RESUMEN
Sestrins are stress-inducible metabolic regulators with two seemingly unrelated but physiologically important functions: reduction of reactive oxygen species (ROS) and inhibition of the mechanistic target of rapamycin complex 1 (mTORC1). How Sestrins fulfil this dual role has remained elusive so far. Here we report the crystal structure of human Sestrin2 (hSesn2), and show that hSesn2 is twofold pseudo-symmetric with two globular subdomains, which are structurally similar but functionally distinct from each other. While the N-terminal domain (Sesn-A) reduces alkylhydroperoxide radicals through its helix-turn-helix oxidoreductase motif, the C-terminal domain (Sesn-C) modified this motif to accommodate physical interaction with GATOR2 and subsequent inhibition of mTORC1. These findings clarify the molecular mechanism of how Sestrins can attenuate degenerative processes such as aging and diabetes by acting as a simultaneous inhibitor of ROS accumulation and mTORC1 activation.
Asunto(s)
Complejos Multiproteicos/metabolismo , Proteínas Nucleares/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Línea Celular Tumoral , Cromatografía en Gel , Cristalización , Escherichia coli , Células HEK293 , Secuencias Hélice-Giro-Hélice , Humanos , Immunoblotting , Inmunoprecipitación , Técnicas In Vitro , Diana Mecanicista del Complejo 1 de la Rapamicina , Proteínas Nucleares/química , Oxidorreductasas/metabolismo , Estructura Terciaria de Proteína , Transducción de SeñalRESUMEN
A series of structurally-related [Cu(R-benzyl-dipicolylamine)(NO3)2] complexes, where R=methoxy- (1), methyl- (2), H- (3), fluoro- (4), and nitro-group (5), were synthesized, and their activity on DNA cleavage was investigated by linear dichroism (LD) and electrophoresis. The addition of a benzyl group to the dipicolylamine ligand of the [Cu(dipicolylamine)(NO3)2] complex (A), i.e., the [Cu(benzyl-dipicolylamine)(NO3)2] complex (3), caused significant enhancement in the efficiency of oxidative cleavage of both super-coiled (sc) and double stranded (ds) DNA, as evidenced by the electrophoresis pattern and faster decrease in the LD intensity at 260nm. The efficiency in DNA cleavage was also altered with further modifications of the benzyl group by the introduction of various substituents at the para-position. The cleavage efficiency appeared to be the largest when the methyl group was attached. The order of efficiency in DNA cleavage was methyl>methoxy≈H>fluoro≈nitro group. When an electron-withdrawing group was introduced, the cleavage efficiency decreased remarkably. The reactive oxygen species involved in the cleavage process were the superoxide radical and singlet oxygen. A possible mechanism for this variation in the DNA cleavage efficiency was proposed.
Asunto(s)
Complejos de Coordinación/química , Cobre/química , División del ADN , ADN Superhelicoidal/química , Sal Disódica del Ácido 1,2-Dihidroxibenceno-3,5-Disulfónico/química , Catalasa/química , Complejos de Coordinación/síntesis química , Dimetilsulfóxido/química , Depuradores de Radicales Libres/química , Oxidación-Reducción , Plásmidos , Azida Sódica/químicaRESUMEN
A new highly selective colorimetric chemosensor 1 (E)-9-(((5-mercapto-1,3,4-thiadiazol-2-yl)imino)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol was designed and synthesized for the sequential detection of Cu(2+) and CN(-). This sensor 1 exhibited an obvious color change from yellow to orange in the presence of Cu(2+) in a fully aqueous solution. The detection limit (0.9 µM) of 1 for Cu(2+) is far lower than the WHO limit (31.5 µM) for drinking water. In addition, the resulting Cu(2+)-2· 1 complex can be further used to detect toxic cyanide through a color change from orange to yellow, indicating the recovery of 1 from Cu(2+)-2·1. Importantly, chemosensor 1 could be used to detect and quantify Cu(2+) in water samples, and a colorimetric test strip of 1 for the detection of Cu(2+) could be useful for all practical purposes.
Asunto(s)
Colorimetría , Colorantes/química , Cobre/análisis , Cianuros/análisis , Oxiquinolina/química , Piridinas/química , Colorimetría/instrumentación , Colorantes/síntesis química , Estructura Molecular , Oxiquinolina/síntesis química , Piridinas/síntesis química , Agua/químicaRESUMEN
A new simple 'naked eye' chemosensor 1 (sodium (E)-2-((2-(3-hydroxy-2-naphthoyl)hydrazono)methyl)benzoate) has been synthesized for detection of CN- in a mixture of DMF/H2O (9:1). The sensor 1 comprises of a naphthoic hydrazide as efficient hydrogen bonding donor group and a benzoic acid as the moiety with the water solubility. The receptor 1 showed high selectivity toward cyanide ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to yellow for CN- over other anions. Therefore, receptor 1 could be useful for cyanide detection in aqueous environment, displaying a high distinguishable selectivity from hydrogen bonded anions and being clearly visible to the naked eye.
Asunto(s)
Ácidos Carboxílicos/química , Colorimetría/métodos , Cianuros/química , Aniones , Cianuros/síntesis química , Soluciones , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría UltravioletaRESUMEN
A new, highly selective and sensitive colorimetric chemosensor 1 for detection of Cu(2+) ions in aqueous solution was developed. Receptor 1 detected Cu(2+) ions by changing its color from colorless to yellow. Moreover, the Cu(2+)-sensitive compound was used as a colorimetric pH detector based on a color change due to 1-Cu(2+) complex formation identifiable by the naked eye.
Asunto(s)
Colorimetría/métodos , Cobre/análisis , Furanos/síntesis química , Guanidinas/síntesis química , Contaminantes Químicos del Agua/análisis , Furanos/química , Guanidinas/química , Espectroscopía de Resonancia Magnética , Estructura Molecular , Espectrometría de Masa por Ionización de Electrospray , Espectrofotometría Infrarroja , Espectrofotometría UltravioletaRESUMEN
A new highly selective and sensitive colorimetric chemosensor 1 for Co(2+) was developed. The receptor 1 sensed Co(2+) by changing its color from yellow to orange in aqueous solution. Moreover, 1 could be used as a practical, visible colorimetric test kit for Co(2+).
Asunto(s)
Cobalto/análisis , Colorantes Fluorescentes/química , Agua/análisis , Colorimetría/métodos , Espectrofotometría Ultravioleta/métodosRESUMEN
A new metal ion sensor that contains quinoline and pyridylaminophenol has been synthesized. In acetonitrile and in the presence of Zn(2+), the sensor fluoresces. In contrast, in aqueous solutions the sensor fluoresces in the presence of Cd(2+). The fluorescence of the molecule is selective for Zn(2+) or Cd(2+) and shows no fluorescence with other metal ions. The crystal structure of the Cd(2+) complex shows coordination through the amide and phenol oxygens, as well as the amine nitrogen of the sensor. The sensor also acts as a colorimetric sensor for Co(2+) by changing color from colorless to yellow. The color change is selective for Co(2+) and is not observed with other metal ions. The unique combination of pyridine and phenol groups with quinoline results in the properties of this sensor.