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Nucleic Acids Res. 2017 Apr 7;45(6):3068-3085. doi: 10.1093/nar/gkw1244.

The Drosophila telomere-capping protein Verrocchio binds single-stranded DNA and protects telomeres from DNA damage response.

Author information

1
Dipartimento di Biologia e Biotecnologie 'C. Darwin', Sapienza, Università di Roma, 00185 Roma, Italy.
2
Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy.
3
Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.
4
Centro Fermi, Piazza del Viminale 1, 00184 Roma, Italy.
5
Dipartimento di Medicina Molecolare, Sapienza, Università di Roma, 00185 Roma, Italy.
6
Istituto di Biologia e Patologia Molecolari (IBPM) del CNR, 00185 Roma, Italy.

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.

PMID:
27940556
PMCID:
PMC5389638
DOI:
10.1093/nar/gkw1244
[Indexed for MEDLINE]
Free PMC Article

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