Significance of β-sheet formation for micellization and surface adsorption of surfactin

Ishigami, Yutaka; Osman, Mohamad; Nakahara, Hisae; Sano, Yoh; Ishiguro, R.; Matsumoto, Mutsuo

doi:10.1016/0927-7765(94)01183-6

Cited by 127 publications

(136 citation statements)

References 18 publications

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“…It contains ß-hydroxy fatty acids with side chains of 13-15 carbon atoms. Due to its amphiphilic structure it shows unique surface-, interface-and membrane-active properties [1,2,[8][9][10][11][12]] and a strong tendency for self-aggregation forming micelles and vesicles [13,14].…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-α-dimyristoyl phosphatidylcholine

Kell

Holzwarth

Boettcher

et al. 2007

Biophysical Chemistry

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ochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of L-α-dimyristoyl phosphatidylcholine. Biophysical Chemistry, Elsevier, 2007, 128 (2-3) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D

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Section: Accepted M Manuscriptmentioning

confidence: 99%

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-α-dimyristoyl phosphatidylcholine

Kell

Holzwarth

Boettcher

et al. 2007

Biophysical Chemistry

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“…Phosphorylated ComA directly modulates the expression of various genes, including the srfA operon (6, 11) needed for nonribosomal synthesis of the major lipopeptide antibiotic surfactin (12). Surfactin is also one of the most effective biosurfactants discovered so far (13)(14)(15); it can penetrate cell membranes of various bacteria (16), inhibit surface adhesion of different pathogens, and act as an antiviral (17,18) or hemolytic agent (18). As surfactin is secreted and affects nonsecretors (19), it can be considered a public good (3,4).…”

mentioning

confidence: 99%

Private link between signal and response in Bacillus subtilis quorum sensing

Oslizlo

Štefanič

Dogša

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Bacteria coordinate their behavior using quorum sensing (QS), whereby cells secrete diffusible signals that generate phenotypic responses associated with group living. The canonical model of QS is one of extracellular signaling, where signal molecules bind to cognate receptors and cause a coordinated response across many cells. Here we study the link between QS input (signaling) and QS output (response) in the ComQXPA QS system of Bacillus subtilis by characterizing the phenotype and fitness of comQ null mutants. These lack the enzyme to produce the ComX signal and do not activate the ComQXPA QS system in other cells. In addition to the activation effect of the signal, however, we find evidence of a second, repressive effect of signal production on the QS system. Unlike activation, which can affect other cells, repression acts privately: the de-repression of QS in comQ cells is intracellular and only affects mutant cells lacking ComQ. As a result, the QS signal mutants have an overly responsive QS system and overproduce the secondary metabolite surfactin in the presence of the signal. This surfactin overproduction is associated with a strong fitness cost, as resources are diverted away from primary metabolism. Therefore, by acting as a private QS repressor, ComQ may be protected against evolutionary competition from loss-of-function mutations. Additionally, we find that surfactin participates in a social selection mechanism that targets signal null mutants in coculture with signal producers. Our study shows that by pleiotropically combining intracellular and extracellular signaling, bacteria may generate evolutionarily stable QS systems.social interactions | social evolution B acteria secrete and share quorum-sensing (QS) signaling molecules that bind to specific receptors, and upon reaching critical concentration induce cell density-dependent adaptive responses within the population (1). In Gram-positive bacteria small peptide QS signals are typically produced from oligopeptide precursors that are modified by a signal-processing enzyme before they are secreted from the cell. It is assumed that these bacteria secrete QS signals during growth, and then in the stationary phase when the signal threshold concentration is reached, the signals activate specific histidine kinase receptors. These activate specific response regulators through phosphotransfer, which then initiate a QS response (2). The QS response often involves expression of adaptive extracellular factors (such as food-degrading enzymes, virulence factors, antibiotics, or biosurfactants) that are considered public goods (3, 4), as they can be shared within the population. Recently, however, it was shown that the QS of Gramnegative bacteria may also regulate adaptive metabolic pathways that produce molecules that remain private as they are not secreted by the responsive cells (5).The ComQXPA QS system of Bacillus subtilis is a typical QS system of Gram-positive bacteria that controls expression of nearly 200 genes, including both extracellular and private...

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“…Surfactin, which adopts a characteristic horse-saddle conformation in water [34,35] is an amphiphilic lipopeptide produced by various strains of Bacillus subtilis. It consists of a heptapeptide head-group, linked to a C 12 -C 15 ␤-hydroxy fatty acid.…”

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confidence: 99%

Enhanced ion signals in desorption electrospray ionization using surfactant spray solutions

Badu‐Tawiah

Cooks

2010

J. Am. Soc. Mass Spectrom.

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Solvent optimization is an important procedure in desorption electrospray ionization (DESI) and in this study the effects of solvent surface tension are explored. Data are presented for methanol/water/surfactant solvent systems, which show increases in ion signals of more than an order of magnitude when low concentrations of surfactants are added to the standard methanol/water (1:1) spray solvent. Examples of analytes tested include food chemicals, peptides, pharmaceuticals, and drugs of abuse. The improvement in ion intensity is mainly attributed to the effect of surface tension in producing smaller spray droplets, which are shown to cover a larger surface area. Surfactant-containing spray solutions allowed extension of DESI-MS analysis to previously intractable analytes like melamine and highly hydrophobic compounds like the sudan dyes. ( [3][4][5][6][7][8], which is used for surface sampling [9,10], high throughput analysis [11,12], and chemical imaging [13][14][15][16][17], largely because of its applicability to in situ analyte detection from unmodified surfaces. In DESI, a nebulized electrospray of high-velocity charged microdroplets is directed at a surface from which the solvent extracts analyte and carries it to the mass spectrometer in the form of secondary microdroplets. This methodology has been applied in a variety of disciplines including forensics [18,19], environmental science [20], food science [12,21], and pharmaceutical science [22]. With increased interest in ambient desorption mass spectrometry, the need has arisen to develop more versatile solvent systems that are applicable to a wider range of samples than is currently the case. One aspect of this effort is the use of non-aqueous spray solutions [23] and another is the addition of reagents to the spray solvent chosen to react and give ionic derivatives of the analytes of interest [24]. Both are discussed further below. In this work, we explore the special properties of spray solutions containing surfactants, in an attempt to increase the ion intensity and to learn more about the mechanisms of DESI.Three mechanisms have been identified in DESI, all falling under the rubric of droplet pick-up. The first and best established is the droplet micro-extraction mechanism [25,26]. In this mechanism, initial droplets arriving at the surface form a localized and probably discontinuous liquid thin film, which dissolves analyte present on the surface. Subsequent droplet-liquid-thin-film collisions produce secondary microdroplets containing the analyte, which are then sucked into the mass spectrometer for mass/charge analysis. A second mechanism is believed to involve gas-phase ion/molecule reactions [2]. In this case, vaporization of the analyte from the surface is followed by fast charge-transfer reactions with protonated (or other) solvent molecules or droplets to produce charged analytes, which are then transferred into the mass spectrometer for mass analysis. A third mechanism, which also seems to make a limited contribution to ion production in ...

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Significance of β-sheet formation for micellization and surface adsorption of surfactin

Cited by 127 publications

References 18 publications

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-α-dimyristoyl phosphatidylcholine

Physicochemical studies of the interaction of the lipoheptapeptide surfactin with lipid bilayers of l-α-dimyristoyl phosphatidylcholine

Private link between signal and response in Bacillus subtilis quorum sensing

Enhanced ion signals in desorption electrospray ionization using surfactant spray solutions

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