title: Rational design of DNA-actuated enzyme nanoreactors guided by single molecule analysis.
abstract: The control of enzymatic reactions using nanoscale DNA devices offers a powerful application of DNA nanotechnology uniquely derived from actuation. However, previous characterization of enzymatic reaction rates using bulk biochemical assays reported suboptimal function of DNA devices such as tweezers. To gain mechanistic insight into this deficiency and to identify design rules to improve their function, here we exploit the synergy of single molecule imaging and computational modeling to characterize the three-dimensional structures and catalytic functions of DNA tweezer-actuated nanoreactors. Our analysis revealed two important deficiencies--incomplete closure upon actuation and conformational heterogeneity. Upon rational redesign of the Holliday junctions located at their hinge and arms, we found that the DNA tweezers could be more completely and uniformly closed. A novel single molecule enzyme assay was developed to demonstrate that our design improvements yield significant, independent enhancements in the fraction of active enzyme nanoreactors and their individual substrate turnover frequencies. The sequence-level design strategies explored here may aid more broadly in improving the performance of DNA-based nanodevices including biological and chemical sensors.
authors.affiliation: Department of Chemistry, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA. nwalter@umich.edu.
authors.forename: Soma
authors.initials: S
authors.lastname: Dhakal
authors.affiliation: Department of Biological Engineering, Laboratory for Computational Biology & Biophysics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. mark.bathe@mit.edu.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Adendorff
authors.affiliation: Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA. hao.yan@asu.edu.
authors.forename: Minghui
authors.initials: M
authors.lastname: Liu
authors.affiliation: Center for Molecular Design and Biomimetics, The Biodesign Institute, Arizona State University, Tempe, AZ 85287, USA and School of Molecular Sciences, Arizona State University, Tempe, AZ 85287, USA. hao.yan@asu.edu.
authors.forename: Hao
authors.initials: H
authors.lastname: Yan
authors.affiliation: Department of Biological Engineering, Laboratory for Computational Biology & Biophysics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. mark.bathe@mit.edu.
authors.forename: Mark
authors.initials: M
authors.lastname: Bathe
authors.affiliation: Department of Chemistry, Single Molecule Analysis Group, University of Michigan, Ann Arbor, MI 48109, USA. nwalter@umich.edu.
authors.forename: Nils G
authors.initials: NG
authors.lastname: Walter
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D005954:Glucosephosphate Dehydrogenase / Q000737:chemistry / Q000378:metabolism; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D056004:Molecular Dynamics Simulation; D036103:Nanotechnology; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism
chemical_list: D004798:Enzymes; D005456:Fluorescent Dyes; D009841:Oligonucleotides; D004247:DNA; D005954:Glucosephosphate Dehydrogenase