title: Cloning and expression of a Clostridium kluyveri gene responsible for diaphorase activity.
abstract: A small enzyme showing diaphorase activity was purified from culture supernatant of Clostridium kluyveri and its N-terminal amino acid sequence was determined. This sequence identified a gene (diaA) encoding a protein (DiaA) of 229 amino acids with a predicted molecular weight of 24,981 in the genomic DNA sequence database of C. kluyveri constructed by the Research Institute of Innovative Technology for the Earth. The predicted protein was composed of a flavin reductase-like domain and a rubredoxin-like domain from its N-terminus. The diaA gene was cloned into an expression vector and expressed in an Escherichia coli recombinant. Recombinant enzyme rDiaA showed NADH/NADPH diaphorase activity with 2,6-dichlorophenolindophenol and nitro blue tetrazolium. The enzyme was most active at pH 8.0 at 40 degrees C. The UV-visible absorption spectrum and thin layer chromatography (TLC) analyses indicated that one rDiaA molecule contained a tightly bound FMN molecule as a prosthetic group. An iron molecule was also detected in an enzyme molecule.
authors.affiliation: Graduate School of Bioresources, Mie University, Tsu 514-8507, Japan.
authors.forename: Saikat
authors.initials: S
authors.lastname: Chakraborty
authors.forename: Makiko
authors.initials: M
authors.lastname: Sakka
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kimura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakka
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D003001:Cloning, Molecular / Q000379:methods; D047010:Clostridium kluyveri / Q000201:enzymology / Q000235:genetics*; D005486:Flavin Mononucleotide; D015870:Gene Expression; D005798:Genes, Bacterial; D007501:Iron; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D005486:Flavin Mononucleotide; D007501:Iron; D009245:NADH Dehydrogenase