Reduzierte Polyketide

Polyketide sind eine strukturell heterogene Gruppe von Naturstoffen mit oftmals faszinierenden Bioaktivitäten die therapeutisch genutzt werden können. Die für den Einsatz in der Medizin meist notwendige Derivatisierung dieser Substanzen stellt große Herausforderungen an die modernen chemischen Wissenschaften. Der Schwerpunkt dieser Dissertation liegt auf der Erforschung und Manipluation der Substratspezifität von Typ-I-Polyketidsynthasen, den zentralen und sehr komplexen Enzymen aus der Polyketid-Biosynthese. Neben klassischen Ansatzpunkten konnte die zielgerichtete Mutation von Acyltransferasen sowie der reduktiven Domänen etabliert werden. Hierdurch gelang es, sowohl neue Erkenntnisse über die Substratspezifität der Polyketidsynthasen zu gewinnen als auch neue antibiotisch wirksame Polyketid-Derivate zu erzeugen

Substrate Flexibility of a Mutated Acyltransferase Domain and Implications for Polyketide Biosynthesis

SummaryPolyketides are natural products frequently used for the treatment of various diseases, but their structural complexity hinders efficient derivatization. In this context, we recently introduced enzyme-directed mutasynthesis to incorporate non-native extender units into the biosynthesis of erythromycin. Modeling and mutagenesis studies led to the discovery of a variant of an acyltransferase domain in the erythromycin polyketide synthase capable of accepting a propargylated substrate. Here, we extend molecular rationalization of enzyme-substrate interactions through modeling, to investigate the incorporation of substrates with different degrees of saturation of the malonic acid side chain. This allowed the engineered biosynthesis of new erythromycin derivatives and the introduction of additional mutations into the AT domain for a further shift of the enzyme's substrate scope. Our approach yields non-native polyketide structures with functional groups that will simplify future derivatization approaches, and provides a blueprint for the engineering of AT domains to achieve efficient polyketide synthase diversification

Die Entwicklung der DNA-Sequenzierung : vom Genom eines Bakteriophagen zum Neandertaler

Este artículo tiene como objetivo analizar, la incidencia que tienen actualmente las ONG s internacionales sobre la toma de decisiones de los gobiernos de diferentes Estados. Con el fin de hacer más específico dicho análisis, el trabajo se centra en el estudio del caso de la firma del Tratado de Libre Comercio entre Estados Unidos cuyo proceso, según se explica a lo largo del texto, se vio afectado de manera significativa por la acción de Human Rights Watch. El artículo presenta una exposición de la mecánica política requerida para la aprobación de este tipo de tratados en ambos países involucrados, así como la forma en que las asimetrías de poder entre ellos abrieron el campo a la acción de Human Rights Watch.This article has, as main objective, to analize the incidence of the international NGO s on the decisionmaking of the governments of the different States arround the world. To make even more specific this analysis, the working paper studies the case of the Free Trade Agreement between Colombia and the United States of America whose process, according to the text, was significantly affected by the action of Human Rights Watch. This paper also presents an exposition of the politic mechanic involves in the approval of this kind of agreements in both States, and in how the power asymmetries between them clean the field for Human Rights Watch´s action.Universidad del Rosari

Data in support of substrate flexibility of a mutated acyltransferase domain and implications for polyketide biosynthesis

Enzyme-directed mutasynthesis is an emerging strategy for the targeted derivatization of natural products. Here, data on the synthesis of malonic acid derivatives for feeding studies in Saccharopolyspora erythraea , the mutagenesis of DEBS and bioanalytical data on the experimental investigation of studies on the biosynthetic pathway towards erythromycin are presented

Data in support of substrate flexibility of a mutated acyltransferase domain and implications for polyketide biosynthesis

Enzyme-directed mutasynthesis is an emerging strategy for the targeted derivatization of natural products. Here, data on the synthesis of malonic acid derivatives for feeding studies in Saccharopolyspora erythraea , the mutagenesis of DEBS and bioanalytical data on the experimental investigation of studies on the biosynthetic pathway towards erythromycin are presented

Enzyme-Directed Mutasynthesis: A Combined Experimental and Theoretical Approach to Substrate Recognition of a Polyketide Synthase

Acyltransferase domains control the extender unit recognition in Polyketide Synthases (PKS) and thereby the side-chain diversity of the resulting natural products. The enzyme engineering strategy presented here allows the alteration of the acyltransferase substrate profile to enable an engineered biosynthesis of natural product derivatives through the incorporation of a synthetic malonic acid thioester. Experimental sequence–function correlations combined with computational modeling revealed the origins of substrate recognition in these PKS domains and enabled a targeted mutagenesis. We show how a single point mutation was able to direct the incorporation of a malonic acid building block with a non-native functional group into erythromycin. This approach, introduced here as enzyme-directed mutasynthesis, opens a new field of possibilities beyond the state of the art for the combination of organic chemistry and biosynthesis toward natural product analogues