The Tension on dsDNA Bound to ssDNA/RecA Filaments May Play an Important Role in Driving Efficient and Accurate Homology Recognition and Strand Exchange

TL;DR

This paper presents an analytical model showing how tension in extended dsDNA bound to RecA filaments influences homology recognition and strand exchange, potentially enhancing accuracy through mechanical energy changes.

Contribution

It introduces a new analytical model quantifying tension distribution in dsDNA during strand exchange, linking mechanical forces to homology recognition.

Findings

Tension distribution affects homology stringency

Non-linear energy increase promotes accurate strand exchange

Model explains experimental observations of DNA/RecA interactions

Abstract

It is well known that during homology recognition and strand exchange the double stranded DNA (dsDNA) in DNA/RecA filaments is highly extended, but the functional role of the extension has been unclear. We present an analytical model that calculates the distribution of tension in the extended dsDNA during strand exchange. The model suggests that the binding of additional dsDNA base pairs to the DNA/RecA filament alters the tension in dsDNA that was already bound to the filament, resulting in a non-linear increase in the mechanical energy as a function of the number of bound base pairs. This collective mechanical response may promote homology stringency and underlie unexplained experimental results.