Biophysical Society Thematic Meeting - June 28-July 1, 2015

New Biological Frontiers Illuminated by Molecular Sensors and Actuators

Poster Abstracts

7-POS Board 7 Low-Noise, low-Capacitance Solid-State Nanopore Measurements at High Bandwidth for Biomolecule Analysis Chen-Chi Chien , Adrian Balan, Rebecca Engelke, David Niedzwiecki, Marija Drndic. University of Pennsylvania, Philadelphia, USA. Solid-state nanopores are promising single molecule sensors, yet their applications are still limited by relatively high noise and low bandwidth. We devised an integrated process to produce silicon nitride (SiN) nanopore membranes suspended on glass substrates, thus successfully lowering the chip capacitance. We obtain higher signal-to-noise ratios and better resolution in ionic current signals than previously reported in solid state nanopores at megahertz bandwidth. Specifically, we show measurements of ionic current during translocation of DNA molecules through thin SiN membrane nanopores of small diameters at megahertz bandwidths with enhanced ionic signal-to-noise ratios. We further discuss the potential of these results to pave the way towards identifying intramolecular DNA sequences with solid-state nanopores, and how these low capacitance glass chip devices could be used in other biomolecule sensing applications.

8-POS Board 8 Investigating the Coordination of Two ATPases in RecBCD Helicase Complex Using

Single-Molecule Fluorescence Chia-Chuan Cho , Hung-Wen Li. National Taiwan University, Taipei, Taiwan.

RecBCD is an essential trimeric enzyme complex that initiates homologous recombinational repair in E. coli. RecBCD complex contains single-stranded DNA nuclease and two DNA helicases with single-stranded DNA translocase activities with opposite polarities. Previously, we showed that RecB is a 3’-to-5’ single-stranded DNA translocase and RecD is a 5’-to-3’ one. Here, we use total internal reflection fluorescence microscopy to observe and analyze individual cy3-labeled ATP binding and turnover events during RecBCD unwinding at the single-molecule level. This allows us to characterize both ATPase activities of RecB and RecD as well as the coordination between both subunits.

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