title: Identification of human and rat FAD-AMP lyase (cyclic FMN forming) as ATP-dependent dihydroxyacetone kinases.
abstract: Rat liver FAD-AMP lyase or FMN cyclase is the only known enzymatic source of the unusual flavin nucleotide riboflavin 4',5'-cyclic phosphate. To determine its molecular identity, a peptide-mass fingerprint of the purified rat enzyme was obtained. It pointed to highly related, mammalian hypothetical proteins putatively classified as dihydroxyacetone (Dha) kinases due to weaker homologies to biochemically proven Dha kinases of plants, yeasts, and bacteria. The human protein LOC26007 cDNA was used to design PCR primers. The product amplified from human brain cDNA was cloned, sequenced (GenBank Accession No. ), and found to differ from protein LOC26007 cDNA by three SNPs. Its heterologous expression yielded a protein active both as FMN cyclase and ATP-dependent Dha kinase, each activity being inhibited by the substrate(s) of the other. Cyclase and kinase activities copurified from rat liver extracts. Evidence supports that a single protein sustains both activities, probably in a single active center. Putative Dha kinases from other mammals are likely to be FMN cyclases too. Future work will profit from the availability of the structure of Citrobacter freundii Dha kinase, which contains substrate-interacting residues conserved in human Dha kinase/FMN cyclase.
authors.affiliation: Unidad de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Extremadura, 06080 Badajoz, Spain.
authors.forename: Alicia
authors.initials: A
authors.lastname: Cabezas
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Costas
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Pinto
authors.forename: Ana
authors.initials: A
authors.lastname: Couto
authors.forename: José Carlos
authors.initials: JC
authors.lastname: Cameselle
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D004098:Dihydroxyacetone / Q000494:pharmacology; D005486:Flavin Mononucleotide / Q000096:biosynthesis; D005182:Flavin-Adenine Dinucleotide / Q000494:pharmacology; D006801:Humans; D008099:Liver / Q000201:enzymology; D008969:Molecular Sequence Data; D019761:Phosphorus-Oxygen Lyases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D011994:Recombinant Proteins; C111331:riboflavin 4',5'-cyclic phosphate; D005182:Flavin-Adenine Dinucleotide; D005486:Flavin Mononucleotide; D000255:Adenosine Triphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C023132:glycerone kinase; D019761:Phosphorus-Oxygen Lyases; C111330:FMN cyclase; D004098:Dihydroxyacetone