TY - JOUR TI - Functional instability allows access to DNA in longer transcription Activator-Like effector (TALE) arrays AU - Geiger-Schuller, Kathryn AU - Mitra, Jaba AU - Ha, Taekjip AU - Barrick, Doug A2 - van Oijen, Antoine M A2 - Kuriyan, John A2 - Bogdanove, Adam J VL - 8 PY - 2019 DA - 2019/02/27 SP - e38298 C1 - eLife 2019;8:e38298 DO - 10.7554/eLife.38298 UR - https://doi.org/10.7554/eLife.38298 AB - Transcription activator-like effectors (TALEs) bind DNA through an array of tandem 34-residue repeats. How TALE repeat domains wrap around DNA, often extending more than 1.5 helical turns, without using external energy is not well understood. Here, we examine the kinetics of DNA binding of TALE arrays with varying numbers of identical repeats. Single molecule fluorescence analysis and deterministic modeling reveal conformational heterogeneity in both the free- and DNA-bound TALE arrays. Our findings, combined with previously identified partly folded states, indicate a TALE instability that is functionally important for DNA binding. For TALEs forming less than one superhelical turn around DNA, partly folded states inhibit DNA binding. In contrast, for TALEs forming more than one turn, partly folded states facilitate DNA binding, demonstrating a mode of ‘functional instability’ that facilitates macromolecular assembly. Increasing repeat number slows down interconversion between the various DNA-free and DNA-bound states. KW - TALE repeat KW - single-molecule biophysics KW - FRET KW - functional instability KW - deterministic modeling JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -