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DNA Sequences Shaped by Selection for Stability
 

Summary: DNA Sequences Shaped by Selection
for Stability
Martin Ackermann1,2*
, Lin Chao1
1 Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America, 2 ETH Zu¨rich, Theoretical Biology, Zurich, Switzerland
The sequence of a stretch of nucleotides affects its propensity for errors during replication and expression. Are
proteins encoded by stable or unstable nucleotide sequences? If selection for variability is prevalent, one could expect
an excess of unstable sequences. Alternatively, if selection against targets for errors were substantial, an excess of
stable sequences would be expected. We screened the genome sequences of different organisms for an important
determinant of stability, the presence of mononucleotide repeats. We find that codons are used to encode proteins in a
way that avoids the emergence of mononucleotide repeats, and we can attribute this bias to selection rather than a
neutral process. This indicates that selection for stability, rather than for the generation of variation, substantially
influences how information is encoded in the genome.
Citation: Ackermann M, Chao L (2006) DNA sequences shaped by selection for stability. PLoS Genet 2(2): e22.
Introduction
How faithfully a given stretch of nucleotides is replicated
and expressed depends not only on the machinery for DNA
and RNA processing in the cell, but also on the sequence of
the nucleotide stretch itself. Certain sequences are inherently
prone to errors during replication and expression, whereas

  

Source: Ackermann, Martin - Institut für Integrative Biologie, Eidgenössische Technische Hochschule Zürich (ETHZ)

 

Collections: Biology and Medicine