[ Follow Ups ]
Posted by Jean-Jacques Kupies on April 30, 1999 at 11:39:06:
In his message "hierarchical metabolic network evolution" posted on April 19, 1999, Frank Bruggeman wrote:
I'm wondering to what extent a hierarchical metabolic network (incorporating
DNA, RNA, protein, metabolism) linked by mass flow and allosteric interaction
is evolovable and what extent the evolvebility depends upon the metabolic
network
architecture. If any of you know of any literature on the subject please let
me know.
Frank Bruggeman
Biophycist
An excellent
article on this subject has been published in BioEssays
20(2):181-6, 1998
The authors provide a strong argument that metabolic reactions are not very
specific (sloppy, degenerately specific), and then conclude:
'Metabolic plasticity [due to sloppiness-JJK] ... coupled with natural
selection,
probably provides the driving force in the evolution of new metabolic
pathways...'
Here is the abstract:
D'Ari R, Casadesus J: Underground metabolism. Bioessays
20(2):181-186,
1998
All enzymes are able to use alternative substrates. When these are
naturally
occurring metabolites, an 'underground reaction' takes place. Examples are
presented
in which underground metabolism of this sort produces an observable phenotype.
Although biological processes can be remarkably accurate, evolution has
selected
error rates far from perfect. It is suggested here that a certain level of
metabolic
inaccuracy, in addition to saving energy, may also confer an evolutionary
advantage,
for example by providing metabolic plasticity. Since underground reactions are
unpredictable from DNA sequence data, caution is in order when interpreting
correlations between genetic disorders and pathological syndromes.