# Identification of Protein-Protein Interactions and Processing Events That Traffic and Activate the Bactericidal Pore-Forming Protein Perforin-2

> **NIH NIH R21** · UNIVERSITY OF MIAMI SCHOOL OF MEDICINE · 2021 · $191,875

## Abstract

The destruction of microorganisms within phagolysosomes is an essential immunological function of
macrophages and other phagocytes that protects us from invading pathogens. Over the past several
years we have established that Perforin-2 (PRF2), a recently described effector of the innate immune
system, is pivotal for the destruction of phagocytosed bacteria. For example, we have published
studies demonstrating that PRF2 knockout mice succumb to infectious doses that the majority of their
wild-type littermates survive when challenged with bacterial pathogens. This is accompanied by
replication and dissemination of bacteria to deeper tissues. With cell based studies we established
bacteria that would normally be destroyed are able to replicate and persist within macrophages that
lack PRF2. It has also recently been shown that polymorphisms within human PRF2 increase an
individual's susceptibility to persistent nontuberculous mycobacterial infections. Most recently the
results of our collaboration with structural biologists were published demonstrating that PRF2
polymerizes to form rings of 16 subunits. This study also revealed that the transition from pre-pore to
pore is dependent upon low pH; such as would be encountered within acidifying phagosomes. Thus,
our investigations spanning from the atomic to experimental mice have established that PRF2
underpins an essential function of macrophages as a pore-forming protein that permeabilizes the
envelope of phagocytosed bacteria. Our working HYPOTHESIS is that PRF2-dependent killing of
bacteria is a multistep process that begins with the intracellular trafficking of PRF2 as an inactive
transmembrane (TM) protein in response to exogenous stimuli such as infection or pathogen-
associated molecular patterns. Subsequent cleavage of PRF2 from its TM domain releases it to
polymerize as a pre-pore structure on the membrane of phagocytosed bacteria. Acidification of the
maturing phagosome triggers a dramatic reorganization of PRF2 that culminates in membrane
penetrating pores through which other antimicrobials pass. Within this overall hypothesis are two
areas of uncertainty –trafficking and proteolytic processing– that are appropriate for exploratory
investigations. To redress these gaps Aim 1 will identify the protein-protein interactions that drive the
intracellular trafficking of PRF2. Aim 2 will characterize the proteolytic processing events that regulate
the activation of PRF2 within phagocytes. Significant impacts of this study will include a more
complete understanding of macrophage mediated killing of phagocytosed bacteria and the molecular
events that govern bactericidal pore formation.

## Key facts

- **NIH application ID:** 10195288
- **Project number:** 1R21AI159794-01
- **Recipient organization:** UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
- **Principal Investigator:** GEORGE Patrick MUNSON
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $191,875
- **Award type:** 1
- **Project period:** 2021-02-18 → 2023-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10195288

## Citation

> US National Institutes of Health, RePORTER application 10195288, Identification of Protein-Protein Interactions and Processing Events That Traffic and Activate the Bactericidal Pore-Forming Protein Perforin-2 (1R21AI159794-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10195288. Licensed CC0.

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