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  1. AU="Bhat, Swapna"
  2. AU="Christofer Lundqvist"
  3. AU="Mendez, Carol"
  4. AU="Cosimi, Anthony Benedict"
  5. AU="Rhoton, Albert L"
  6. AU="Ahmad, Ahmir"
  7. AU="Salewski, D L"
  8. AU="Akaichi, Faical"
  9. AU="Terry, C C"
  10. AU="VanMorlan, Amie M"
  11. AU="Marcus, Gail"

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  1. Artikel ; Online: Fatty acids from membrane lipids become incorporated into lipid bodies during Myxococcus xanthus differentiation.

    Bhat, Swapna / Boynton, Tye O / Pham, Dan / Shimkets, Lawrence J

    PloS one

    2014  Band 9, Heft 6, Seite(n) e99622

    Abstract: Myxococcus xanthus responds to amino acid limitation by producing fruiting bodies containing dormant spores. During development, cells produce triacylglycerides in lipid bodies that become consumed during spore maturation. As the cells are starved to ... ...

    Abstract Myxococcus xanthus responds to amino acid limitation by producing fruiting bodies containing dormant spores. During development, cells produce triacylglycerides in lipid bodies that become consumed during spore maturation. As the cells are starved to induce development, the production of triglycerides represents a counterintuitive metabolic switch. In this paper, lipid bodies were quantified in wild-type strain DK1622 and 33 developmental mutants at the cellular level by measuring the cross sectional area of the cell stained with the lipophilic dye Nile red. We provide five lines of evidence that triacylglycerides are derived from membrane phospholipids as cells shorten in length and then differentiate into myxospores. First, in wild type cells, lipid bodies appear early in development and their size increases concurrent with an 87% decline in membrane surface area. Second, developmental mutants blocked at different stages of shortening and differentiation accumulated lipid bodies proportionate with their cell length with a Pearson's correlation coefficient of 0.76. Third, peripheral rods, developing cells that do not produce lipid bodies, fail to shorten. Fourth, genes for fatty acid synthesis are down-regulated while genes for fatty acid degradation are up regulated. Finally, direct movement of fatty acids from membrane lipids in growing cells to lipid bodies in developing cells was observed by pulse labeling cells with palmitate. Recycling of lipids released by Programmed Cell Death appears not to be necessary for lipid body production as a fadL mutant was defective in fatty acid uptake but proficient in lipid body production. The lipid body regulon involves many developmental genes that are not specifically involved in fatty acid synthesis or degradation. MazF RNA interferase and its target, enhancer-binding protein Nla6, appear to negatively regulate cell shortening and TAG accumulation whereas most cell-cell signals activate these processes.
    Mesh-Begriff(e) Bacterial Proteins/genetics ; Bacterial Proteins/metabolism ; Endoribonucleases/genetics ; Endoribonucleases/metabolism ; Fatty Acids/genetics ; Fatty Acids/metabolism ; Lipid Droplets/metabolism ; Membrane Lipids/genetics ; Membrane Lipids/metabolism ; Myxococcus xanthus/physiology ; Spores, Bacterial/genetics ; Spores, Bacterial/metabolism
    Chemische Substanzen Bacterial Proteins ; Fatty Acids ; Membrane Lipids ; Endoribonucleases (EC 3.1.-)
    Sprache Englisch
    Erscheinungsdatum 2014-06-06
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0099622
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  2. Artikel: Two Lipid Signals Guide Fruiting Body Development of Myxococcus xanthus

    Bhat, Swapna / Ahrendt, Tilman / Dauth, Christina / Bode, Helge B / Shimkets, Lawrence J

    mBio. 2014 Feb. 28, v. 5, no. 1

    2014  

    Abstract: Myxococcus xanthus produces several extracellular signals that guide fruiting body morphogenesis and spore differentiation. Mutants defective in producing a signal may be rescued by codevelopment with wild-type cells or cell fractions containing the ... ...

    Abstract Myxococcus xanthus produces several extracellular signals that guide fruiting body morphogenesis and spore differentiation. Mutants defective in producing a signal may be rescued by codevelopment with wild-type cells or cell fractions containing the signal. In this paper, we identify two molecules that rescue development of the E signal-deficient mutant LS1191 at physiological concentrations, iso 15:0 branched-chain fatty acid (FA) and 1- iso 15:0-alkyl-2,3-di- iso 15:0-acyl glycerol (TG1), a development-specific monoalkyl-diacylglycerol. The physiological concentrations of the bioactive lipids were determined by mass spectrometry from developing wild-type cells using chemically synthesized standards. Synthetic TG1 restored fruiting body morphogenesis and sporulation and activated the expression of the developmentally regulated gene with locus tag MXAN_2146 at physiological concentrations, unlike its nearly identical tri- iso 15:0 triacylglycerol (TAG) counterpart, which has an ester linkage instead of an ether linkage. iso 15:0 FA restored development at physiological concentrations, unlike palmitic acid, a straight-chain fatty acid. The addition of either lipid stimulates cell shortening, with an 87% decline in membrane surface area, concomitantly with the production of lipid bodies at each cell pole and in the center of the cell. We suggest that cells produce triacylglycerol from membrane phospholipids. Bioactive lipids may be released by p rogrammed c ell d eath (PCD), which claims up to 80% of developing cells, since cells undergoing PCD produce lipid bodies before lysing. IMPORTANCE Like mammalian adipose tissue, many of the M. xanthus lipid body lipids are triacylglycerols (TAGs), containing ester-linked fatty acids. In both systems, ester-linked fatty acids are retrieved from TAGs with lipases and consumed by the fatty acid degradation cycle. Both mammals and M. xanthus also produce lipids containing ether-linked fatty alcohols with alkyl or vinyl linkages, such as plasmalogens. Alkyl and vinyl linkages are not hydrolyzed by lipases, and no clear role has emerged for lipids bearing them. For example, plasmalogen deficiency in mice has detrimental consequences to spermatocyte development, myelination, axonal survival, eye development, and long-term survival, though the precise reasons remain elusive. Lipids containing alkyl- and vinyl-linked fatty alcohols are development-specific products in M. xanthus . Here, we show that one of them rescues the development of E signal-producing mutants at physiological concentrations.
    Schlagwörter Myxococcus xanthus ; bioactive properties ; body fat ; branched chain fatty acids ; fatty alcohols ; fruiting bodies ; genes ; lipid bodies ; loci ; mass spectrometry ; morphogenesis ; mutants ; palmitic acid ; phospholipids ; spores ; sporulation ; surface area ; triacylglycerol lipase ; triacylglycerols
    Sprache Englisch
    Erscheinungsverlauf 2014-0228
    Umfang p. e00939-13.
    Erscheinungsort American Society for Microbiology
    Dokumenttyp Artikel
    ZDB-ID 2557172-2
    ISSN 2150-7511 ; 2161-2129
    ISSN (online) 2150-7511
    ISSN 2161-2129
    DOI 10.1128/mBio.00939-13
    Datenquelle NAL Katalog (AGRICOLA)

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  3. Artikel ; Online: Two lipid signals guide fruiting body development of Myxococcus xanthus.

    Bhat, Swapna / Ahrendt, Tilman / Dauth, Christina / Bode, Helge B / Shimkets, Lawrence J

    mBio

    2014  Band 5, Heft 1, Seite(n) e00939–13

    Abstract: Unlabelled: Myxococcus xanthus produces several extracellular signals that guide fruiting body morphogenesis and spore differentiation. Mutants defective in producing a signal may be rescued by codevelopment with wild-type cells or cell fractions ... ...

    Abstract Unlabelled: Myxococcus xanthus produces several extracellular signals that guide fruiting body morphogenesis and spore differentiation. Mutants defective in producing a signal may be rescued by codevelopment with wild-type cells or cell fractions containing the signal. In this paper, we identify two molecules that rescue development of the E signal-deficient mutant LS1191 at physiological concentrations, iso15:0 branched-chain fatty acid (FA) and 1-iso15:0-alkyl-2,3-di-iso15:0-acyl glycerol (TG1), a development-specific monoalkyl-diacylglycerol. The physiological concentrations of the bioactive lipids were determined by mass spectrometry from developing wild-type cells using chemically synthesized standards. Synthetic TG1 restored fruiting body morphogenesis and sporulation and activated the expression of the developmentally regulated gene with locus tag MXAN_2146 at physiological concentrations, unlike its nearly identical tri-iso15:0 triacylglycerol (TAG) counterpart, which has an ester linkage instead of an ether linkage. iso15:0 FA restored development at physiological concentrations, unlike palmitic acid, a straight-chain fatty acid. The addition of either lipid stimulates cell shortening, with an 87% decline in membrane surface area, concomitantly with the production of lipid bodies at each cell pole and in the center of the cell. We suggest that cells produce triacylglycerol from membrane phospholipids. Bioactive lipids may be released by programmed cell death (PCD), which claims up to 80% of developing cells, since cells undergoing PCD produce lipid bodies before lysing.
    Importance: Like mammalian adipose tissue, many of the M. xanthus lipid body lipids are triacylglycerols (TAGs), containing ester-linked fatty acids. In both systems, ester-linked fatty acids are retrieved from TAGs with lipases and consumed by the fatty acid degradation cycle. Both mammals and M. xanthus also produce lipids containing ether-linked fatty alcohols with alkyl or vinyl linkages, such as plasmalogens. Alkyl and vinyl linkages are not hydrolyzed by lipases, and no clear role has emerged for lipids bearing them. For example, plasmalogen deficiency in mice has detrimental consequences to spermatocyte development, myelination, axonal survival, eye development, and long-term survival, though the precise reasons remain elusive. Lipids containing alkyl- and vinyl-linked fatty alcohols are development-specific products in M. xanthus. Here, we show that one of them rescues the development of E signal-producing mutants at physiological concentrations.
    Mesh-Begriff(e) Lipid Metabolism ; Lipids/chemistry ; Lipids/isolation & purification ; Mass Spectrometry ; Myxococcus xanthus/growth & development ; Signal Transduction ; Spores, Bacterial/growth & development
    Chemische Substanzen Lipids
    Sprache Englisch
    Erscheinungsdatum 2014-02-11
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2557172-2
    ISSN 2150-7511 ; 2161-2129
    ISSN (online) 2150-7511
    ISSN 2161-2129
    DOI 10.1128/mBio.00939-13
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  4. Artikel ; Online: Genome evolution and the emergence of fruiting body development in Myxococcus xanthus.

    Goldman, Barry / Bhat, Swapna / Shimkets, Lawrence J

    PloS one

    2007  Band 2, Heft 12, Seite(n) e1329

    Abstract: Background: Lateral gene transfer (LGT) is thought to promote speciation in bacteria, though well-defined examples have not been put forward.: Methodology/principle findings: We examined the evolutionary history of the genes essential for a trait ... ...

    Abstract Background: Lateral gene transfer (LGT) is thought to promote speciation in bacteria, though well-defined examples have not been put forward.
    Methodology/principle findings: We examined the evolutionary history of the genes essential for a trait that defines a phylogenetic order, namely fruiting body development of the Myxococcales. Seventy-eight genes that are essential for Myxococcus xanthus development were examined for LGT. About 73% of the genes exhibit a phylogeny similar to that of the 16S rDNA gene and a codon bias consistent with other M. xanthus genes suggesting vertical transmission. About 22% have an altered codon bias and/or phylogeny suggestive of LGT. The remaining 5% are unique. Genes encoding signal production and sensory transduction were more likely to be transmitted vertically with clear examples of duplication and divergence into multigene families. Genes encoding metabolic enzymes were frequently acquired by LGT. Myxobacteria exhibit aerobic respiration unlike most of the delta Proteobacteria. M. xanthus contains a unique electron transport pathway shaped by LGT of genes for succinate dehydrogenase and three cytochrome oxidase complexes.
    Conclusions/significance: Fruiting body development depends on genes acquired by LGT, particularly those involved in polysaccharide production. We suggest that aerobic growth fostered innovation necessary for development by allowing myxobacteria access to a different gene pool from anaerobic members of the delta Proteobacteria. Habitat destruction and loss of species diversity could restrict the evolution of new bacterial groups by limiting the size of the prospective gene pool.
    Mesh-Begriff(e) Biological Evolution ; Gene Transfer, Horizontal ; Genes, Bacterial ; Genes, Essential ; Genome, Bacterial ; Myxococcus xanthus/genetics ; Myxococcus xanthus/growth & development ; Myxococcus xanthus/metabolism ; Oxygen/metabolism
    Chemische Substanzen Oxygen (S88TT14065)
    Sprache Englisch
    Erscheinungsdatum 2007-12-26
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0001329
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  5. Artikel ; Online: Identification and localization of Myxococcus xanthus porins and lipoproteins.

    Bhat, Swapna / Zhu, Xiang / Patel, Ricky P / Orlando, Ron / Shimkets, Lawrence J

    PloS one

    2011  Band 6, Heft 11, Seite(n) e27475

    Abstract: Myxococcus xanthus DK1622 contains inner (IM) and outer membranes (OM) separated by a peptidoglycan layer. Integral membrane, β-barrel proteins are found exclusively in the OM where they form pores allowing the passage of nutrients, waste products and ... ...

    Abstract Myxococcus xanthus DK1622 contains inner (IM) and outer membranes (OM) separated by a peptidoglycan layer. Integral membrane, β-barrel proteins are found exclusively in the OM where they form pores allowing the passage of nutrients, waste products and signals. One porin, Oar, is required for intercellular communication of the C-signal. An oar mutant produces CsgA but is unable to ripple or stimulate csgA mutants to develop suggesting that it is the channel for C-signaling. Six prediction programs were evaluated for their ability to identify β-barrel proteins. No program was reliable unless the predicted proteins were first parsed using Signal P, Lipo P and TMHMM, after which TMBETA-SVM and TMBETADISC-RBF identified β-barrel proteins most accurately. 228 β-barrel proteins were predicted from among 7331 protein coding regions, representing 3.1% of total genes. Sucrose density gradients were used to separate vegetative cell IM and OM fractions, and LC-MS/MS of OM proteins identified 54 β-barrel proteins. Another class of membrane proteins, the lipoproteins, are anchored in the membrane via a lipid moiety at the N-terminus. 44 OM proteins identified by LC-MS/MS were predicted lipoproteins. Lipoproteins are distributed between the IM, OM and ECM according to an N-terminal sorting sequence that varies among species. Sequence analysis revealed conservation of alanine at the +7 position of mature ECM lipoproteins, lysine at the +2 position of IM lipoproteins, and no noticable conservation within the OM lipoproteins. Site directed mutagenesis and immuno transmission electron microscopy showed that alanine at the +7 position is essential for sorting of the lipoprotein FibA into the ECM. FibA appears at normal levels in the ECM even when a +2 lysine is added to the signal sequence. These results suggest that ECM proteins have a unique method of secretion. It is now possible to target lipoproteins to specific IM, OM and ECM locations by manipulating the amino acid sequence near the +1 cysteine processing site.
    Mesh-Begriff(e) Amino Acid Sequence ; Bacterial Outer Membrane Proteins/chemistry ; Bacterial Outer Membrane Proteins/isolation & purification ; Bacterial Proteins/chemistry ; Bacterial Proteins/metabolism ; Chromatography, Liquid ; Computational Biology ; Databases, Protein ; Extracellular Matrix Proteins/metabolism ; Lipoproteins/chemistry ; Lipoproteins/metabolism ; Mass Spectrometry ; Molecular Sequence Data ; Myxococcus xanthus/metabolism ; Myxococcus xanthus/ultrastructure ; Porins/chemistry ; Porins/metabolism ; Protein Sorting Signals ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein Transport ; Proteome/metabolism ; Signal Transduction
    Chemische Substanzen Bacterial Outer Membrane Proteins ; Bacterial Proteins ; Extracellular Matrix Proteins ; Lipoproteins ; Porins ; Protein Sorting Signals ; Proteome
    Sprache Englisch
    Erscheinungsdatum 2011-11-22
    Erscheinungsland United States
    Dokumenttyp Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0027475
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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  6. Artikel ; Online: Survival in nuclear waste, extreme resistance, and potential applications gleaned from the genome sequence of Kineococcus radiotolerans SRS30216.

    Bagwell, Christopher E / Bhat, Swapna / Hawkins, Gary M / Smith, Bryan W / Biswas, Tapan / Hoover, Timothy R / Saunders, Elizabeth / Han, Cliff S / Tsodikov, Oleg V / Shimkets, Lawrence J

    PloS one

    2008  Band 3, Heft 12, Seite(n) e3878

    Abstract: Kineococcus radiotolerans SRS30216 was isolated from a high-level radioactive environment at the Savannah River Site (SRS) and exhibits gamma-radiation resistance approaching that of Deinococcus radiodurans. The genome was sequenced by the U.S. ... ...

    Abstract Kineococcus radiotolerans SRS30216 was isolated from a high-level radioactive environment at the Savannah River Site (SRS) and exhibits gamma-radiation resistance approaching that of Deinococcus radiodurans. The genome was sequenced by the U.S. Department of Energy's Joint Genome Institute which suggested the existence of three replicons, a 4.76 Mb linear chromosome, a 0.18 Mb linear plasmid, and a 12.92 Kb circular plasmid. Southern hybridization confirmed that the chromosome is linear. The K. radiotolerans genome sequence was examined to learn about the physiology of the organism with regard to ionizing radiation resistance, the potential for bioremediation of nuclear waste, and the dimorphic life cycle. K. radiotolerans may have a unique genetic toolbox for radiation protection as it lacks many of the genes known to confer radiation resistance in D. radiodurans. Additionally, genes involved in the detoxification of reactive oxygen species and the excision repair pathway are overrepresented. K. radiotolerans appears to lack degradation pathways for pervasive soil and groundwater pollutants. However, it can respire on two organic acids found in SRS high-level nuclear waste, formate and oxalate, which promote the survival of cells during prolonged periods of starvation. The dimorphic life cycle involves the production of motile zoospores. The flagellar biosynthesis genes are located on a motility island, though its regulation could not be fully discerned. These results highlight the remarkable ability of K radiotolerans to withstand environmental extremes and suggest that in situ bioremediation of organic complexants from high level radioactive waste may be feasible.
    Mesh-Begriff(e) Actinomycetales/genetics ; Actinomycetales/metabolism ; Actinomycetales/radiation effects ; Biodegradation, Environmental ; Chemotaxis ; Genes, Bacterial ; Genome, Bacterial ; Radiation Tolerance/genetics ; Radiation, Ionizing ; Radioactive Waste ; Reactive Oxygen Species
    Chemische Substanzen Radioactive Waste ; Reactive Oxygen Species
    Sprache Englisch
    Erscheinungsdatum 2008-12-05
    Erscheinungsland United States
    Dokumenttyp Comparative Study ; Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0003878
    Datenquelle MEDical Literature Analysis and Retrieval System OnLINE

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