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Life's code rewritten in four-letter words
- 17 February 2010 by Linda Geddes
- Magazine issue 2748
Editorial: The
scary business of tinkering with life
A TOTALLY new genetic code has been devised, along with machinery that
could make it a biological reality. It's an advance that means living cells
could be persuaded to make proteins with properties that have never been seen
in the natural world.
More extraordinary still, it could eventually lead to the creation of new
or "improved" life forms that incorporate these materials in their
tissue - possibly even organisms with bulletproof bodies.
In all existing life forms, the cell's protein-making machinery reads the
four chemical "letters" of DNA - called nucleotides - in triplets to
make chains of amino acids. Each three-letter word embodies the code for a
single amino acid or tells the cell to stop making a protein chain.
Not any more. Jason
Chin at the University of Cambridge and his colleagues have redesigned the
cell's machinery ...
http://www.newscientist.com/article/mg20527484.000-lifes-code-rewritten-in-fourletter-words.html?DCMP=OTC-rss&nsref=life
London, Feb 15 : Scientists at the University of Cambridge have created a new
way of using the genetic code, allowing proteins
to be made with properties that have never been seen in the natural world.
According to Jason Chin and his colleagues from the
university, the breakthrough could eventually lead to the creation of new or
''improved'' life forms incorporating these new materials into their tissue.
In all existing life forms, the four ''letters'' of the
genetic code, called nucleotides, are read in triplets, so that every three
nucleotides encode a single amino
acid .
Chin and colleagues have now redesigned the cell''s machinery
so that it reads the genetic code in quadruplets.
In the genetic code that life has used up to now, there are
64 possible triplet combinations of the four-nucleotide letters; these genetic
"words" are called codons.
Each codon either codes for an amino acid or tells the cell
to stop making a protein
chain.
Now Chin''s team has created 256 blank four-letter codons
that can be assigned to amino
acids
that don''t even exist yet.
To achieve this, the team had to redesign three pieces of the
cellular machinery that make proteins.
The researchers went on to prove their new genetic code works
by assigning two "unnatural" amino acids to their quadruplet codons,
and incorporated them into a protein chain.
"It''s the beginning of a parallel genetic code,"
New Scientist quoted Chin as saying.
They''ve also shown that these amino acids can react with
each other to form a different kind of chemical bond to those, which usually
hold proteins together in their three-dimensional shape.
The normal kind of bonds - disulphide bonds - can be broken
by changes in heat and acidity, causing proteins to lose their 3D structure.
However, the bonds created between Chin''s new amino acids
are stronger - and so could allow proteins to work in a much wider range of
environments.
For instance, this could help make drugs that can be taken
orally without being destroyed by the acids in the digestive
tract.
The study appears in the Journal Nature. (ANI)
http://www.topnews.in/health/scientists-revamp-genetic-coding-26233
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