Biogenesis and evolution of fungal telomerase RNA

Project: Research project

Description

Overview:
Telomerase is one of the most divergent ribonucleoprotein (RNP) enzymes known to date; making it an excellent model for the fundamental study of RNP evolution and function. RNP enzymes are a unique group of enzymes that require both protein and RNA subunits for vital cellular functions. The essential core of telomerase RNP consists of a catalytic telomerase reverse transcriptase (TERT) protein subunit and a TERT-interacting long non-coding RNA (lncRNA), knowed as telomerase RNA (TR), that provides a template for DNA synthesis and also confers telomerase enzymatic activity. While a short region of TR serves as template for telomeric DNA synthesis, the vastly larger remainder of the RNA is composed of several structural and functional domains essential for RNP assembly, enzymatic activity, and binding of accessory proteins. Surprisingly, TRs from diverse eukaryotic groups differ dramatically in transcriptional machinery, accessory protein composition, and biogenesis pathway. So far, TR has been identified and studied virtually exclusively in vertebrates, yeasts, ciliates and plants. Each of these groups of species employ disparate and distinct pathways for TR processing and accumulation. TRs from vertebrates are bound by the dyskerin protein complex, and share a biogenesis pathway with small nucleolar RNAs (snoRNAs). In contrast, yeast, TRs are bound by the Sm-protein complex, and share a biogenesis pathway with small nuclear RNAs (snRNAs). The origin and evolutionary connections among TRs from different groups of species remain unresolved. Recently, we discovered that Neurosproa crassa TR employs a novel biogenesis pathway that is independent of the Sm-protein complex and distinct from that of yeast TR pathway. Exploring the unique mechanism of TR biogenesis in N. crassa and early diverging fungi will expand our understanding of telomerase biogenesis and evolution among fungi, as well as identify novel mechanism for RNA maturation.
The two specific objectives are to (1) determine the unique biogenesis pathway of N. crassa TR and (2) elucidate the origin and evolution of distinct fungal TR biogenesis pathways. The first objective will be accomplished by identifying regions in the N. crassa TR that are essential for processing and accumulation, and identifying the associated accessory proteins responsible for these functions. The second objective requires the identification of TRs from early branching fungi, Basidiomycetes, Zygomycetes and Chytridiomycetes, as well as a choanoflagellate Monosiga brevicollis, the closest relative of metazoa and fungi. For this, we will employ our well-established next-generation sequencing-based methodology for TR identification. This will provide crucial insights into telomerase RNP evolution and diversity within the fungal lineage. In addition, our proposed research activities will involve training of high school, undergraduate and graduate students for producing the next generation of scientific researchers.
Intellectual merit: One of the most prevalent and challenging questions surrounding telomerase is the underlying cause and mechanism for the extensive divergence in TR size, sequence, secondary structure and biogenesis pathway. To address this outstanding question, telomerase from diverse representative taxa within eukaryotes must be studied. However, the very nature of TR sequence diversity generates challenges that continue to be a major obstacle for TR identification from taxa beyond the previously explored groups of species. This research program will employ our novel, yet proven, approaches for identifying and characterizing TRs from key fungal species outside of the Ascomycota phylum. The newly identified TRs will offer novel, exciting models for telomerase RNP structure-function and biogenesis studies. Collectively, the results from this project will provide new insights into the molecular evolution of fungal telomerase RNP structure-function, and expand our knowledge of the diversity of lncRNA biogenesis pathways.
Broader impact: Scientific impact: Telomerase is crucial for maintaining chromosome stability and cellular immortality. Elucidating the novel biogenesis pathway of N. crassa telomerase RNP and understanding the evolution of telomerase biogenesis from unexplored fungal groups will shed light into the functional co-evolution of the RNA and protein components of an RNP enzyme. The methodology developed in this research program is directly applicable to other RNPs. Moreover, many fungal species to be studied in this project are pathogens of amphibians and crops. Understanding the structure and function of telomerase enzymes from these fungal species will have significant impact on ecology and agriculture. Educational impact: This project will closely involve the training of high school and undergraduate students from underrepresented minority groups. This will offer laboratory training to first-generation college students, which aims to motivate and encourage students to pursue careers in the STEM disciplines. Moreover, this research experience will improve their applications and competitiveness for graduate school in STEM disciplines. Students will also participate in updating and improving our Telomerase Database, which serves as an effective means of disseminating hypothesis- and curiosity-driven research to the general public. Keyword: Ribonucleoprotein; RNA structure; telomerase biogenesis; molecular evolution; chromosome; telomere; DNA replication; RNA-protein interactions; phylogenetic analysis.
StatusActive
Effective start/end date8/1/167/31/20

Funding

  • NSF: Directorate for Biological Sciences (BIO): $610,000.00

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Fungal RNA
Telomerase
Ribonucleoproteins
RNA
Students
Fungi
Long Noncoding RNA
Proteins
Enzymes
telomerase RNA
Scanning Transmission Electron Microscopy
Research
Molecular Evolution
Yeasts
Protein Subunits
Vertebrates
Choanoflagellata