Biophysical Society Thematic Meeting | Ascona 2026

Mechanobiology of Infection

Monday Speaker Abstracts

BACTERIALLY-INFECTED MACROPHAGES PROMOTE BIOMECHANICAL ALTERATIONS IN ENDOTHELIAL CELL MONOLAYERS FOR TRANSMIGRATION Effie Bastounis Humboldt University of Berlin, Germany

No Abstract

EXPERIMENTAL EVOLUTION REVEALS DISTINCT FLAGELLAR STRATEGIES FOR ENHANCED MOTILITY IN COMPLEX ENVIRONMENTS Seiga Yanagisawa 1,2 ; Wayne D Frasch 3 ; Navish Wadhwa 1,2,4 ; 1 Arizona State University, Biodesign Center for Mechanisms of Evolution, Tempe, AZ, USA 2 Arizona State University, Center for Biological Physics, Tempe, AZ, USA 3 Arizona State University, School of Life Sciences, Tempe, AZ, USA 4 Arizona State University, Department of Physics, Tempe, AZ, USA Bacterial pathogens must navigate the complex, viscous environments of host tissues to establish infection, yet how bacteria tune their flagellar machinery to optimize motility in such environments remains an open question. Using experimental evolution, we show that E. coli rapidly evolves enhanced motility in structured media through two distinct strategies: increasing flagella number and altering the shape of the flagellar filament. Strikingly, these changes do not always translate to faster swimming in liquid, revealing that motility in structured environments is mechanistically distinct from swimming in bulk fluid. By tracing this altered filament shape to a single point mutation in the flagellin protein FliC, we identify a structural switch within FliC that controls the shape of the filament and, consequently, how well bacteria move through structured environments. These findings reveal how the physical properties of the environment shape the evolution of flagellar function, with implications for understanding how pathogens navigate host tissues during infection.

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