TERRA G-quadruplex RNA interaction with TRF2 GAR domain is required for telomere integrity

Abstract

Telomere dysfunction causes chromosomal instability which is associated with many cancers and age-related diseases. The non-coding telomeric repeat-containing RNA (TERRA) forms a structural and regulatory component of the telomere that is implicated in telomere maintenance and chromosomal end protection. The basic N-terminal Gly/Arg-rich (GAR) domain of telomeric repeat-binding factor 2 (TRF2) can bind TERRA but the structural basis and significance of this interaction remains poorly understood. Here, we show that TRF2 GAR recognizes G-quadruplex features of TERRA. We show that small molecules that disrupt the TERRA-TRF2 GAR complex, such as N-methyl mesoporphyrin IX (NMM) or genetic deletion of TRF2 GAR domain, result in the loss of TERRA, and the induction of γH2AX-associated telomeric DNA damage associated with decreased telomere length, and increased telomere aberrations, including telomere fragility. Taken together, our data indicates that the G-quadruplex structure of TERRA is an important recognition element for TRF2 GAR domain and this interaction between TRF2 GAR and TERRA is essential to maintain telomere stability.

Keeping Balance Between Genetic Stability and Plasticity at the Telomere and Subtelomere of Trypanosoma brucei

“…In addition, TbTRF exhibits a slightly stronger affinity to the duplex telomere DNA than TERRA in in vitro competition binding assays (Saha et al, 2021). Therefore, the telomere DNA binding and TERRA-binding activities of TbTRF may have overlapping nucleic acid interaction interfaces, which is clearly different from how human TRF 2 binds TERRA and telomere DNA (Bilaud et al, 1997;Broccoli et al, 1997b;Deng et al, 2009b;Mei et al, 2021).…”

“…Overexpression of an ectopic allele of RNaseH1 in the TbRAP1depleted cells suppresses the increased amount of telomeric R-loop and DNA damage and the increased VSG switching frequency phenotypes, while the TERRA level in these cells is still higher than that in WT cells (Nanavaty et al, 2017). Therefore, the function of TbRAP1 in maintaining telomere/subtelomere Suppresses NHEJ-mediated chromosome end-to-end fusions van Steensel et al, 1998;Karlseder et al, 1999;Celli and de Lange, 2005 Suppresses telomere HR Wang et al, 2004 Suppresses telomerase-mediated telomere elongation Smogorzewska et al, 2000 Promotes telomeric R-loop formation Lee et al, 2018 Facilitates the T-loop structure formation and maintenance Doksani et al, 2013;Timashev and de Lange, 2020 Suppresses trans-localization of TERRA Feretzaki et al, 2020 The GAR domain is essential for binding TERRA Deng et al, 2009b;Mei et al, 2021 integrity relies on its repressive effects on TERRA and telomeric R-loop. The TERRA molecules in TbRAP1-depleted cells are much longer than that in WT cells (Nanavaty et al, 2017), suggesting that TbRAP1 can block the transcription elongation of RNA Polymerase I along the telomere by associating with the telomere chromatin.…”

“…Depletion of human TRF2 also results in an increased level of TERRA (Porro et al, 2014b). In addition, TRF2 binds TERRA predominantly through its N-terminal GAR domain (Deng et al, 2009b;Mei et al, 2021; Figure 2). TbTRF also has a TERRA binding activity, which surprisingly resides in its Myb domain (Saha et al, 2021).…”

Regulation of Antigenic Variation by Trypanosoma brucei Telomere Proteins Depends on Their Unique DNA Binding Activities

“…Human TRF2 is also capable of binding TERRA and suppresses its level [ 226 ]. However, TRF2 uses its N-terminal basic GAR domain to bind TERRA [ 226 , 227 ] and TRF2 also promotes the TRL formation [ 228 ]. In contrast, Tb TRF suppresses the TRL level, and most interestingly, Tb TRF binds TERRA through its Myb domain [ 75 ].…”

Selective Binding and Redox-Activity on Parallel G-Quadruplexes by Pegylated Naphthalene Diimide-Copper Complexes

“…As examples, 5′-UTR mRNA-G4s have been recognized as regulators of gene translational processes [ 8 ] and multimeric mRNA-G4s are proven sequestering RNA-binding proteins impairing their functions [ 9 ]. Moreover, telomeric repeat-containing RNAs folded into G4s (TERRA) are involved in numerous processes, including the regulation of telomerase functioning [ 10 ], as well as the regulation of viral activity which can be affected by RNA-G4s folding [ 11 ].…”