TY - JOUR
T1 - Functional instability allows access to DNA in longer transcription activator-like effector (Tale) arrays
AU - Schuller, Kathryn Geiger
AU - Mitra, Jaba
AU - Ha, Taekjip
AU - Barrick, Doug
N1 - Funding Information:
KGS was provided by NIH training grant T32-GM008403. Support for this project was
Funding Information:
provided by NIH grant 1R01-GM068462 to DB and GM112659 to TH and NSF grant
Funding Information:
The authors acknowledge the support of the Center for Molecular Biophysics at Johns
Publisher Copyright:
© Severson et al.
PY - 2019/2
Y1 - 2019/2
N2 - 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.
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 - Deterministic modeling
KW - FRET
KW - Functional instability
KW - Single-molecule biophysics
KW - TALE repeat
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U2 - 10.7554/eLife.38298
DO - 10.7554/eLife.38298
M3 - Article
C2 - 30810525
AN - SCOPUS:85064243805
SN - 2050-084X
VL - 8
JO - eLife
JF - eLife
M1 - e38298
ER -