Collaborative Research: Telomerase Structure and Evolution in Photosynthetic Eukaryotes

Project: Research project

Project Details


Telomerase is an essential ribonucleoprotein reverse transcriptase complex that ensures genome integrity by continually replenishing the terminal DNA sequences that would otherwise be lost during conventional DNA replication. The integral long noncoding RNA subunit, TR, varies dramatically in size, sequence and secondary structure across eukaryotic kingdoms. Although TR has been characterized in several major lineages, the origins and evolutionary connections among TRs, their protein binding partners and their modes of transcription and RNP assembly remain largely unresolved. The remarkable diversity of telomerase makes it an outstanding model system for elucidating the evolution of and transition between protein and RNP enzymes. In 2019 the two PIs, Julian Chen (ASU) and Dorothy Shippen (TAMU) initiated a highly productive collaboration resulting in identification of the bona-fide TR from Arabidopsis and a robust and informative secondary structure model for plant TRs, which revealed that plant TR is an evolutionary bridge uniting the highly disparate TRs from ciliates and humans. For this collaborative NSF application, the Shippen and Chen labs expand their fruitful collaboration and leverage the complementary strengths of their teams to explore structure and evolution of plant telomerases.
For Objective 1 the Shippen lab proposes mass spectrometry to identify the full subunit composition of Arabidopsis telomerase, including ancillary proteins that may be involved in telomerase regulation. A second goal is to obtain a 3D structure for the core RNP using cryo-EM. For Objective 2 the Chen lab proposes a comparative analysis of early telomerase evolution across plastid-containing photosynthetic and non-photosynthetic algae by identifying TRs in the Archaeplastida and Chromista kingdoms. Telomerase RNP composition and biogenesis will be studied in select algal model organisms from both kingdoms for new insights into the evolution and origin of telomerase. For Objective 3 the Shippen and Chen labs join forces to examine the role of dyskerin in plant telomerases. Human TR is transcribed by RNA Pol II and is bound by dyskerin via a conserved H/ACA motif. Plant TRs, however, are transcribed by RNA Pol III and lack the canonical H/ACA motif, and yet still engage dyskerin. The molecular basis and biological function of dyskerin in telomerase from Arabidopsis and early emerging algae will be examined.
Intellectual Merit: This research seeks to fill a large knowledge gap presented by the highly divergent structures of ciliate and vertebrate telomerase enzymes. Moreover, by revealing the full subunit composition and architecture of plant telomerase, novel accessory factors and new modes of RNA-protein interaction may be uncovered. In addition, by expanding telomerase analysis beyond land plants to the basal branching photosynthetic eukaryotes there is a unique opportunity to reveal preserved ancestral features and attributes connecting the telomerase RNPs from single-celled eukaryotes, plants and animals. More broadly, comprehensive analysis of telomerase RNP structure, function and evolution across the entire eukaryotic domain will help to establish fundamental rules underlying the biomolecular transition from RNA to RNP to protein enzymes during the evolution of life on Earth.
Broader Impacts: The PIs are international leaders in telomerase biochemistry. Dr. Shippen pioneered the area of plant telomere biology, while Dr. Chen has made seminal contributions in telomerase RNA evolution. Dr. Shippen has been nationally recognized for mentorship and as part of this study, she will present workshops to graduate students and postdocs at ASU and TAMU on the fundamentals of Scientific Leadership and the Art of Negotiation. Both labs are committed to undergraduate student training. Dr. Chen currently curates the Telomerase Database, which is a useful training tool for undergraduates in literature searches and data curation. To broaden the impact of telomerase research, undergraduate and high school students will be recruited and trained to improve the database by adding stories and animations describing the discovery, expansion and impact of telomere/telomerase research. To leverage the complementary strengths of the two research programs and enhance synergy in discovery, the Shippen and Chen labs will hold monthly cross-university virtual group meetings and an annual day-long telomerase mini-symposium that will feature research talks from each lab, including short presentations by undergraduates. In addition, one member from each team will travel to the other site each year to receive training on crucial technologies/protocols.
Effective start/end date2/15/211/31/25


  • National Science Foundation (NSF): $749,999.00