title: Contrasting evolutionary histories of chloroplast thioredoxins f and m.
abstract: Fourteen thioredoxin sequences were used to construct a minimal phylogenetic tree by using parsimony. The bacterial thioredoxins clustered into three groups: one containing the photosynthetic purple bacteria, Escherichia and Corynebacterium; a second containing the photosynthetic green bacterium, Chlorobium; and a third containing cyanobacteria. These groupings are similar to those generated from earlier 16s RNA analyses. Animal thioredoxins formed a fourth group. The two thioredoxins of chloroplasts (f and m) showed contrasting phylogenetic patterns. As predicted from prior studies, spinach chloroplast thioredoxin m grouped with its counterparts from cyanobacteria and eukaryotic algae, but, unexpectedly, thioredoxin f grouped with the animal thioredoxins. The results indicate that, during evolution, thioredoxin m of contemporary photosynthetic eukaryotic cells was derived from a prokaryotic symbiont, whereas thioredoxin f descended from an ancestral eukaryote common to plants and animals. The findings illustrate the potential of thioredoxin as a phylogenetic marker and suggest a relationship between the animal and f-type thioredoxins.
authors.affiliation: Department of Plant Biology, University of California, Berkeley 94708.
authors.forename: H
authors.initials: H
authors.lastname: Hartman
authors.forename: M
authors.initials: M
authors.lastname: Syvanen
authors.forename: B B
authors.initials: BB
authors.lastname: Buchanan
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D005075:Biological Evolution; D000460:Chlorophyta / Q000235:genetics; D054479:Chloroplast Thioredoxins; D002736:Chloroplasts / Q000032:analysis*; D006801:Humans; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D010944:Plants / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013879:Thioredoxins / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D054479:Chloroplast Thioredoxins; D010940:Plant Proteins; D013879:Thioredoxins