Presentation day

Wednesday  7:00 PM

TITLE

Systematic manipulation of DNA functionality by controlled self-assembly and disassembly

Abstract

In chromosomes DNA exists in highly organized state, where it is wrapped around
histones (structural proteins), forming a composite material called chromatin.
Decondensation of the DNA plays an essential role in gene expression. DNA has to be unpacked for the
transcription (RNA synthesis) and it arouses interest in understanding underlying electrostatic interaction
mechanisms of DNA decompaction.
We unravel the structure and function and monitor the real–time dynamics of the formed self-assemblies of
DNA with artificial cationic dendrimers. The high flexibility of microfluidics techniques allows us to control
mixing speeds, reaction times, and flow fields. In particular, the laminar flow conditions inside
microchannels provide the possibility to investigate interaction processes in a time-resolved manner.
Diffusive mixing in microchannels creates tunable reaction conditions with defined changes in local
concentrations. Furthermore, we study and emulate by which mechanisms nature deals with locally on/off
DNA condensation. We analyze the dynamics of DNA/artificial histone complexes unpacking by anionic
competitor molecules. Here, the negatively charged molecules compete with phosphate groups of DNA to
interact with positively charged groups of histone-mimicking dendrimers. We employ a potent combination
of techniques involving microfluidics and small angle X-ray scattering (SAXS) in order to analyze the impact
of self-assembly and disassembly on gene functionality.