Humans have somewhere
around 20,000 genes, and
scientists don’t know what
most of them do. Even
simpler bacterium
commonly used in scientific
experiments have 4,000 to
5,000 genes. If scientists
could figure out the
minimum number of genes
necessary for life, they
reasoned, that is the perfect
starting point to determine
the functions of those
genes.
Now a team led by
scientists from the J. Craig
Venter Institute in California
has synthesized a cell with
what they've determined is
the smallest number of
genes necessary for life:
473. Their research,
published today in Science,
answers a fundamental
question in biology, and
may soon make a la carte
synthetic cells available for
medical and industrial
applications.
This research builds upon
the scientists’ 2010 work in
which they created the first
self-replicating synthetic
bacterium, which had
almost twice the number of
genetic base pairs as the
new cell does. But reaching
the lowest number of genes
necessary in a cell took
longer than they expected.
The researchers had
somewhat specific criteria
for their new cell: It needed
to be self-replicating, and
needed to do so fast
enough that they could
observe it in the lab.
Starting with the genetic
code from the Mycoplasma
mycoides bacteria, the
researchers divvied the
genes into eight sections
that could be assessed
independently.
Little by little, the
researchers knocked out the
genes they suspected to be
non-essential. To their
surprise, they found a
number of genes they
called quasi-essential, pairs
of genes that typically work
in tandem. These genes can
still accomplish the same
function if just one gene is
knocked out, but can’t if
both are eliminated. The
researchers compared these
types of genes to the
engines on an airplane—“If
you remove the engine on
the right wing, the plane
can still fly and land, but
you don’t know it’s essential
until you remove the other
one,” said Craig Venter, one
of the study authors, in a
press conference yesterday.
In the end, the researchers
ended up with a cell that
had 473 genes, each of
which produces RNA or a
protein molecule. That’s not
the minimum number, they
say, but a minimum, since
they could have chosen one
or the other quasi-essential
gene, or changed their
parameters to let the cells
grow more slowly.
But even from this
minimum number, the
researchers still don’t know
the function of about a
third of those genes. That
shows them that scientists
still have a lot more to learn
about the fundamentals of
biology, which could shed
light on our understanding
of evolution and someday
help treat genetic diseases.
In the future, the
researchers plan to
investigate further into
those poorly understood
genes. They also plan to
soon offer synthetic cells on
demand, using their basic
cell as a simpler chassis to
create cells that could be
used to help edit pig
genomes to make their
organs transplantable in
humans, or to concoct new
antibacterial compounds, or
to help them adapt to a
specific environment.
It's a bit of a stretch to
think that this
understanding can help us
directly treat diseases
lurking in the human
genome. But as scientists
work to understand the
basic function of more
genes, it could be possible
in the distant future. “This is
the start of a new era, but it
won’t happen overnight,”
Venter said.

www.popsci.com/scientists-create-living-cell-with-minimum-number-genes?src=SOC&dom=tw