Researchers from the University of Washington have developed a sensor capable of sequencing a single DNA molecule. The sensor is based around a genetically engineered protein nanopore and has an opening one billionth of a meter wide, just wide enough for a single DNA strand to pass through.
The nanopore is placed in a membrane surrounded by potassium-chloride, and by applying a small voltage across the membrane an ionic current flow is created through the nanopore. Each type of DNA nucleotide – cytosine, guanine, adenine and thymine – which makes up the DNA sequence, affects the ionic current flow in different ways, allowing for nucleotide identification using these electrical current signatures.
A key element in developing the nanoscale DNA sensor was controlling the rate of DNA translocation through the pore using a molecular motor as described by Prof. Jens Gundlach who led the research team:
“The motor pulls the strand through the pore at a manageable speed of tens of milliseconds per nucleotide, which is slow enough to be able to read the current signal.”
The researchers have published their findings online this week in the journal Nature Biotechnology where they described the successful sequencing of 6 strands of DNA using the technique.
University of Washington press release: Tiny reader makes fast, cheap DNA sequencing feasible…
Abstract in Nature Biotechnology: Reading DNA at single-nucleotide resolution with a mutant MspA nanopore and phi29 DNA polymerase