichia coli k-12, shewanella oneidensis mr-1, and marinobacter aquaeolei vt8 were tracked for up to 200 days. t ...201323770901
pdeb, a cyclic di-gmp-specific phosphodiesterase that regulates shewanella oneidensis mr-1 motility and biofilm formation.shewanella oneidensis mr-1, a gammaproteobacterium with respiratory versatility, forms biofilms on mineral surfaces through a process controlled by the cyclic dinucleotide messenger c-di-gmp. cellular concentrations of c-di-gmp are maintained by proteins containing ggdef and eal domains, which encode diguanylate cyclases for c-di-gmp synthesis and phosphodiesterases for c-di-gmp hydrolysis, respectively. the s. oneidensis mr-1 genome encodes several ggdef and eal domain proteins (50 and 31, resp ...201323794617
protein-protein interaction regulates the direction of catalysis and electron transfer in a redox enzyme complex.protein-protein interactions are well-known to regulate enzyme activity in cell signaling and metabolism. here, we show that protein-protein interactions regulate the activity of a respiratory-chain enzyme, cyma, by changing the direction or bias of catalysis. cyma, a member of the widespread napc/nirt superfamily, is a menaquinol-7 (mq-7) dehydrogenase that donates electrons to several distinct terminal reductases in the versatile respiratory network of shewanella oneidensis . we report the inc ...201323799249
promoted reduction of tellurite and formation of extracellular tellurium nanorods by concerted reaction between iron and shewanella oneidensis mr-1.the reduction of tellurite (te(iv)) by dissimilatory metal reducing bacterium, shewanella oneidensis mr-1, was promoted in the presence of fe(iii) in comparison with te(iv) bioreduction in the absence of fe(iii). electron microscopic analyses revealed that iron promoted te(iv) reduction led to form exclusively extracellular crystalline te(0) nanorods, as compared to the mostly intracellular formation of te(0) nanorods in the absence of fe(iii). the te k-edge x-ray absorption spectrometric analys ...201323802169
differential arsenic mobilization from as-bearing ferrihydrite by iron-respiring shewanella strains with different arsenic-reducing activities.arsenic immobilization and release in the environment is significantly influenced by bacterial oxidation and reduction of arsenic and arsenic-bearing minerals. in this study, we tested three iron-reducing bacteria, shewanella oneidensis mr-1, shewanella sp. hn-41, and shewanella putrefaciens 200, which have diverse arsenate-reducing activities with regard to reduction of an as-bearing ferrihydrite slurry. in the cultures of s. oneidensis mr-1 and shewanella sp. hn-41, which are not capable of re ...201323802758
fate of arsenic during microbial reduction of biogenic versus abiogenic as-fe(iii)-mineral coprecipitates.fe(iii) (oxyhydr)oxide minerals exhibit a high sorption affinity for arsenic (as) and the reductive dissolution of as-bearing fe(iii) (oxyhydr)oxides is considered to be the primary mechanism for as release into groundwater. to date, research has focused on the reactivity of abiogenic fe(iii) (oxyhydr)oxides, yet in nature biogenic fe(iii) (oxyhydr)oxides, precipitated by fe(ii)-oxidizing bacteria are also present. these biominerals contain cell-derived organic matter (cdom), leading to differen ...201323806105
structural insights into substrate recognition in proton-dependent oligopeptide transporters.short-chain peptides are transported across membranes through promiscuous proton-dependent oligopeptide transporters (pots)--a subfamily of the major facilitator superfamily (mfs). the human pots, pept1 and pept2, are also involved in the absorption of various drugs in the gut as well as transport to target cells. here, we present a structure of an oligomeric pot transporter from shewanella oneidensis (peptso2), which was crystallized in the inward open conformation in complex with the peptidomi ...201323867627
investigation of roles of divalent cations in shewanella oneidensis pellicle formation reveals unique impacts of insoluble iron.bacteria adopt a variety of lifestyles in their natural habitats and can alternate among different lifestyles in response to environmental changes. at high cell densities, bacteria can form extracellular matrix encased cell population on submerged tangible surfaces (biofilms), or at the air-liquid interface (pellicles). compared to biofilm, pellicle lifestyle allows for better oxygen access, but is metabolically more costly to maintain. further understanding of pellicle formation and environment ...201323911985
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