title: Lysine degradation through the saccharopine pathway in bacteria: LKR and SDH in bacteria and its relationship to the plant and animal enzymes.
abstract: Lysine degradation through the saccharopine pathway has been shown only in plants and animals. Here, we show that bacteria possess the genes encoding lysine-ketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH). In Silicibacter, the contiguous lkr and sdh genes are interspersed, in another frame, by a polypeptide of unknown function. The bacterial enzyme does not contain the 110-amino-acid interdomain (ID) that intersperses the LKR and SDH domains of the plant enzyme. The ID was found in Cyanobacteria interspersing polypeptides without similarities and activities of LKR and SDH. The LKR/SDH bifunctional polypeptide of animals and plants may have arisen from a α-proteobacterium with a configuration similar to that of Silicibacter, whereas the ID in the plant enzyme may have been inherited from Cyanobacteria.
authors.affiliation: Centro de Biologia Molecular e Engenharia Genética, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil.
authors.forename: Guilherme Coutinho de Mello
authors.initials: GC
authors.lastname: Serrano
authors.forename: Thaís
authors.initials: T
authors.lastname: Rezende e Silva Figueira
authors.forename: Eduardo
authors.initials: E
authors.lastname: Kiyota
authors.forename: Natalia
authors.initials: N
authors.lastname: Zanata
authors.forename: Paulo
authors.initials: P
authors.lastname: Arruda
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000201:enzymology; D001419:Bacteria / Q000201:enzymology*; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives* / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012443:Saccharopine Dehydrogenases / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D011994:Recombinant Proteins; D012443:Saccharopine Dehydrogenases; D008239:Lysine; C100169:saccharopine