MTV, an ssDNA Protecting Complex Essential for Transposon-Based Telomere Maintenance in Drosophila

PLoS Genet. 2016 Nov 11;12(11):e1006435. doi: 10.1371/journal.pgen.1006435. eCollection 2016 Nov.

Abstract

Multiple complexes protect telomeres. In telomerase-maintained organisms, Shelterin related complexes occupy the duplex region while the CST and Tpp1-Pot1 complexes bind the single stranded overhang of telomeres. Drosophila uses a transposon-based mechanism for end protection. We showed that the HOAP-HipHop complex occupies the duplex region. Whether an ssDNA-binding complex exists is not known. Here we discover a novel protein, Tea, that is specifically enriched at telomeres to prevent telomere fusion. We also identify a complex consisting of Tea and two known capping proteins, Ver and Moi. The Moi-Tea-Ver (MTV) complex purified in vitro binds and protects ssDNA in a sequence-independent manner. Tea recruits Ver and Moi to telomeres, and point mutations disrupting MTV interaction in vitro result in telomere uncapping, consistent with these proteins functioning as a complex in vivo. MTV thus shares functional similarities with CST or TPP1-POT1 in protecting ssDNA, highlighting a conserved feature in end protecting mechanisms.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Chromosomal Proteins, Non-Histone / genetics*
  • DNA Transposable Elements / genetics
  • DNA, Single-Stranded / genetics*
  • Drosophila Proteins / genetics*
  • Drosophila melanogaster / genetics
  • Nerve Growth Factors / genetics*
  • Point Mutation / genetics
  • Protein Binding / genetics
  • Protein Serine-Threonine Kinases / genetics
  • Telomerase / genetics
  • Telomere / genetics
  • Telomere Homeostasis / genetics*

Substances

  • Carrier Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA Transposable Elements
  • DNA, Single-Stranded
  • Drosophila Proteins
  • Nerve Growth Factors
  • Tea protein, Drosophila
  • moi protein, Drosophila
  • pot protein, Drosophila
  • sbb protein, Drosophila
  • Protein Serine-Threonine Kinases
  • Telomerase

Grants and funding

This work was supported by the intramural research program of the National Cancer Institute, USA and subsequently a grant from NSFC of China (Grant #31371364). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.