# Telomere terminal extension and replication: mechanisms and links to DNA repair

> **NIH NIH R01** · WEILL MEDICAL COLL OF CORNELL UNIV · 2021 · $390,470

## Abstract

Project Summary/Abstract
Telomeres, the specialized nucleoprotein structures located at the ends of eukaryotic chromosomes, are critical
for genome stability. Telomere DNA, which consists of numerous copies of a short repeat, is difficult to maintain
owing to (1) the end replication problem that prevents the complete duplication of parental DNA; and (2) the
propensity of telomere DNA and chromatin to form replication barriers. The main players that help to overcome
these difficulties include (1) telomerase, a special reverse transcriptase that adds “G-strand” repeats onto the 3’
ends of chromosomes; (2) primase-Pol a (PP), which adds “C-strand” repeats onto the 5’ ends of chromosomes;
and (3) helicases and repair proteins that facilitate semi-conservative replication through telomeres. Telomerase
has been subjected to detailed investigation and much is known about its mechanisms and regulation. Hence,
in this application, we will focus on the roles of primase-Pol a and repair proteins such as Rad51 and Brh2
(BRCA2). The study will employ two fungal models (Candida glabrata and Ustilago maydis), each with its own
unique advantages.
 In Aim 1, we will examine the mechanisms of PP and its regulation by CST, a telomere binding complex. We
have identified a critical and conserved interface between the Stn1 and Pol12 subunits of CST and PP, and
shown that this interaction likely triggers a conformational switch in PP to facilitate DNA synthesis. We will
address this novel conformational switch mechanism using a combination of biochemistry, cyroEM and smFRET.
In addition, both CST and PP have been linked to telomere replication and genome-wide replication stress
response, though the underlying mechanisms are poorly understood. Accordingly, we will dissect the role of the
CST-PP interaction in these pathways. These studies will be conducted using C. glabrata proteins because they
are easily purified and biochemically tractable. In Aim 2 – 3, we will address the mechanisms of two core repair
proteins (Rad51 and Brh2[BRCA2]) in telomere replication and telomere capping. we have developed a high-
resolution assay for telomere replication defects and used the assay to demonstrate critical functions for several
repair proteins. We have also uncovered a novel and conserved interaction between Rad51 the telomere protein
Pot1, which suggests novel, telomere-specific regulatory mechanisms. Hence in these two aims, we will dissect
the mechanisms of Rad51 at telomeres and determine how its functions are regulated by Pot1 and Brh2 using
a combination of genetics and biochemistry. Because RAD51 and BRCA2 factors have also been implicated in
promoting replication and stabilizing stalled forks throughout the genome, our work may lead to a more integrated
view of their mechanisms. This investigation will be carried out using Ustilago maydis because unlike standard
fungi, U. maydis exhibits a high degree of similarity to mammals with respect to the recombination and telo...

## Key facts

- **NIH application ID:** 10155499
- **Project number:** 5R01GM107287-06
- **Recipient organization:** WEILL MEDICAL COLL OF CORNELL UNIV
- **Principal Investigator:** NEAL F LUE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $390,470
- **Award type:** 5
- **Project period:** 2014-08-11 → 2024-02-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10155499

## Citation

> US National Institutes of Health, RePORTER application 10155499, Telomere terminal extension and replication: mechanisms and links to DNA repair (5R01GM107287-06). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10155499. Licensed CC0.

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