Protein-mediated DNA looping in a fluctuating micromechanical environment

Forces on the order of a hundred femtonewtons can drastically prevent the formation of protein-mediated DNA loops, which are a common regulatory component of cellular function and control. To investigate how such an acutely sensitive mechanism might operate within a noisy environment, as might typically be experienced within a cell, we have studied the response of DNA loop formation under an optically induced, fluctuating, mechanical tension. We show that mechanical noise strongly enhances the rate of loop formation. Moreover, the sensitivity of the loop formation rate to mechanical fluctuations is relatively independent of the baseline tension. This suggests that tension along the DNA molecule could act as a robust means of regulating transcription in a noisy in vivo environment.