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It's a NO for Bacterial Settlement: Nitric Oxide Regulated Biofilm Formation and Protein Expression

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dc.contributor.advisor Boon, Elizabeth M en_US
dc.contributor.author Xu, Yueming en_US
dc.contributor.other Department of Chemistry en_US
dc.date.accessioned 2017-09-20T16:52:08Z
dc.date.available 2017-09-20T16:52:08Z
dc.date.issued 2015-08-01 en_US
dc.identifier.uri http://hdl.handle.net/11401/77169 en_US
dc.description 128 pgs en_US
dc.description.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 <italic>Vibrio harveyi</italic>, 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 <italic>Shewanella woodyi</italic>, H-NOX binds a bifunctional DGC (SwHaCE). Nanomolar levels of NO repress biofilm formation through c-di-GMP degradation, and enhance phosphodiesterase activity of <italic>Sw</italic>HaCE, leading to c-di-GMP hydrolysis. H-NOX regulation is not limited to iv proteins in the same operon. <italic>Sw</italic>H-NOX can also interact with <italic>Vh</italic>HqsK homologue, <italic>Sw</italic>HK (Swoo_2833). Weaker biofilm phenotype in response to NO is attenuated when SwHK gene is disrupted in <italic>S. woodyi</italic>. 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. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Chemistry en_US
dc.title It's a NO for Bacterial Settlement: Nitric Oxide Regulated Biofilm Formation and Protein Expression en_US
dc.type Dissertation en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Tonge, Peter en_US
dc.contributor.committeemember Schärer, Orlando en_US
dc.contributor.committeemember Walker, Stephen en_US


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