BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Quantifying the invisible complexities of the genome - Alice Pyne (University of Sheffield) DTSTART:20231208T150000Z DTEND:20231208T153000Z UID:TALK208903@talks.cam.ac.uk DESCRIPTION:The complexity of cellular DNA is a consequence of its innate flexibility\, compaction in the nucleus\, and manipulation of its structur e by DNA-processing enzymes\, resulting in a vast conformational landscape . Within this landscape DNA adopts intricate structures\, conformations an d topologies and is frequently maintained under superhelical stress\, in a n under- or over- wound state. The effect of superhelical stress on the st ructure of DNA is challenging to quantify\, because of the length scale at which this occurs\, 100x less than the wavelength of light. We develop ne w microscopy and image analysis tools to determine how the structure of in dividual DNA molecules varies under superhelical stress\, and how this aff ects its interactions with DNA-binding proteins and therapeutic agents.\nH igh-resolution atomic force microscopy (AFM) is unique in its ability to v isualise DNA structure and interactions in liquid with sub-molecular resol ution without the need for labelling or averaging\, enabling routine visua lisation of highly flexible and dynamic molecules\, such as DNA\, with sub -molecular resolution [1]. To quantify the structural and conformational v ariability of these molecules\, we have developed TopoStats\, a high-throu ghput\, open-source Python package which enables us to measure the physica l properties of DNA molecules from AFM images\, from contour length\, thro ugh curvature\, writhe and even twist as they &lsquo\;explore&rsquo\; thei r complex conformational space [2]. We combine these measurements with ato mistic molecular dynamics simulations to demonstrate that DNA under superh elical stress is far richer in structure than can be observed in short lin ear sequences\, containing kinks and defects at the atomistic level [3]. W e build on this work to determine how DNA supercoiling affects the interac tions of DNA binding proteins. For example\, we determine the structure of the protein NDP52 and show that it binds specifically and with high affin ity to double-stranded DNA changing its local conformation [4]. \;\n[1 ] Pyne\, A et al. Small. 12\, 1053 (2014)[2] Beton\, JG et al. Methods 193 \, 68-79 (2021)[3] Pyne\, ALB*\, Noy A* et al. Nature Communications. 12\, 1053 (2021)[4] Dos Santos\, A et al. Nature Communications 14\, 2855 (202 3) LOCATION:Seminar Room 1\, Newton Institute END:VEVENT END:VCALENDAR