title: Phylogenetic analysis of plastid origins based on secA sequences.
abstract: We have generated secA sequence data from a number of photosynthetic prokaryotes and carried out a phylogenetic analysis using secA sequences from prokaryotes, green plants, and red and brown algae. We have studied the substitution patterns that give rise to the apparent phylogenetic structure. We show that the high AT content of the plastid sequences significantly affects the amino-acid composition. We also show that most of the apparent evidence for an edge separating red and brown plastids from green plants within the phylogenetic tree is due to differences in nucleotide composition. The remaining apparent evidence is likely to be due, at least in part, to differences in the distribution of sites free to vary. We discuss the implications of this study for hypotheses of plastid origins.
authors.affiliation: Department of Biochemistry and Cambridge Centre for Molecular Recognition, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Barbrook
authors.forename: P J
authors.initials: PJ
authors.lastname: Lockhart
authors.forename: C J
authors.initials: CJ
authors.lastname: Howe
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics*; D020418:Algal Proteins / Q000235:genetics; D000596:Amino Acids / Q000032:analysis; D001426:Bacterial Proteins / Q000235:genetics*; D001692:Biological Transport / Q000235:genetics; D003001:Cloning, Molecular; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D009696:Nucleic Acids / Q000032:analysis; D010788:Photosynthesis / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D018087:Plastids / Q000235:genetics*; D000069816:SEC Translocation Channels; D000081416:SecA Proteins; D017422:Sequence Analysis, DNA
chemical_list: D020418:Algal Proteins; D000596:Amino Acids; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D009696:Nucleic Acids; D010940:Plant Proteins; D000069816:SEC Translocation Channels; D000251:Adenosine Triphosphatases; D000081416:SecA Proteins