title: The Drosophila telomere-capping protein Verrocchio binds single-stranded DNA and protects telomeres from DNA damage response.
abstract: Drosophila telomeres are sequence-independent structures maintained by transposition to chromosome ends of three specialized retroelements rather than by telomerase activity. Fly telomeres are protected by the terminin complex that includes the HOAP, HipHop, Moi and Ver proteins. These are fast evolving, non-conserved proteins that localize and function exclusively at telomeres, protecting them from fusion events. We have previously suggested that terminin is the functional analogue of shelterin, the multi-protein complex that protects human telomeres. Here, we use electrophoretic mobility shift assay (EMSA) and atomic force microscopy (AFM) to show that Ver preferentially binds single-stranded DNA (ssDNA) with no sequence specificity. We also show that Moi and Ver form a complex in vivo. Although these two proteins are mutually dependent for their localization at telomeres, Moi neither binds ssDNA nor facilitates Ver binding to ssDNA. Consistent with these results, we found that Ver-depleted telomeres form RPA and γH2AX foci, like the human telomeres lacking the ssDNA-binding POT1 protein. Collectively, our findings suggest that Drosophila telomeres possess a ssDNA overhang like the other eukaryotes, and that the terminin complex is architecturally and functionally similar to shelterin.
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Cicconi
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Micheli
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.
authors.forename: Fiammetta
authors.initials: F
authors.lastname: Vernì
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
authors.forename: Alison
authors.initials: A
authors.lastname: Jackson
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
authors.forename: Ana Citlali
authors.initials: AC
authors.lastname: Gradilla
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.|Centro Fermi, Piazza del Viminale 1, 00184 Roma, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Cipressa
authors.affiliation: Dipartimento di Medicina Molecolare, Sapienza, Università di Roma, 00185 Roma, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Raimondo
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Bosso
authors.affiliation: Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
authors.forename: James G
authors.initials: JG
authors.lastname: Wakefield
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Ciapponi
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cenci
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, 00185 Roma, Italy.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Gatti
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Cacchione
authors.affiliation: Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.|Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
authors.forename: Grazia Daniela
authors.initials: GD
authors.lastname: Raffa
mesh_terms: D000818:Animals; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology; D004249:DNA Damage; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000378:metabolism* / Q000648:ultrastructure; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D018625:Microscopy, Atomic Force; D000072417:Protein Domains; D055503:Protein Multimerization; D051716:Replication Protein A / Q000378:metabolism; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004277:DNA, Single-Stranded; D029721:Drosophila Proteins; D051716:Replication Protein A; C497166:RpA-70 protein, Drosophila; D034501:Telomere-Binding Proteins; C551478:Ver protein, Drosophila; C539342:moi protein, Drosophila