title: The human mitochondrial transcription factor A is a versatile G-quadruplex binding protein.
abstract: The ability of the guanine-rich strand of the human mitochondrial DNA (mtDNA) to form G-quadruplex structures (G4s) has been recently highlighted, suggesting potential functions in mtDNA replication initiation and mtDNA stability. G4 structures in mtDNA raise the question of their recognition by factors associated with the mitochondrial nucleoid. The mitochondrial transcription factor A (TFAM), a high-mobility group (HMG)-box protein, is the major binding protein of human mtDNA and plays a critical role in its expression and maintenance. HMG-box proteins are pleiotropic sensors of DNA structural alterations. Thus, we investigated and uncovered a surprising ability of TFAM to bind to DNA or RNA G4 with great versatility, showing an affinity similar than to double-stranded DNA. The recognition of G4s by endogenous TFAM was detected in mitochondrial extracts by pull-down experiments using a G4-DNA from the mtDNA conserved sequence block II (CSBII). Biochemical characterization shows that TFAM binding to G4 depends on both the G-quartets core and flanking single-stranded overhangs. Additionally, it shows a structure-specific binding mode that differs from B-DNA, including G4-dependent TFAM multimerization. These TFAM-G4 interactions suggest functional recognition of G4s in the mitochondria.
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lyonnais
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Aleix
authors.initials: A
authors.lastname: Tarrés-Solé
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Rubio-Cosials
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Cuppari
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Reicy
authors.initials: R
authors.lastname: Brito
authors.affiliation: Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Barcelona, 08028, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Jaumot
authors.affiliation: Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Barcelona, 08028, Spain.
authors.forename: Raimundo
authors.initials: R
authors.lastname: Gargallo
authors.affiliation: Mass Spectrometry Core Facility, Institute for Research in Biomedicine, IRB Barcelona, 08028 Barcelona, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Vilaseca
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Silva
authors.affiliation: CNRS UMR9187, INSERM U1196, Institut Curie, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Anton
authors.initials: A
authors.lastname: Granzhan
authors.affiliation: CNRS UMR9187, INSERM U1196, Institut Curie, Université Paris-Sud, 91405 Orsay, France.
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Teulade-Fichou
authors.affiliation: IQAC-CSIC, CIBER-BBN, Barcelona, E-08034, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Eritja
authors.affiliation: Structural MitoLab, Structural Biology Unit, Molecular Biology Institute of Barcelona (CSIC), Barcelona, 08028, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Solà
mesh_terms: D004247:DNA / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D054856:G-Quadruplexes; D006367:HeLa Cells; D006801:Humans; D024101:Mitochondrial Proteins / Q000378:metabolism*; D011485:Protein Binding; D012313:RNA / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D004272:DNA, Mitochondrial; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C499631:TFAM protein, human; D014157:Transcription Factors; D012313:RNA; D004247:DNA