Real-time imaging of sulfhydryl single-stranded DNA aggregation

Abstract

The structure and functionality of biomacromolecules are often regulated by chemical bonds, however, the regulation process and underlying mechanisms have not been well understood. Here, by using in situ liquid-phase transmission electron microscopy (LP-TEM), we explored the function of disulfide bonds during the self-assembly and structural evolution of sulfhydryl single-stranded DNA (SH-ssDNA). Sulfhydryl groups could induce self-assembly of SH-ssDNA into circular DNA containing disulfide bonds (SS-cirDNA). In addition, the disulfide bond interaction triggered the aggregation of two SS-cirDNA macromolecules along with significant structural changes. This visualization strategy provided structure information at nanometer resolution in real time and space, which could benefit future biomacromolecules research.

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“…For soft materials, the dynamics and degradation of ssDNA in D 2 O were captured at a dose rate of 8.4 e − /(Å 2 s) ( SI Appendix , Fig. S18 and Movie S7 ), lower than the reported damaging threshold [110 e − /(Å 2 s)] ( 66 , 67 ). In all systems, consistent with previous reports on nanoparticles ( 68 ) and micelles in SiN liquid cells ( 69 ), synthetic macromolecules ( 16 ), and DNA molecules ( 31 ) in the GLCs, as well as macromolecules imaged with optical microscopy ( 70 ), we observed the characteristic surface-mediated long hops of single particle trajectories.…”