Abstract
Mannose-sensitive hemagglutinin (MSHA) pili and flagellum are critical for the surface attachment of Vibrio cholerae, the first step of V. cholerae colonization on host surfaces. However, the cell landing mechanism remains largely unknown, particularly in viscoelastic environments such as the mucus layers of intestines. Here, combining the cysteine-substitution-based labeling method with single-cell tracking techniques, we quantitatively characterized the landing of V. cholerae by directly observing both pili and flagellum of cells in a viscoelastic non-Newtonian solution consisting of 2% Luria-Bertani and 1% methylcellulose (LB+MC). The results show that MSHA pili are evenly distributed along the cell length and can stick to surfaces at any point along the filament. With such properties, MSHA pili are observed to act as a brake and anchor during cell landing which includes three phases: running, lingering, and attaching. Importantly, loss of MSHA pili results in a more dramatic increase in mean path length in LB+MC than in 2% LB only or in 20% Ficoll solutions, indicating that the role of MSHA pili during cell landing is more apparent in viscoelastic non-Newtonian fluids than viscous Newtonian ones. Our work provides a detailed picture of the landing dynamics of V. cholerae under viscoelastic conditions, which can provide insights into ways to better control V. cholerae infections in a real mucus-like environment.
Highlights
Vibrio cholerae, a human pathogen that causes the debilitating disease cholera, is a natural inhabitant of aquatic ecosystems (Almagro-Moreno et al, 2015; Kaper et al, 1995)
Our work provides a detailed picture of the landing dynamics of V. cholerae under viscoelastic conditions, during which, the synergistic functions of Mannose-sensitive hemagglutinin (MSHA) pili and flagellum are elucidated
MSHA pili are evenly distributed along cell length with a constant length density To visualize the MSHA pili, we constructed a mutant (MshAT70C) by cysteine substitution, which can subsequently be labeled with highly specific maleimide dyes (Figure 1a and Figure 1—figure supplement 1), following the protocol in Ellison et al, 2019; Ellison et al, 2017
Summary
A human pathogen that causes the debilitating disease cholera, is a natural inhabitant of aquatic ecosystems (Almagro-Moreno et al, 2015; Kaper et al, 1995) They can form biofilms on both biotic and abiotic surfaces, which increase their infectivity and environmental survival (Donlan and Costerton, 2002; Silva and Benitez, 2016; Teschler et al, 2015; Yildiz and Visick, 2009). Bacterial appendages have been shown to play important roles in regulating bacterial activities, especially biofilm formation during microbe-host interactions. The flagellum is required for biofilm formation in a variety of bacteria species, such as Escherichia coli (Pratt and Kolter, 1998), Pseudomonas aeruginosa (O’Toole and Kolter, 1998), and V. cholerae (Guttenplan and Kearns, 2013; Watnick and Kolter, 1999). Type IV pili (TFP) are another type of filamentous appendages commonly found on many bacteria and
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