title: Ferredoxin:thioredoxin reductase (FTR) links the regulation of oxygenic photosynthesis to deeply rooted bacteria.
abstract: Uncovered in studies on photosynthesis 35 years ago, redox regulation has been extended to all types of living cells. We understand a great deal about the occurrence, function, and mechanism of action of this mode of regulation, but we know little about its origin and its evolution. To help fill this gap, we have taken advantage of available genome sequences that make it possible to trace the phylogenetic roots of members of the system that was originally described for chloroplasts-ferredoxin, ferredoxin:thioredoxin reductase (FTR), and thioredoxin as well as target enzymes. The results suggest that: (1) the catalytic subunit, FTRc, originated in deeply rooted microaerophilic, chemoautotrophic bacteria where it appears to function in regulating CO(2) fixation by the reverse citric acid cycle; (2) FTRc was incorporated into oxygenic photosynthetic organisms without significant structural change except for addition of a variable subunit (FTRv) seemingly to protect the Fe-S cluster against oxygen; (3) new Trxs and target enzymes were systematically added as evolution proceeded from bacteria through the different types of oxygenic photosynthetic organisms; (4) an oxygenic type of regulation preceded classical light-dark regulation in the regulation of enzymes of CO(2) fixation by the Calvin-Benson cycle; (5) FTR is not universally present in oxygenic photosynthetic organisms, and in certain early representatives is seemingly functionally replaced by NADP-thioredoxin reductase; and (6) FTRc underwent structural diversification to meet the ecological needs of a variety of bacteria and archaea.
authors.affiliation: Instituto de Recursos Naturales y Agrobiología de Salamanca, Salamanca, Spain. monica.balsera@irnasa.csic.es
authors.forename: Monica
authors.initials: M
authors.lastname: Balsera
authors.forename: Estefania
authors.initials: E
authors.lastname: Uberegui
authors.forename: Dwi
authors.initials: D
authors.lastname: Susanti
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Schmitz
authors.forename: Biswarup
authors.initials: B
authors.lastname: Mukhopadhyay
authors.forename: Peter
authors.initials: P
authors.lastname: Schürmann
authors.forename: Bob B
authors.initials: BB
authors.lastname: Buchanan
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002245:Carbon Dioxide / Q000378:metabolism; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000201:enzymology* / Q000235:genetics; D030541:Databases, Genetic; D019143:Evolution, Molecular; D005288:Ferredoxins / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D008027:Light; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D010802:Phylogeny; D010944:Plants / Q000145:classification / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D016415:Sequence Alignment
chemical_list: D001426:Bacterial Proteins; D060365:Chloroplast Proteins; D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D002245:Carbon Dioxide; D010088:Oxidoreductases; C021588:ferredoxin-thioredoxin reductase; D017853:Phosphotransferases (Alcohol Group Acceptor); C022390:phosphoribulokinase; D010100:Oxygen