A family of tubular pili from harmful algal bloom forming cyanobacterium Microcystis aeruginosa

Cyanobacteria are vital photosynthetic prokaryotes, but some form harmful algal blooms (cyanoHABs) that disrupt ecosystems and produce toxins. The mechanisms by which these blooms form have yet to be fully understood, particularly the role of extracellular components. Here, we present a 2.4 Å cryo-EM structure of a pilus, termed the cyanobacterial tubular (CT) pilus, found in the cyanoHAB-forming Microcystis aeruginosa. The pilin exhibits a unique protein fold, forming a tubular pilus structure with tight, double-layer anti-parallel β-sheet interactions. We show that CT pili are essential for buoyancy by facilitating the formation of micro-colonies, which increases drag force and prevents sinking. The CT pilus surface is heavily glycosylated with ten monosaccharide modifications per pilin. Furthermore, CT pili can enrich microcystin, potentially enhancing cellular resilience, and co-localize with iron-enriched extracellular matrix components. Thus, we propose that this pilus plays an important role in the proliferation of cyanoHABs. This just discovered pilus family appears to be widely distributed across several cyanobacterial orders. Our structural and functional characterization of CT pili provide insights into cyanobacterial cell morphology, physiology, and toxin interactions, and identify potential targets for disrupting bloom formation.

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Publication Details

Journal
Nature Communications
Published
2025-08-29
DOI
https://doi.org/10.1038/s41467-025-63379-1
Primary Topic
Aquatic Ecosystems and Phytoplankton Dynamics
Type
article
Field-Weighted Citation Impact
0.00

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article

A family of tubular pili from harmful algal bloom forming cyanobacterium Microcystis aeruginosa

Holly A. Petersen, Bobby G. Duersch, Adam Grosvirt-Dramen, J. William Louda et al.
Nature Communications
Aquatic Ecosystems and Phytoplankton Dynamics
article

A family of tubular pili from harmful algal bloom forming cyanobacterium Microcystis aeruginosa

Holly A. Petersen, Bobby G. Duersch, Adam Grosvirt-Dramen, J. William Louda, Craig Dufresne, Peter Weber, John G. Ricca, Ravi R. Sonani, Sarah Naylon, Xavier Mayali, Fengbin Wang, Peter E. Prevelige, Vivian M. Merk, Allon I. Hochbaum
article en

Abstract

Cyanobacteria are vital photosynthetic prokaryotes, but some form harmful algal blooms (cyanoHABs) that disrupt ecosystems and produce toxins. The mechanisms by which these blooms form have yet to be fully understood, particularly the role of extracellular components. Here, we present a 2.4 Å cryo-EM structure of a pilus, termed the cyanobacterial tubular (CT) pilus, found in the cyanoHAB-forming Microcystis aeruginosa. The pilin exhibits a unique protein fold, forming a tubular pilus structure with tight, double-layer anti-parallel β-sheet interactions. We show that CT pili are essential for buoyancy by facilitating the formation of micro-colonies, which increases drag force and prevents sinking. The CT pilus surface is heavily glycosylated with ten monosaccharide modifications per pilin. Furthermore, CT pili can enrich microcystin, potentially enhancing cellular resilience, and co-localize with iron-enriched extracellular matrix components. Thus, we propose that this pilus plays an important role in the proliferation of cyanoHABs. This just discovered pilus family appears to be widely distributed across several cyanobacterial orders. Our structural and functional characterization of CT pili provide insights into cyanobacterial cell morphology, physiology, and toxin interactions, and identify potential targets for disrupting bloom formation.

Nature CommunicationsVol. 16(1)
Lawrence Livermore National Laboratory (US), University of California, Irvine (US), University of Utah (US), University of Alabama at Birmingham (US), Irvine University (US), Thermo Fisher Scientific (United States) (US), University of Virginia (US), Florida Atlantic University (US), Université de Strasbourg (FR)
U.S. Department of Defense, U.S. Department of Energy, South Florida Water Management District, Frederick National Laboratory for Cancer Research, National Institutes of Health, U.S. Geological Survey, National Cancer Institute, Lawrence Livermore National Laboratory
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Openalex Percentile: Top 81%
Aquatic Ecosystems and Phytoplankton Dynamics
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