Single Molecule DNA Sequencing by Fluorescent Nucleotide Reversible Terminators

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DESCRIPTION (provided by applicant): The ability to sequence a human genome with high accuracy and speed, and at low cost, is critical to the emerging field of personalized medicine. In response to this demand, our research team developed the novel method of DNA sequencing-by-synthesis (SBS) on a solid surface, which has been recognized as a successful new paradigm for deciphering DNA sequences. In this grant application, we will use molecular engineering approaches to take our successful SBS strategy to the next level by adapting it for single molecule sequencing using fluorescent reversible terminators. Template DNA molecules will be attached to a glass surface modified by covalent attachment of PEG-primers under conditions where as many as 1 billion clearly separated single molecules are attached to the slide and their location registered by the presence of a cleavable fluorescent moiety. SBS will then be conducted using reversible blocked nucleotides with an appropriate set of cleavable fluorophores. We have also developed a walking strategy that permits re-use of the template multiple times to increase SBS readlength. We will modify a TIRF microscope to create a device with an enhanced microfluidic flow cell platform to permit large-scale detection of single molecules during each cycle of SBS. Finally, we have designed a number of DNA library construction methods that avoid amplification and a paired-end sequencing strategies compatible with the single molecule SBS approach. This will permit us to test the system with real genomic DNA, cDNA and other templates from ongoing biomedical research collaborations. With a billion DNA templates immobilized on a chip at single molecule resolution, even 30 to 50 base reads will cover the entire human genome at good coverage on a single chip. Public Health Relevance: The realization of the need for personalized medicine has encouraged the development of technologies able to sequence the human genome with high accuracy and speed at low cost. To approach this goal, we have combined the concepts of our successful sequencing by synthesis and sequence walking method with the ability to utilize single molecules. The latter avoids the necessity of cloning or otherwise amplifying DNA before sequencing, which is in fact one of the most expensive and time consuming parts of the process, and can lead to undesirable biases in the DNA sequences. With a billion DNA molecules immobilized on a chip at single molecule resolution, even read lengths of 30 or 50 bases will provide the ability to sequence the entire human genome at high accuracy on a single sequencing chip.