In:
Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 94, No. 15 ( 1997-07-22), p. 7784-7790
Kurzfassung:
We first review what is known about patterns of codon usage bias in Drosophila and make the following points:
( i ) Drosophila genes are as biased or
more biased than those in microorganisms. ( ii ) The level
of bias of genes and even the particular pattern of codon bias can remain phylogenetically invariant for very long periods of evolution.
( iii ) However, some genes, even very tightly linked
genes, can change very greatly in codon bias across species. ( iv ) Generally G and especially C are favored at
synonymous sites in biased genes. ( v ) With the exception
of aspartic acid, all amino acids contribute significantly and about equally to the codon usage bias of a gene. ( vi ) While
most individual amino acids that can use G or C at synonymous sites display a preference for C, there are exceptions: valine and leucine, which prefer G. ( vii ) Finally, smaller genes tend to be
more biased than longer genes. We then examine possible causes of these patterns and discount mutation bias on three bases: there is little
evidence of regional mutation bias in Drosophila, mutation bias is likely toward A+T (the opposite of codon usage bias),
and not all amino acids display the preference for the same nucleotide in the wobble position. Two lines of evidence support a selection
hypothesis based on tRNA pools: highly biased genes tend to be highly and/or rapidly expressed, and the preferred codons in highly biased
genes optimally bind the most abundant isoaccepting tRNAs. Finally, we examine the effect of bias on DNA evolution and confirm that genes with
high codon usage bias have lower rates of synonymous substitution between species than do genes with low codon usage bias. Surprisingly,
we find that genes with higher codon usage bias display higher levels of intraspecific synonymous polymorphism. This may be due to opposing
effects of recombination.
Materialart:
Online-Ressource
ISSN:
0027-8424
,
1091-6490
DOI:
10.1073/pnas.94.15.7784
Sprache:
Englisch
Verlag:
Proceedings of the National Academy of Sciences
Publikationsdatum:
1997
ZDB Id:
209104-5
ZDB Id:
1461794-8
SSG:
11
SSG:
12
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