# Molecular Mechanisms of Bacterial Toxins Targeting the Actin Cytoskeleton

> **NIH NIH R01** · OHIO STATE UNIVERSITY · 2024 · $348,826

## Abstract

With the climate change-related emergence of new pathogens and the reemergence of old, once-controlled
pathogens, as well as in light of rapidly developing antibiotic resistance, society is in urgent need of a more
thorough understanding of the bacterial pathogenicity and its major mediators – toxins and toxic effector proteins
(effectors). The actin cytoskeleton is a common target for numerous bacterial effectors. However, the
mechanisms by which many actin-targeting bacterial toxins exhibit their pathogenicity remain poorly understood.
The long-term goal of the proposal is to decipher the in-depth molecular and cellular mechanisms of bacterial
effectors targeting the actin cytoskeleton to i) enable alternative ways of targeting pathogens and ii) get a deeper
understanding of the actin cytoskeleton per se. The current proposal is directly relevant to the NIH mission as it
focuses on three families of bacterial effectors, all produced by human pathogens. Furthermore, the proposal is
of interest for a general understanding of human physiology as each of the above toxins reveals novel properties
of the actin cytoskeleton. Thus, Aim 1 focuses on deciphering the novel hitherto unprecedented ability of VopF
and VopL effectors produced by Vibrio cholerae and Vibrio parahaemolyticus to potentiate actin processive
polymerization at the pointed ends. Aim 2 addresses the properties of SipA, an effector from Salmonella enterica
that exerts a novel mode of binding to actin, bestowing the pathogen an ability to adhere to and invade the
polarized host cell. In Aim 3, the proposal will decipher the mechanisms of actin-dependent membrane
remodeling by Legionella pneumophila effectors. Understanding these and related processes is particularly
important given that all intracellular pathogens depend heavily on hijacking host membrane organization to
survive and thrive inside the affected cell. The research strategy for the toxin characterization will be based on
using several highly complementary experimental approaches. The effects of the toxins on actin dynamics in
bulk and at the single-filament level will be combined with cell biology and structural biology approaches.
Specifically, bulk actin dynamics will be monitored via modifications of the pyrene-actin polymerization approach.
The effects of the toxins on the actin dynamics at the single-filament level will be characterized by total internal
reflection fluorescence microscopy, which will be enforced by microfluidics (in collaboration with Dr. Shekhar) for
deciphering the mechanisms employed by VopF/VopL toxins (Aim 1). A modification of this technique will be
used to decipher the mechanisms of a membrane-reorganizing protein MavH (Aim 3). The structures of VopF
with the actin pointed end (Aim1), and SipA bound along the filament side (Aim 2) will be characterized by the
cryoEM reconstruction in collaboration with Dr. Egelman’s group. Fluorescence anisotropy will be used to
describe the strengths of the int...

## Key facts

- **NIH application ID:** 10881349
- **Project number:** 2R01GM114666-10
- **Recipient organization:** OHIO STATE UNIVERSITY
- **Principal Investigator:** Dmitri Kudryashov
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $348,826
- **Award type:** 2
- **Project period:** 2015-09-01 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10881349

## Citation

> US National Institutes of Health, RePORTER application 10881349, Molecular Mechanisms of Bacterial Toxins Targeting the Actin Cytoskeleton (2R01GM114666-10). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/10881349. Licensed CC0.

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