{"id":53293,"date":"2018-03-09T22:40:57","date_gmt":"2018-03-09T22:40:57","guid":{"rendered":"https:\/\/www.deberes.net\/tesis\/sin-categoria\/implicaciones-de-la-ndp-reductasa-en-la-progresion-de-las-horquillas-de-replicacion-en-escherichia-coli\/"},"modified":"2018-03-09T22:40:57","modified_gmt":"2018-03-09T22:40:57","slug":"implicaciones-de-la-ndp-reductasa-en-la-progresion-de-las-horquillas-de-replicacion-en-escherichia-coli","status":"publish","type":"post","link":"https:\/\/www.deberes.net\/tesis\/bioquimica\/implicaciones-de-la-ndp-reductasa-en-la-progresion-de-las-horquillas-de-replicacion-en-escherichia-coli\/","title":{"rendered":"Implicaciones de la ndp reductasa en la progresi\u00f3n de las horquillas de replicaci\u00f3n en escherichia coli"},"content":{"rendered":"<h2>Tesis doctoral de <strong> Estrella Guarino Almeida <\/strong><\/h2>\n<p>En escherichia coli, la reducci\u00f3n de los ribonucle\u00f3tidos utilizados en la s\u00edntesis de dan a sus de soxiribonucle\u00f3tidos (dntps) correspondientes se lleva a cabo por la ribonucle\u00f3tido difosfato reductasas (ndpreductasa) que es esencial para la replicaci\u00f3n del cromosoma. La mutaci\u00f3n nrda101 da lugar a una ndpreductasa termosensible. La incubaci\u00f3n a 42\u00c2\u00bac de extractos crudos o preparaciones puras de la enzima mutante destruye  su actividad en dos minutos; sin embargo, al incubar a 42\u00c2\u00bac una bacteria mutante termosensible nrda101, no se detiene la replicaci\u00f3n hasta transcurridos 40-50 minutos despu\u00e9s del cambio de temperatura. Esto sugiere que la ndp reductasa mutada podr\u00eda estar protegida de la inactivaci\u00f3n t\u00e9rmica por alguna hiperestructura, ya que el fenotipo de esta estirpe no es el caracter\u00edstico de un mutante de elongaci\u00f3n.     en este trabajo se ha analizado la progresi\u00f3n de las horquillas de reclinaci\u00f3n en una estirpe nrda101, observ\u00e1ndose que en este mutante las horquillas de replicaci\u00f3n sufren m\u00e1s paradas que en una estirpe isog\u00e9nica silvestre para el elelo nrda. Adem\u00e1s, este aumento de horquillas paradas no se debe a un menor suministro de nucle\u00f3tidos generado por un actividad parcial de la enzima mutada incluso a temperatura permisiva y las horquillas detenidas se reanudan mediante reversiones (siguiendo el modelo del rfr), al igual que ocurre al detener  la replicaci\u00f3n alterando enzimas que forman parte del replisoma. Tambi\u00e9n se ha demostrado que la s\u00edntesis residual de dna que se produce al incubar el mutante a 42\u00c2\u00bac procede sin necesidad de la acci\u00f3n de enzimas de recriminaci\u00f3n ni de la prote\u00edna pria, se\u00f1alando que durante el tiempo que la ndp reductasa permanece protegida no se produce un desensamblaje de la maquinaria de replicaci\u00f3n. Se detect\u00f3 tambi\u00e9n que la capacidad de sufrir una reversi\u00f3n de las horquillas paradas en el mutante nrda101 variada dependiendo de la estrategia empleada para inactivar la ndp reductasa -i<\/p>\n<p>&nbsp;<\/p>\n<h3>Datos acad\u00e9micos de la tesis doctoral \u00ab<strong>Implicaciones de la ndp reductasa en la progresi\u00f3n de las horquillas de replicaci\u00f3n en escherichia coli<\/strong>\u00ab<\/h3>\n<ul>\n<li><strong>T\u00edtulo de la tesis:<\/strong>\u00a0 Implicaciones de la ndp reductasa en la progresi\u00f3n de las horquillas de replicaci\u00f3n en escherichia coli <\/li>\n<li><strong>Autor:<\/strong>\u00a0 Estrella Guarino Almeida <\/li>\n<li><strong>Universidad:<\/strong>\u00a0 Extremadura<\/li>\n<li><strong>Fecha de lectura de la tesis:<\/strong>\u00a0 21\/06\/2006<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h3>Direcci\u00f3n y tribunal<\/h3>\n<ul>\n<li><strong>Director de la tesis<\/strong>\n<ul>\n<li>Alfonso Jim\u00e9nez S\u00e1nchez<\/li>\n<\/ul>\n<\/li>\n<li><strong>Tribunal<\/strong>\n<ul>\n<li>Presidente del tribunal: josep Casadesus pursals <\/li>\n<li>Ana Mar\u00eda Mata dur\u00e1n (vocal)<\/li>\n<li>Jos\u00e9 Emilio Rebollo feria (vocal)<\/li>\n<li>Jaime Correa bordes (vocal)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Tesis doctoral de Estrella Guarino Almeida En escherichia coli, la reducci\u00f3n de los ribonucle\u00f3tidos utilizados en la s\u00edntesis de dan [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center 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