One of the common reactions that occur during replication is formation of new peptide bonds, which form the backbone of proteins. Spontaneously reversing that type of reaction would take about 600 years, England says. The number of peptide bonds in a typical bacterium is about 1.6 billion, and the heat wattage needed to break all of those bonds is about 100 billion natural units.
"I would have to wait a really long time to see all of those bonds fall apart," England says.
By estimating the waiting time needed to observe a spontaneous reversal of replication, England calculated that the minimum amount of heat a bacterium needs to generate as it divides is a little more than one-sixth of the amount an E. coli cell actually produces during replication.
The finding suggests that bacteria could grow dramatically faster than they do now and still obey the second law of thermodynamics. England says that because cell replication is just one of the many tasks E. coli need to perform, it's unlikely they would evolve to their most efficient possible growth rate. However, for synthetic biology applications, it may be useful to create bacteria that can divide faster, which this paper shows is theoretically possible.
The paper may also offer some evidence for why DNA, and not RNA, evolved as the main form of genetic material, England says: DNA is more durable and doesn't spontaneously break its bonds as readily as RNA does. This means that RNA may have an advantage over DNA because it can grow faster and use up available resources. This supports a previously suggested hypothesis that RNA may have evolved first, before life arose on Earth, and DNA showed up later on.
"I think it's a helpful way of trying to get a little bit m
|Contact: Andrew Carleen|
Massachusetts Institute of Technology