Reference

Madariaga-Marcos et al. eLife 2019;8:e43812. DOI: 10.7554/eLife.43812portadaelife

Authors

Julene Madariaga-Marcos, Cesar L Pastrana, Gemma LM Fisher, Mark Simon Dillingham, Fernando Moreno-Herrero.

Abstract

/Bacillus subtilis/ ParB forms multimeric networks involving non-specific DNA binding leading to DNA condensation. Previously, we found that an excess of the free C-terminal domain (CTD) of ParB impeded DNA condensation or promoted decondensation of pre-assembled networks (Fisher et al., 2017). However, interpretation of the molecular basis for this phenomenon was complicated by our inability to uncouple protein binding from DNA condensation. Here, we have combined lateral magnetic tweezers with TIRF microscopy to simultaneously control the restrictive force against condensation and to visualise ParB protein binding by fluorescence. At non-permissive forces for condensation, ParB binds non-specifically and highly dynamically to DNA. Our new approach concluded that the free CTD blocks the formation of ParB networks by heterodimerisation with full length DNA-bound ParB. This strongly supports a model in which the CTD acts as a key bridging interface between distal DNA binding loci within ParB networks.

Description

En este trabajo hemos estudiado el papel del dominio C-terminal (CTD) de ParB de Bacillus subtilis en el mecanismo de condensación de ADN. ParB es una proteína que se encarga de organizar el ADN para su correcta repartición durante la división celular. Hemos demostrado que el CTD es capaz de unirse al ADN de manera no específica y de manera simultánea unirse a otras proteínas ParB. Este descubrimiento ha sido posible gracias a técnicas avanzadas de molécula individual basadas en pinzas magnéticas y fluorescencia que nosotros mismos desarrollamos.

 

 

foto grupo

 

REFERENCIA DEL GRUPO INVESTIGADOR

En el grupo de Fernando Moreno Herrero (en el Centro Nacional de Biotecnología) desarrollamos y empleamos técnicas de molécula individual (AFM, pinzas magnéticas y fluorescencia) para estudiar propiedades mecánicas de ácidos nucleicos y su interacción con proteínas. Concretamente, nos interesa el funcionamiento de proteínas involucradas en los procesos de reparación del ADN y mantenimiento de los cromosomas.

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