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1.
Chemistry ; 19(18): 5595-601, 2013 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-23463681

RESUMEN

We have developed a new benign means of reversibly breaking emulsions and latexes by using "switchable water", an aqueous solution of switchable ionic strength. The conventional surfactant sodium dodecyl sulfate (SDS) is not normally stimuli-responsive when CO2 is used as the stimulus but becomes CO2 -responsive or "switchable" in the presence of a switchable water additive. In particular, changes in the air/water surface tension and oil/water interfacial tension can be triggered by addition and removal of CO2 . A switchable water additive, N,N-dimethylethanolamine (DMEA), was found to be an effective and efficient additive for the reversible reduction of interfacial tension and can lower the tension of the dodecane/water interface in the presence of SDS surfactant to ultra-low values at very low additive concentrations. Switchable water was successfully used to reversibly break an emulsion containing SDS as surfactant, and dodecane as organic liquid. Also, the addition of CO2 and switchable water can result in aggregation of polystyrene (PS) latexes; the later removal of CO2 neutralizes the DMEA and decreases the ionic strength allowing for the aggregated PS latex to be redispersed and recovered in its original state.

2.
Mol Biol Cell ; 17(3): 1306-21, 2006 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-16394103

RESUMEN

We have used comprehensive synthetic lethal screens and biochemical assays to examine the biological role of the yeast amphiphysin homologues Rvs161p and Rvs167p, two proteins that play a role in regulation of the actin cytoskeleton, endocytosis, and sporulation. We found that unlike some forms of amphiphysin, Rvs161p-Rvs167p acts as an obligate heterodimer during vegetative growth and neither Rvs161p nor Rvs167p forms a homodimer in vivo. RVS161 and RVS167 have an identical set of 49 synthetic lethal interactions, revealing functions for the Rvs proteins in cell polarity, cell wall synthesis, and vesicle trafficking as well as a shared role in mating. Consistent with these roles, we show that the Rvs167p-Rvs161p heterodimer, like its amphiphysin homologues, can bind to phospholipid membranes in vitro, suggesting a role in vesicle formation and/or fusion. Our genetic screens also reveal that the interaction between Abp1p and the Rvs167p Src homology 3 (SH3) domain may be important under certain conditions, providing the first genetic evidence for a role for the SH3 domain of Rvs167p. Our studies implicate heterodimerization of amphiphysin family proteins in various functions related to cell polarity, cell integrity, and vesicle trafficking during vegetative growth and the mating response.


Asunto(s)
Proteínas del Citoesqueleto/química , Proteínas del Citoesqueleto/metabolismo , Proteínas del Tejido Nervioso/química , Proteínas del Tejido Nervioso/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Actinas/metabolismo , Animales , Proteínas Portadoras/metabolismo , Bovinos , Línea Celular , Membrana Celular/metabolismo , Quitina/metabolismo , Dimerización , Diploidia , Eliminación de Gen , Genes del Tipo Sexual de los Hongos , Prueba de Complementación Genética , Insectos , Proteínas de Microfilamentos , Feromonas/farmacología , Unión Proteica , Estructura Cuaternaria de Proteína , Saccharomyces cerevisiae/citología , Saccharomyces cerevisiae/efectos de los fármacos , Termodinámica , Dominios Homologos src
3.
Science ; 303(5659): 808-13, 2004 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-14764870

RESUMEN

A genetic interaction network containing approximately 1000 genes and approximately 4000 interactions was mapped by crossing mutations in 132 different query genes into a set of approximately 4700 viable gene yeast deletion mutants and scoring the double mutant progeny for fitness defects. Network connectivity was predictive of function because interactions often occurred among functionally related genes, and similar patterns of interactions tended to identify components of the same pathway. The genetic network exhibited dense local neighborhoods; therefore, the position of a gene on a partially mapped network is predictive of other genetic interactions. Because digenic interactions are common in yeast, similar networks may underlie the complex genetics associated with inherited phenotypes in other organisms.


Asunto(s)
Genes Fúngicos , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Secuencia de Aminoácidos , Biología Computacional , Fibrosis Quística/genética , Eliminación de Gen , Genes Esenciales , Enfermedades Genéticas Congénitas/genética , Genotipo , Humanos , Datos de Secuencia Molecular , Herencia Multifactorial , Mutación , Fenotipo , Polimorfismo Genético , Retinitis Pigmentosa/genética , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética
4.
J Cell Biol ; 159(6): 993-1004, 2002 Dec 23.
Artículo en Inglés | MEDLINE | ID: mdl-12499356

RESUMEN

Mechanisms for activating the actin-related protein 2/3 (Arp2/3) complex have been the focus of many recent studies. Here, we identify a novel mode of Arp2/3 complex regulation mediated by the highly conserved actin binding protein coronin. Yeast coronin (Crn1) physically associates with the Arp2/3 complex and inhibits WA- and Abp1-activated actin nucleation in vitro. The inhibition occurs specifically in the absence of preformed actin filaments, suggesting that Crn1 may restrict Arp2/3 complex activity to the sides of filaments. The inhibitory activity of Crn1 resides in its coiled coil domain. Localization of Crn1 to actin patches in vivo and association of Crn1 with the Arp2/3 complex also require its coiled coil domain. Genetic studies provide in vivo evidence for these interactions and activities. Overexpression of CRN1 causes growth arrest and redistribution of Arp2 and Crn1p into aberrant actin loops. These defects are suppressed by deletion of the Crn1 coiled coil domain and by arc35-26, an allele of the p35 subunit of the Arp2/3 complex. Further in vivo evidence that coronin regulates the Arp2/3 complex comes from the observation that crn1 and arp2 mutants display an allele-specific synthetic interaction. This work identifies a new form of regulation of the Arp2/3 complex and an important cellular function for coronin.


Asunto(s)
4-Butirolactona/análogos & derivados , 4-Butirolactona/metabolismo , Actinas/metabolismo , Proteínas del Citoesqueleto/metabolismo , Proteína 2 Relacionada con la Actina , Proteína 3 Relacionada con la Actina , Actinas/química , Alelos , Núcleo Celular/metabolismo , Centrifugación por Gradiente de Densidad , Eliminación de Gen , Regulación Fúngica de la Expresión Génica , Prueba de Complementación Genética , Immunoblotting , Cinética , Microscopía Fluorescente , Mutación , Plásmidos/metabolismo , Pruebas de Precipitina , Unión Proteica , Estructura Terciaria de Proteína , Saccharomyces cerevisiae/metabolismo , Sacarosa/farmacología , Temperatura , Factores de Tiempo , Técnicas del Sistema de Dos Híbridos
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