Helicos shoots for $5K genome
Helicos Biosciences is featured in this month’s MIT Technology Review. Helicos is developing sequencing technology based on the work of Stephen Quake. The article provides a description of how their sequence-by-synthesis method works:
Helicos’s technology eliminates many of the expensive and
time-consuming steps that are central to conventional DNA sequencing.
The machine works, in essence, by photographing the process of DNA
Technicians chop up the DNA to be sequenced into
short pieces just a few hundred letters long and split each piece into
single strands, which will serve as templates for new DNA copies. They
take about 1.2 billion of those templates and chemically anchor them
side by side, like tiny bristles, on a glass slide. The Helicos machine
then washes the slide with DNA-synthesizing enzymes and fluorescently
tagged versions of the DNA bases—the molecular building blocks
represented by the familiar DNA letters. It introduces copies of just
one base at a time; wherever a template strand calls for that letter in
the next open position, the enzymes incorporate it into the growing DNA
copy. The machine then washes out the extra, unincorporated bases and
takes a picture that reveals the newly incorporated bases as dots of
lights. Once it has captured an image, the device pumps in chemicals
that stop the new bases from glowing, in preparation for another cycle
of washes and photos. The Helicos machine repeats the whole
process over and over, building up the new DNA copies one letter at a
time. A computer analyzes all the captured images to determine the
sequence of each short strand; then, using the published human genome
sequence as a guide, it pieces all the short sequences together into a
single complete one.
The Helicos sequencing machines are expected to be commercially available by late 2006 or early 2007. How will the cost of sequencing a human genome on one of these machines compare to today’s standard?
"using about 100 state-of-the-art sequencing machines to fully sequence
the 3.2 billion DNA letters that make up one person’s genome would take
six months and cost $20 million to $30 million."
"When Helicos’s commercial machine is released,
says Lapidus, it will sequence a whole genome start to finish in three
days and for a cost of $5,000."
Corie Lok. "Deciphering DNA, Top Speed" MIT Tech Review. May 2005.
Stephen Quake Lab.