Characterization of the NspS-MbaA signaling system controlling biofilm formation from polyamine input to phenotypic output

ASU Author/Contributor (non-ASU co-authors, if there are any, appear on document)
Richard Sobe (Creator)
Institution
Appalachian State University (ASU )
Web Site: https://library.appstate.edu/
Advisor
Ece Karatan

Abstract: Biofilm formation plays a critical role in the infectious cycle of the bacterial pathogen, Vibrio cholerae. The polyamine, norspermidine, has a positive influence on biofilm formation while spermidine has the opposite effect. These influences occur through a signaling system comprised of the periplasmic polyamine binding protein, NspS, and the transmembrane phosphodiesterase, MbaA. In the absence of NspS, MbaA acts as a phosphodiesterase cleaving the pro-biofilm second messenger, cyclic di-GMP, indicating that NspS may interact with and inhibit phosphodiesterase activity and biofilm repression by MbaA. In this study, I have shown that several nspS ligand-binding pocket mutants have altered sensitivity to norspermidine and spermidine as indicated by vps transcription and biofilm assays. I have also shown using thermal shift assays that these mutants are capable of binding both polyamines. LC-MS/MS analyses indicate that the NspS-MbaA signaling pathway is a high specificity c-di-GMP signaling system. Additionally, a system for reproducible demonstration of the NspS-MbaA interaction was developed which may subsequently be used in future experiments to study the NspS and MbaA interaction. Altogether, this study provides a thorough investigation of the steps involved in polyamine signal input to phenotypic output for a novel polyamine responsive signaling system controlling V. cholerae biofilm formation.

Additional Information

Publication
Thesis
Sobe, R (2015) Characterization of the NspS-MbaA signaling system controlling biofilm formation from polyamine input to phenotypic output. Unpublished master's thesis. Appalachian State University, Boone, NC
Language: English
Date: 2015
Keywords
Vibrio-cholerae, Biofilm-formation, Polyamine Signaling-system, NspS and MbaA

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