Shear force impacts type IV pilus and flagellar dynamics during Pseudomonas aeruginosa surface adhesion

Palalay, Jessica-Jae S

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https://hdl.handle.net/2142/132470 Copy

Description

Title

Shear force impacts type IV pilus and flagellar dynamics during Pseudomonas aeruginosa surface adhesion

Author(s)

Palalay, Jessica-Jae S

Issue Date

2025-10-14

Director of Research (if dissertation) or Advisor (if thesis)

Sanfilippo, Joseph E

Doctoral Committee Chair(s)

Sanfilippo, Joseph E

Committee Member(s)

• Huang, Raven H
• Brieher, William M
• Mera, Paola E

Department of Study

Biochemistry

Discipline

Biochemistry

Degree Granting Institution

University of Illinois Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Microfluidics
• shear force
• adhesion
• Pseudomonas aeruginosa
• type IV pili
• flagella

Abstract

Surface-attached bacteria experience forces associated with fluid flow in nature. However, many studies on bacterial adhesion have been conducted in conditions either lacking flow or using forces not typically found in natural systems. In Chapter 2, I examine how Pseudomonas aeruginosa cells use type IV pili to interact with surfaces under host-relevant shear forces. I demonstrate that cell tilting, driven by type IV pilus retraction, predicts surface departure at low shear forces. Conversely, higher host-relevant shear forces counteract cell tilting and enhance adhesion. Thus, P. aeruginosa couples type IV pilus dynamics and cell geometry to tune adhesion to its mechanical environment. In Chapter 3, I investigate how host-relevant shear force impacts flagellar rotation during P. aeruginosa initial surface interactions. Experiments using strains having fluorescently-labeled flagella reveal that flow bends upstream-facing flagella and blocks rotation. Additionally, cells with upstream flagella exhibit fewer surface departures than cells with downstream flagella, showing that flagellar rotation drives surface departure. Therefore, these results reveal a novel role for flagellar rotation and determine how bacteria optimize surface interactions in dynamic environments. Together, these findings emphasize the need to study bacteria under mechanically relevant conditions. Shear force exerts a mechanical stress on surface attached bacterial cells, leading to prolonged surface adhesion. By integrating host-relevant conditions into bacterial research, my work has provided a clearer understanding of how P. aeruginosa optimizes surface behavior in dynamic environments.

Graduation Semester

2025-12

Type of Resource

Thesis

Handle URL

https://hdl.handle.net/2142/132470

Copyright and License Information

Copyright 2025 Jessica-Jae Palalay

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