# Mechanism of cytoskeletal transport and transcription-coupled DNA repair

> **NIH NIH R35** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2022 · $630,134

## Abstract

PROJECT SUMMARY
Cells must organize their contents spatially and temporally. The microtubule cytoskeleton and its associated
molecular motors, dynein and kinesin, are the main system used by cells to move cargos, ranging from protein
assemblies to entire organelles, including the nucleus. Dynein (~0.5MDa) is a member of the AAA+ family. Active
dynein complexes, the only ones capable of transporting cargo, are ~4MDa and consist of two dynein dimers
bound to the ~1.0MDa dynactin complex, and an adaptor protein that links them to cargo. Lis1, another
essential regulator of dynein, is necessary for their formation. Previously, we showed how Lis1 regulates
dynein’s mechanochemistry. Here, we will focus on understanding how the 90kDa Lis1 dimer helps activate
and assemble the 4MDa transport complex.
 Chromatin, with the nucleosome as its basic unit, provides both a solution to the problem of packaging
the genome, and a tool to regulate access to it. Among the factors involved in controlling chromatin dynamics
are ATP-dependent nucleosome remodelers, which couple ATP hydrolysis to the non-covalent modification of
nucleosome structure. Both remodelers and the modifications they catalyze are very diverse, even though all
remodelers use the same mechanism, and conserved catalytic core, to break histone-DNA contacts. I am
interested in how this common underlying mechanism is modulated to result in the wide array of
outcomes of which remodelers are capable. Previously, we focused on model systems representing two of
the four families of “canonical” remodelers. Here, we will focus on Rad26 (the yeast ortholog of CSB), an “orphan”
remodeler that uses its remodeling-like activity to act on RNA Pol II to help it overcome obstacles or initiate
Transcription Coupled DNA Repair (TCR) when the obstacle is a DNA lesion. We aim to understand how
Rad26 helps RNA Pol II recognize a lesion from other obstacles and recruit downstream repair factors.
 We take a structure-guided approach to addressing fundamental mechanistic questions, with cryo-
electron microscopy (cryo-EM) as our main technique. We use the structures we generate to formulate
mechanistic hypotheses that can be tested, either in house or in collaboration, using a range of techniques
including single-molecule biophysics, biochemistry, and cell biology. We have made major contributions to our
understanding of the mechanochemical cycle of dynein and its regulation, and to the functional diversity and
regulation of nucleosome remodelers. We are also interested in developing tools to solve challenges we
encounter along the cryo-EM pipeline and have made important contributions to cryo-EM grid preparation and
data processing in the cloud. We are currently developing approaches to increase the efficiency of data
collection.

## Key facts

- **NIH application ID:** 10405228
- **Project number:** 1R35GM145296-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Andres E Leschziner
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $630,134
- **Award type:** 1
- **Project period:** 2022-08-01 → 2027-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10405228

## Citation

> US National Institutes of Health, RePORTER application 10405228, Mechanism of cytoskeletal transport and transcription-coupled DNA repair (1R35GM145296-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10405228. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*