Acinetobacter baumannii Regulates Bacterial Motility Through PilZ-containing Proteins

Authors' Affiliations

Garrett Reynolds, Department of Biological Sciences, College of Arts and Science, Vanderbilt University, Nashville, TN.

Location

D.P. Culp Center Ballroom

Start Date

4-5-2024 9:00 AM

End Date

4-5-2024 11:30 AM

Poster Number

106

Name of Project's Faculty Sponsor

Erik Petersen

Faculty Sponsor's Department

Health Sciences

Classification of First Author

Graduate Student-Master’s

Competition Type

Competitive

Type

Poster Presentation

Presentation Category

Health

Abstract or Artist's Statement

Acinetobacter baumannii is an emerging nosocomial pathogen that has acquired multi-drug resistance in remarkable time and positioned itself at the forefront of concern for healthcare professionals and researchers alike. This multi-drug resistance in combination with its unprecedented ability to survive desiccation on surfaces help illustrate how and why A. baumannii has become such a formidable pathogen. Another key mechanism that A. baumannii and numerous other bacteria have at their disposal when it comes to infections, spreading, and navigating their environment is motility. While A. baumannii lacks flagella used to swim in liquids, it encodes type IV pili that can be used in twitching motility along semisolid substrates. Some A. baumannii strains use these pili to move across the top of agar surfaces, while other strains require a solid, plastic surface in which to crawl across. The machinery used to power, extend, and retract these type IV pili is tightly regulated in response to changing environmental cues. In particular, the bacterial second messenger cyclic-di-GMP is often used to regulate transitions between being sessile and motile. In other bacteria, this regulation can use PilZ domains that appear in numerous proteins and tend to bind cyclic-di-GMP. We used bioinformatic tools to identify two PilZ-containing proteins within A. baumannii. Deletion of either of these two PilZ domain-containing proteins severely inhibited surface-associated motility, while at least one is required for movement along a plastic surface. Notably, one of these proteins appears to be a homolog of the PilZ protein for which the domain is named. This protein has been demonstrated to play a role in regulating motility in other bacteria. Interestingly, although cyclic-di-GMP appears to regulate this motility, preliminary analysis of cyclic-di-GMP binding by our PilZ-containing proteins using a fluorescent biosensor suggests neither protein may bind cyclic-di-GMP. While there is precedent for this in scientific literature, further testing will be required to determine whether this is the case. Future work using mutants of these proteins will help to determine how they participate in the regulation of pilus-mediated motility in A. baumannii.

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Apr 5th, 9:00 AM Apr 5th, 11:30 AM

Acinetobacter baumannii Regulates Bacterial Motility Through PilZ-containing Proteins

D.P. Culp Center Ballroom

Acinetobacter baumannii is an emerging nosocomial pathogen that has acquired multi-drug resistance in remarkable time and positioned itself at the forefront of concern for healthcare professionals and researchers alike. This multi-drug resistance in combination with its unprecedented ability to survive desiccation on surfaces help illustrate how and why A. baumannii has become such a formidable pathogen. Another key mechanism that A. baumannii and numerous other bacteria have at their disposal when it comes to infections, spreading, and navigating their environment is motility. While A. baumannii lacks flagella used to swim in liquids, it encodes type IV pili that can be used in twitching motility along semisolid substrates. Some A. baumannii strains use these pili to move across the top of agar surfaces, while other strains require a solid, plastic surface in which to crawl across. The machinery used to power, extend, and retract these type IV pili is tightly regulated in response to changing environmental cues. In particular, the bacterial second messenger cyclic-di-GMP is often used to regulate transitions between being sessile and motile. In other bacteria, this regulation can use PilZ domains that appear in numerous proteins and tend to bind cyclic-di-GMP. We used bioinformatic tools to identify two PilZ-containing proteins within A. baumannii. Deletion of either of these two PilZ domain-containing proteins severely inhibited surface-associated motility, while at least one is required for movement along a plastic surface. Notably, one of these proteins appears to be a homolog of the PilZ protein for which the domain is named. This protein has been demonstrated to play a role in regulating motility in other bacteria. Interestingly, although cyclic-di-GMP appears to regulate this motility, preliminary analysis of cyclic-di-GMP binding by our PilZ-containing proteins using a fluorescent biosensor suggests neither protein may bind cyclic-di-GMP. While there is precedent for this in scientific literature, further testing will be required to determine whether this is the case. Future work using mutants of these proteins will help to determine how they participate in the regulation of pilus-mediated motility in A. baumannii.