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Issue 21, 2020
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Polyamines stimulate RecA-mediated recombination by condensing duplex DNA and stabilizing intermediates

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Abstract

Polyamines are naturally occurring cationic molecules in cells. In addition to their roles in modulating gene expression and cell proliferation, they have been shown to stimulate DNA recombination. The molecular mechanism for stimulation is not clear. We utilized single-molecule tethered particle motion (TPM) experiments to investigate how polyamines stimulate RecA-mediated recombination. We showed that natural polyamines, spermine and spermidine, condense duplex DNA, but with different efficiencies. While ∼300 μM of spermine condenses 50% of duplex DNA, 2.0 mM of spermidine is required to achieve the same level of condensation. The condensation takes place in a stepwise manner, and is reversible upon removal of polyamines. We also showed that addition of polyamines stimulates the duplex capture activity of RecA filament and stabilizes the intermediates with longer dwell time. Through condensing duplex DNA and stabilizing the complex of RecA filaments and duplex DNA, polyamines stimulate the formation of functional intermediates by ∼20-fold, and promote recombination progression.

Graphical abstract: Polyamines stimulate RecA-mediated recombination by condensing duplex DNA and stabilizing intermediates

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Supplementary files

Article information


Submitted
25 Feb 2020
Accepted
14 May 2020
First published
14 May 2020

Phys. Chem. Chem. Phys., 2020,22, 11928-11935
Article type
Paper

Polyamines stimulate RecA-mediated recombination by condensing duplex DNA and stabilizing intermediates

N. E. Tirtom, Y. Hsu and H. Li, Phys. Chem. Chem. Phys., 2020, 22, 11928
DOI: 10.1039/D0CP01061H

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