Nucleic Acids Packaging Processes: Effects of Adenine Tracts and Sequence-Dependent Curvature

Publisher Website
Google Scholar
Abstract
The effects of short runs of adenines (A-tracts) upon nucleic acids packaging processes and the properties of the resulting condensates were investigated by using random DNA sequences isolated from natural sources, as well as synthetic segments obtained by an extensive ligation of specific oligomers. Reiteration of short A-tracts (AN where N3), in which the distinct structural features that characterize this motif are fully expressed, results in a complete suppression of any chiral order in the packed particles, assigned to a significantly enhanced rigidity. DNA fragments where A-tracts are reiterated in phase, leading to a stable macroscopic curvature, are found to undergo condensation through altered pathways and to form toroidal shapes of unusually small dimensions. The results point towards the intriguing possibility that A-tracts and, in particular, the global, intrinsic curvature associated with such motifs, might be involved in the determination of nucleic acids packaging pathways, and underline the usefulness of defined sequences in the study of DNA condensation processes.