title: Characterization of the sea urchin mitochondrial transcription factor A reveals unusual features.
abstract: Sea urchin mtDNA is transcribed via a different mechanism compared to vertebrates. To gain information on the apparatus of sea urchin mitochondrial transcription we have characterized the DNA binding properties of the mitochondrial transcription factor A (TFAM). The protein contains two HMG box domains but, differently from vertebrates, displays a very short C-terminal tail. Phylogenetic analysis showed that the distribution of tail length is mixed in the different lineages, indicating that it is a trait that undergoes rapid changes during evolution. Homology modeling suggests that the protein adopts the same configuration of the human counterpart and possibly a similar mode of binding to DNA. DNase I footprinting showed that TFAM specifically contacts mtDNA at a fixed distance from three AT-rich consensus sequences that were supposed to act as transcriptional initiation sites. Bound sequences are homologous and contain an inverted repeat motif, which resembles that involved in the intercalation of human TFAM in LSP DNA. The here reported data indicate that sea urchin TFAM specifically binds mtDNA. The protein could intercalate residues at the DNA inverted motif and, despite its short tail, might have a role in mitochondrial transcription.
authors.affiliation: Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70125 Bari, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Deceglie
authors.affiliation: Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70125 Bari, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Lionetti
authors.affiliation: Max Planck Institute for Biology of Ageing, Robert-Koch-Strasse 21, 50931 Cologne, Germany.
authors.forename: James B
authors.initials: JB
authors.lastname: Stewart
authors.affiliation: Max Planck Institute for Biology of Ageing, Robert-Koch-Strasse 21, 50931 Cologne, Germany.
authors.forename: Bianca
authors.initials: B
authors.lastname: Habermann
authors.affiliation: Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70125 Bari, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Roberti
authors.affiliation: Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70125 Bari, Italy.
authors.forename: Palmiro
authors.initials: P
authors.lastname: Cantatore
authors.affiliation: Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona, 4, 70125 Bari, Italy. Electronic address: paolaannamaria.loguerciopolosa@uniba.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Loguercio Polosa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018983:DNA Footprinting; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014644:Genetic Variation; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D012617:Sea Urchins / Q000235:genetics*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; D014157:Transcription Factors; C422562:mitochondrial transcription factor A
keywords: DNA binding; Mitochondria; Sea urchin; TFAM; mtDNA transcription