The sea urchin mitochondrial transcription factor A binds and bends DNA efficiently despite its unusually short C-terminal tail.
Mitochondrial transcription factor A (TFAM) is a key component for the protection and transcription of the mitochondrial genome. TFAM belongs to the high mobility group (HMG) box family of DNA binding proteins that are able to bind to and bend DNA. Human TFAM (huTFAM) contains two HMG box domains separated by a linker region, and a 26 amino acid C-terminal tail distal to the second HMG box. Previous studies on huTFAM have shown that requisites for proper DNA bending and specific binding to the mitochondrial genome are specific intercalating residues and the C-terminal tail. We have characterized TFAM from the sea urchin Paracentrotus lividus (suTFAM). Differently from human, suTFAM contains a short 9 amino acid C-terminal tail, yet it still has the ability to specifically bind to mtDNA. To provide information on the mode of binding of the protein we used fluorescence resonance energy transfer (FRET) assays and found that, in spite of the absence of a canonical C-terminal tail, suTFAM distorts DNA at a great extent and recognizes specific target with high affinity. Site directed mutagenesis showed that the two Phe residues placed in corresponding position of the two intercalating Leu of huTFAM are responsible for the strong bending and the great binding affinity of suTFAM.
School of Pharmacy, Rueckert-Hartman College for Health Professions, Regis University 3333 Regis Boulevard, H-28, Denver, CO 80221, USA.
Christopher S
CS
Malarkey
Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy.
Claudia
C
Lionetti
Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy.
Stefania
S
Deceglie
Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy.
Marina
M
Roberti
Department of Pharmacology and the Program in Structural Biology and Biochemistry, University of Colorado School of Medicine, 12801 East 17th Avenue, Aurora, CO 80045, USA.
Mair E A
ME
Churchill
Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy; National Research Council of Italy, Institute of Biomembranes and Bioenergetics, Italy. Electronic address: palmiro.cantatore@uniba.it.
Palmiro
P
Cantatore
Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Via E. Orabona 4, 70125, Bari, Italy. Electronic address: paolaannamaria.loguerciopolosa@uniba.it.
Paola
P
Loguercio Polosa
D000595:Amino Acid Sequence; D000818:Animals; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000378:metabolism*; D031541:Fluorescence Resonance Energy Transfer; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D012617:Sea Urchins / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D004272:DNA, Mitochondrial; D024101:Mitochondrial Proteins; D014157:Transcription Factors
DNA-bending; FRET; HMG box proteins; Mitochondrial transcription factor A (TFAM); Sea urchin mitochondria