title: A Tetrahymena thermophila G4-DNA binding protein with dihydrolipoamide dehydrogenase activity.
abstract: G4-DNA is a four-stranded structure that is formed by guanine-rich sequences. We report here the purification and characterization of a novel G4-DNA binding protein from Tetrahymena thermophila, designated TGP2. TGP2 was found to preferentially bind to G4-DNA oligonucleotides with adjacent single-stranded domains containing phosphorylated 5' ends and the sequence element, 5'-ACTG-3'. The amino acid sequence of TGP2 has high similarity to dihydrolipoamide dehydrogenase (DLDH) from a variety of species, and TGP2 was shown to have DLDH activity. Purified DLDH from porcine heart and bovine intestinal mucosa were shown to bind specifically to G4-DNA oligonucleotides. On the basis of these results we conclude that TGP2 is DLDH in T. thermophila and suggest that the G4-DNA binding capability of TGP2/DLDH may be biologically relevant.
authors.affiliation: Department of Biochemistry and Biophysics, Iowa State University, Ames 50011, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kee
authors.forename: L
authors.initials: L
authors.lastname: Niu
authors.forename: E
authors.initials: E
authors.lastname: Henderson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008058:Dihydrolipoamide Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D019281:Dimerization; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D011485:Protein Binding; D015800:Protozoan Proteins; D013329:Structure-Activity Relationship; D013552:Swine; D016808:Tetrahymena thermophila / Q000201:enzymology*
chemical_list: D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D010761:Phosphorus Radioisotopes; D015800:Protozoan Proteins; C490648:TGP2 protein, Tetrahymena thermophila; D008058:Dihydrolipoamide Dehydrogenase