# Structural dynamics of progesterone receptor-coactivator complexes

> **NIH NIH R01** · UNIVERSITY OF FLORIDA · 2024 · $578,099

## Abstract

Summary: Steroid hormones receptors (SR) are ligand-dependent nuclear transcription factors that exhibit
remarkable functional diversity in mediating cell/tissue and target gene specific responses, largely driven by
conformational dynamics of the SR protein that enables it's binding of unique subsets of transcriptional co-
regulatory proteins (CoRs) and DNA response elements. The progesterone receptor (PR) is the main target of
progestogens that are widely used clinically. PR is expressed as two protein isoforms, an N-terminal truncated
PR-A and full-length PR-B and each have distinct physiological roles dependent on the cell/tissue type. In general
PR-A is a weaker transcriptional activator than PR-B, and can act to attenuate the activity of PR-B. Both isoforms
are typically co-expressed in equal proportions in most normal tissues. However, PR-A to PR-B ratios have been
reported to be highly variable in pathological conditions. Mechanistic basis for differences in activity of the
isoforms is not well defined but is generally believed to be due to unknown differences in structural
conformations. Thus, to fully understand PRs' biology requires determination of a high-resolution structure of the
full-length PR isoforms and associated CoRs as a complex on target DNA and an understanding of how protein
interactions within the complex and structural conformations affect activity of PR. The conformational flexibility
of SRs and CoRs, coupled and their large sizes (100–300 MW), make them unsuitable to either high resolution
NMR or X-ray crystallography analysis. As an alternative, this proposal will integrate complementary solution-
phase techniques to determine high-resolution 3D structural models and uncover the conformational dynamics
within the PR:CoR/DNA complex. Recent advances in Cryo-EM enable the determination of solution-phase
structures of large conformationally heterogenous macromolecular complexes at subnanometer resolution. We
will combine Cryo-EM with crosslinking mass spectrometry (XL-MS) to further refine structural Cryo-EM models
and assure high resolution and with hydrogen-deuterium exchange (HDX) to map conformational dynamics and
allostery within the PR:CoR/DNA complex. The overall goal of this project is to determine the highest resolution
3D structure possible of full-length PR-A and PR-B in complex with classical CoRs and novel CoRs on PR DNA
response elements. Aim 1 will utilize Cryo-EM to analyze the structural features of PR-A and PR-B in complex
with the classical CoRs SRC3 and p300 and with the novel CoRs TBP and JDP2 assembled on target DNA.
Aim 2 will refine the Cryo-EM structure of PR:CoR/DNA complex using integrated structural modeling and XL-
MS to define distance constraints and probe conformational dynamics within the PR complex by differential HDX.
Aim 3 will perform functional mutagenesis studies to determine the influence of PR:SRC3/p300 interaction
surfaces revealed in structural models and from XL-MS data have on...

## Key facts

- **NIH application ID:** 10831022
- **Project number:** 5R01CA263574-03
- **Recipient organization:** UNIVERSITY OF FLORIDA
- **Principal Investigator:** Dean P Edwards
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $578,099
- **Award type:** 5
- **Project period:** 2022-05-24 → 2027-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10831022

## Citation

> US National Institutes of Health, RePORTER application 10831022, Structural dynamics of progesterone receptor-coactivator complexes (5R01CA263574-03). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10831022. Licensed CC0.

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