Optimization of Processive Enzymes for DNA Sequencing using Nanopores

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DESCRIPTION (provided by applicant): The long-term objective of this project is rapid, highly accurate, and inexpensive sequencing of long (up to 150 kb) single DNA strands with a nanopore based DNA sequencing device. Meeting this long-term objective requires precise control of DNA movement past a nanopore sequence detector, and improvement of nanopore sequence detector resolution between DNA bases. The specific aims of this proposal build upon progress made to date in these two areas by laboratories at the University of California, Santa Cruz (Akeson), University of Washington (Gundlach) and the University of Pennsylvania (Drndic). Individual laboratory expertise and knowledge will be integrated to accomplish four specific aims. Specific aim one extends promising results at UCSC with DNA polymerase Phi29, a "molecular step motor" able to precisely control DNA movement through a nanopore sequencer. This work will employ existing personnel and 12 years of success at UCSC with alpha hemolysin protein nanopores to extend understanding of Phi29 DNA polymerase function in a nanopore. Specific aim two evaluates Phi29 DNA polymerase function with two nanopores selected for their potentially superior base resolution to the alpha hemolysin nanopore. The first is MspA, a protein nanopore, which will be evaluated with Phi29 DNA polymerase by U of Washington and UCSC teams. This collaboration takes advantage of expertise with use of Phi29 DNAP at UCSC and expertise with MspA at U of Washington. The second nanopore, a solid state ultrathin silicon nitride pore with fluorescence detection, will be evaluated with Phi29 DNA polymerase by U of Penn (makers of the solid-state nanopore) and UCSC teams. The third specific aim improves DNA base resolution through increased differences in current signals from individual bases. This will be achieved by increased salt concentrations in the nanopore combined with use of salt tolerant DNA Polymerases. DNA polymerases from salt tolerant organisms will be isolated by extremophile experts currently at UCSC. Specific aim 4 will use all information gathered to generate proof of concept through sequencing of long (up to 48 KB) DNA strands using a nanopore sequencing device. Realization of this technology will provide the basis for a more complete understanding of individual genetic traits and predispositions in human and other populations.