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Voyage of RepA protein from plasmid DNA replication through amyloid aggregation towards synthetic biology

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Author(s): Rafael Giraldo | Maria Elena Fernandez-Tresguerres

Journal: Journal of Applied Biomedicine
ISSN 1214-021X

Volume: 8;
Issue: 3;
Start page: 151;
Date: 2010;
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Keywords: plasmid replication | protein amyloids | protein-DNA interactions | RepA protein | synthetic biology

ABSTRACT
DNA replication of plasmids in Gram-negative bacteria has been an object of study at CIB-CSIC for nearly30 years. We have been focused on the enterobacterial antibiotic resistance factor R1 (1981–1992) and thepPS10 replicon from the phytopathogen Pseudomonas savastanoi (since 1984). Our group has usedmultidisciplinary (genetic, biochemical and biophysical-structural) approaches to unravel the molecularmechanism for the activation of RepA. Rep-type plasmidic proteins are either transcriptional repressors orreplication initiators/inhibitors, depending on their association state (dimers vs. monomers) and targeting ofalternative (operator or iteron) DNA sites. We discovered that allosteric DNA-binding remodels the structureof RepA N-terminal domain (WH1), transforming α-helical portions into β-strands. This precisely tunes thedistances between the DNA reading heads in WH1 and the C-terminal domain (WH2), to match the targetoperator or iteron sequences. We have recently moved into engineering such structural transformation inRepA-WH1 to build-up synthetic protein devices that allow for customized ligand (DNA)-promotedamyloidogenesis. Our basic studies on plasmid DNA replication are relevant for settling the bases of aminimalist bacterial model to tackle transmissible amyloid proteinopathies and are a valuable tool forbottom-up synthetic biology.
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