title: Accumulation of adenine and thymine in a groE-homologous operon of an intracellular symbiont.
abstract: As a result of the nucleotide sequence analysis of an aphid endosymbiont's operon homologous to the Escherichia coli groE, we noted that directional base substitutions tending toward an increase of A + T content represent an obvious evolutionary trend in this prokaryotic operon, housed for a long period by an eukaryotic cell. This result, when taken together with previous reports, raised the possibility that genomic DNA of prokaryotes residing in an eukaryotic cell is subject to A/T-biased directional mutation pressure and/or both negative and positive selection operating under conditions specific to the intracellular environments.
authors.affiliation: Zoological Institute, Faculty of Science, University of Tokyo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Ohtaka
authors.forename: H
authors.initials: H
authors.lastname: Ishikawa
mesh_terms: D000225:Adenine / Q000378:metabolism*; D000818:Animals; D001042:Aphids / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D005075:Biological Evolution; D018833:Chaperonins; D003001:Cloning, Molecular; D003062:Codon; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D006090:Gram-Negative Bacteria / Q000235:genetics* / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009876:Operon; D012689:Sequence Homology, Nucleic Acid; D013559:Symbiosis; D013941:Thymine / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003062:Codon; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C028715:GroE protein, E coli; D006360:Heat-Shock Proteins; C044322:SymL protein, Bacteria; D018833:Chaperonins; D000225:Adenine; D013941:Thymine