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Neighboring base composition is strongly correlated with base substitution bias in a region of the chloroplast genome

Neighboring base composition is strongly correlated with base substitution bias in a region of... Nucleotide sequence from a region of the chloroplast genome is presented for 12 species spanning four subfamilies of the grass family. The region contains the coding sequence for the rbcL gene and the intergenic spacer between the gene coding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase rbcL and the photosystem I gene psal. This intergenic spacer contains a pseudogene for rpl23 as well as two noncoding segments with different A+T contents. Using the sequence of rbcL a chloroplast phylogeny of this family was constructed by parsimony. Variable sites of the two noncoding segments were traced onto the phylogeny to study the dynamics of base substitution. This was also performed for the fourfold-degenerate sites of the rbcL gene. A wide variation in transversion/transition is observed between the two noncoding segments and between the noncoding DNA and the fourfold-degenerate sites of rbcL This variation is correlated with regional A+T content. As regional A+T content decreases, the ratio of transversions to transitions also decreases. Substitutions were then scored in relation to neighboring base composition. The composition of the two bases immediately flanking each substitution is highly correlated with the transversion/transition bias. When both the 5′ and 3′ flanking bases are an A or a T, transversions are observed 2.2 times as frequently as transitions. When either or both neighbors are a C or a G, the opposite trend is found; transitions are observed 1.5 times more frequently than transversions. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Molecular Evolution Springer Journals

Neighboring base composition is strongly correlated with base substitution bias in a region of the chloroplast genome

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References (45)

Publisher
Springer Journals
Copyright
Copyright © 1995 by Springer-Verlag New York Inc
Subject
Life Sciences; Evolutionary Biology; Microbiology; Plant Sciences; Plant Genetics and Genomics; Animal Genetics and Genomics; Cell Biology
ISSN
0022-2844
eISSN
1432-1432
DOI
10.1007/BF00175818
Publisher site
See Article on Publisher Site

Abstract

Nucleotide sequence from a region of the chloroplast genome is presented for 12 species spanning four subfamilies of the grass family. The region contains the coding sequence for the rbcL gene and the intergenic spacer between the gene coding the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase rbcL and the photosystem I gene psal. This intergenic spacer contains a pseudogene for rpl23 as well as two noncoding segments with different A+T contents. Using the sequence of rbcL a chloroplast phylogeny of this family was constructed by parsimony. Variable sites of the two noncoding segments were traced onto the phylogeny to study the dynamics of base substitution. This was also performed for the fourfold-degenerate sites of the rbcL gene. A wide variation in transversion/transition is observed between the two noncoding segments and between the noncoding DNA and the fourfold-degenerate sites of rbcL This variation is correlated with regional A+T content. As regional A+T content decreases, the ratio of transversions to transitions also decreases. Substitutions were then scored in relation to neighboring base composition. The composition of the two bases immediately flanking each substitution is highly correlated with the transversion/transition bias. When both the 5′ and 3′ flanking bases are an A or a T, transversions are observed 2.2 times as frequently as transitions. When either or both neighbors are a C or a G, the opposite trend is found; transitions are observed 1.5 times more frequently than transversions.

Journal

Journal of Molecular EvolutionSpringer Journals

Published: Jul 5, 2004

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