title: The presence of four iron-containing superoxide dismutase isozymes in trypanosomatidae: characterization, subcellular localization, and phylogenetic origin in Trypanosoma brucei.
abstract: Metalloenzymes such as the superoxide dismutases (SODs) form part of a defense mechanism that helps protect obligate and facultative aerobic organisms from oxygen toxicity and damage. Here, we report the presence in the trypanosomatid genomes of four SOD genes: soda, sodb1, sodb2, and a newly identified sodc. All four genes of Trypanosoma brucei have been cloned (Tbsods), sequenced, and overexpressed in Escherichia coli and shown to encode active dimeric FeSOD isozymes. Homology modeling of the structures of all four enzymes using available X-ray crystal structures of homologs showed that the four TbSOD structures were nearly identical. Subcellular localization using GFP-fusion proteins in procyclic insect trypomastigotes shows that TbSODB1 is mainly cytosolic, with a minor glycosomal component, TbSODB2 is mainly glycosomal with some activity in the cytosol, and TbSODA and TbSODC are both mitochondrial isozymes. Phylogenetic studies of all available trypanosomatid SODs and 106 dimeric FeSODs and closely related cambialistic dimeric SOD sequences suggest that the trypanosomatid SODs have all been acquired by more than one event of horizontal gene transfer, followed by events of gene duplication.
authors.affiliation: Institut Pasteur, Inserm U547, 1 Rue du Professeur Calmette, B. P. 245, F-59019 Lille cedex, France.
authors.forename: Fabienne
authors.initials: F
authors.lastname: Dufernez
authors.forename: Cédric
authors.initials: C
authors.lastname: Yernaux
authors.forename: Delphine
authors.initials: D
authors.lastname: Gerbod
authors.forename: Christophe
authors.initials: C
authors.lastname: Noël
authors.forename: Mélanie
authors.initials: M
authors.lastname: Chauvenet
authors.forename: René
authors.initials: R
authors.lastname: Wintjens
authors.forename: Virginia P
authors.initials: VP
authors.lastname: Edgcomb
authors.forename: Monique
authors.initials: M
authors.lastname: Capron
authors.forename: Fred R
authors.initials: FR
authors.lastname: Opperdoes
authors.forename: Eric
authors.initials: E
authors.lastname: Viscogliosi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D007501:Iron / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics*; D014346:Trypanosoma brucei brucei / Q000201:enzymology*
chemical_list: D007527:Isoenzymes; D007501:Iron; D013482:Superoxide Dismutase