Type
Text
Type
Dissertation
Advisor
Boon, Elizabeth M | Tonge, Peter | Schärer, Orlando | Walker, Stephen.
Date
2015-08-01
Keywords
Chemistry
Department
Department of Chemistry.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/77169
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Nitric Oxide (NO) is a diatomic signaling molecule that regulates diverse bacterial behaviors. Its effect on cell motility has been established in many microbial systems, but the molecular mechanism remains understudied. Some bacteria have an H-NOX (Heme-Nitric oxide/OXygen-binding) domain that functions as an NO sensor. It is found in the same operon with two component signaling histidine kinases or diguanylate cyclases (DGC) that synthesize and degrade cyclic di-GMP (c-di-GMP). C-di-GMP is a secondary signaling molecule that regulates bacterial motile to sessile lifestyle transition. In this dissertation, we dedicated our effort toward understanding the effect on bacterial biofilm by NO/H-NOX regulated signaling pathway. In Vibrio harveyi, NO mediates quorum sensing (QS) through the H-NOX/HqsK pathway. We show that NO regulates flagellar production and biofilm formation in a concentration dependent manner. At low nanomolar concentration of NO, repression of flagellin coincides with enhanced biofilm. As NO concentration increases (100~200nM), a global switch takes place in protein expression and results in decreased flagellar production and less promotion of biofilm. In Shewanella woodyi, H-NOX binds a bifunctional DGC (SwHaCE). Nanomolar levels of NO repress biofilm formation through c-di-GMP degradation, and enhance phosphodiesterase activity of SwHaCE, leading to c-di-GMP hydrolysis. H-NOX regulation is not limited to iv proteins in the same operon. SwH-NOX can also interact with VhHqsK homologue, SwHK (Swoo_2833). Weaker biofilm phenotype in response to NO is attenuated when SwHK gene is disrupted in S. woodyi. In summary, NO mediates biofilm formation and protein expression via binding sensor protein H-NOX in multiple systems. Since biofilm is the predominant form of bacteria in natural aquatic environment, revealing the NO signaling mechanism would facilitate further understanding of bacterial group behavior. | 128 pages
Recommended Citation
Xu, Yueming, "It's a NO for Bacterial Settlement: Nitric Oxide Regulated Biofilm Formation and Protein Expression" (2015). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 3004.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/3004