# Photosystem II as a model protein for understanding metalloenzyme active site assembly

> **NIH NIH R00** · UNIVERSITY OF WISCONSIN-MADISON · 2024 · $248,999

## Abstract

Project Summary
Metalloenzymes are ubiquitous throughout biology and implicated in a variety of human diseases. A gap in our
understanding of metalloenzymes lies in their maturation. Biogenesis intermediates precede formation of the
mature enzyme and must be tightly regulated to correctly assemble the metallocofactor in the active site. Despite
the wealth of knowledge on mature metalloenzymes, their biogenesis, especially active site assembly, is not well
understood. Photosystem II (PSII) is a light-driven oxidoreductase whose active site contains a metallocofactor
that is assembled through a series of step-wise ion binding and photooxidation events called photoactivation.
Photoactivation provides a convenient model for understanding metallocofactor assembly because it is facile; in
vitro assembly may be achieved by simply adding the required ions in solution and assembly is advanced by
providing light quanta. Furthermore, recent advances in structural investigation of PSII have developed a
platform for routinely solving high-resolution structures of PSII assembly intermediates. We propose to
characterize biogenesis intermediates of PSII that may reveal generalized rules for metalloenzyme assembly.
The long-term goals of this project are to provide structural and functional bases for assembly of the
metallocofactor in PSII (training phase), and reveal how PSII biogenesis intermediates maintain precursor
structures important for active site maintenance (independent phase). We will use structural approaches,
biochemical techniques, and computational modeling to achieve the following three specific objectives: (1) to
reveal how the oxygen evolving complex of PSII is assembled, (2) to uncover precursor structures of PSII that
are integral for assembling its active site, and (3) to understand the role of transiently-bound subunits during PSII
biogenesis. Gaining such insight may allow for the development of new therapeutics and design principles for
de novo metalloenzyme engineering.

## Key facts

- **NIH application ID:** 11138858
- **Project number:** 4R00GM140174-03
- **Recipient organization:** UNIVERSITY OF WISCONSIN-MADISON
- **Principal Investigator:** Christopher Gisriel
- **Activity code:** R00 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $248,999
- **Award type:** 4N
- **Project period:** 2021-09-01 → 2027-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/11138858

## Citation

> US National Institutes of Health, RePORTER application 11138858, Photosystem II as a model protein for understanding metalloenzyme active site assembly (4R00GM140174-03). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/11138858. Licensed CC0.

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