Reverse engineering of an aspirin-responsive regulator in bacteria

Lummy Maria Oliveira Monteiro, Letícia Magalhães Arruda, Ananda Sanches Medeiros, Leonardo MartinsSantana, Luana de Fátima Alves, María-Eugenia Guazzaroni, Víctor de Lorenzo, and Rafael Silva-Rocha

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Sep 14, 2018
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Received Date: 4th September 2018

Bacterial transcriptional factors (TFs) and their target promoters are key devices for engineering of complex circuits in many biotechnological applications. Yet, there is a dearth of well characterized inducer-responsive TFs that could be used in the context of an animal or human host. In this work we have deciphered the inducer recognition mechanism of two AraC/XylS regulators from Pseudomonas putida (BenR and XylS) for creating a novel expression system responsive to acetyl salicylate (i.e. Aspirin). Using protein homology modeling and molecular docking with the cognate inducer benzoate and a suite of chemical analogues, we identified the conserved binding pocket of these two proteins. By means of site directed mutagenesis, we identified a single amino acid position required for efficient inducer recognition and transcriptional activation. While modification of this position in BenR abolishes protein activity, in XylS increases the response to several aromatic compounds, including acetyl salicylic acid to levels close to those achieved by the canonical inducer. Moreover, by constructing chimeric proteins with swapped N-terminal domains, we created novel regulators with mixed promoter and inducer recognition profiles. As a result, a collection of engineered TFs was generated with enhanced response to a well characterized and largely innocuous molecule with a potential for eliciting heterologous expression of bacterial genes in animal carriers.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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