Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

National Institute of Environmental Health Sciences

Use this QR code to view the newest version of this document
Use this QR code to view the newest version of this document

Your Environment. Your Health.

Publication Detail

Title: Structure, dynamics, and regulation of TRF1-TIN2-mediated trans- and cis-interactions on telomeric DNA.

Authors: Pan, Hai; Kaur, Parminder; Barnes, Ryan; Detwiler, Ariana C; Sanford, Samantha Lynn; Liu, Ming; Xu, Pengning; Mahn, Chelsea; Tang, Qingyu; Hao, Pengyu; Bhattaram, Dhruv; You, Changjiang; Gu, Xinyun; Lu, Warren; Piehler, Jacob; Xu, Guozhou; Weninger, Keith; Riehn, Robert; Opresko, Patricia L; Wang, Hong

Published In J Biol Chem, (2021 Sep)

Abstract: TIN2 is a core component of the shelterin complex linking double-stranded telomeric DNA-binding proteins (TRF1 and TRF2) and single-strand overhang-binding proteins (TPP1-POT1). In vivo, the large majority of TRF1 and TRF2 exist in complexes containing TIN2 but lacking TPP1/POT1; however, the role of TRF1-TIN2 interactions in mediating interactions with telomeric DNA is unclear. Here, we investigated DNA molecular structures promoted by TRF1-TIN2 interaction using atomic force microscopy (AFM), total internal reflection fluorescence microscopy (TIRFM), and the DNA tightrope assay. We demonstrate that the short (TIN2S) and long (TIN2L) isoforms of TIN2 facilitate TRF1-mediated DNA compaction (cis-interactions) and DNA-DNA bridging (trans-interactions) in a telomeric sequence- and length-dependent manner. On the short telomeric DNA substrate (six TTAGGG repeats), the majority of TRF1-mediated telomeric DNA-DNA bridging events are transient with a lifetime of ~1.95 s. On longer DNA substrates (270 TTAGGG repeats), TIN2 forms multiprotein complexes with TRF1 and stabilizes TRF1-mediated DNA-DNA bridging events that last on the order of minutes. Preincubation of TRF1 with its regulator protein Tankyrase 1 and the cofactor NAD+ significantly reduced TRF1-TIN2 mediated DNA-DNA bridging, whereas TIN2 protected the disassembly of TRF1-TIN2 mediated DNA-DNA bridging upon Tankyrase 1 addition. Furthermore, we showed that TPP1 inhibits TRF1-TIN2L-mediated DNA-DNA bridging. Our study, together with previous findings, supports a molecular model in which protein assemblies at telomeres are heterogeneous with distinct subcomplexes and full shelterin complexes playing distinct roles in telomere protection and elongation.

PubMed ID: 34403696 Exiting the NIEHS site

MeSH Terms: Cell Adhesion Molecules/metabolism*; Cell Adhesion Molecules/physiology; DNA-Binding Proteins/metabolism; DNA/metabolism; Humans; Microscopy, Atomic Force/methods; Models, Molecular; Multiprotein Complexes/metabolism; Protein Binding; Protein Isoforms/metabolism; Shelterin Complex/metabolism; Shelterin Complex/physiology; Telomere-Binding Proteins/metabolism*; Telomere-Binding Proteins/physiology; Telomere/metabolism; Telomeric Repeat Binding Protein 1/metabolism; Telomeric Repeat Binding Protein 1/physiology; Telomeric Repeat Binding Protein 2/metabolism*; Telomeric Repeat Binding Protein 2/physiology

Back
to Top