Nitric oxide (NO) is one among many stimuli that can trigger biofilm formation. Biofilms are complex communities of bacteria on solid surfaces. In Shewanella woodyi, a biofilm-dwelling marine bacterium, we have determined the molecular basis for NO-regulated biofilm formation. We have shown that NO is sensed by an NO sensor H-NOX protein. NO-bound H-NOX regulates the enzymatic activity of an associated diguanylate cyclase/phosphodiesterase protein (DGC), thus regulating cyclic di-GMP synthesis in response to NO. C-di-GMP is well known to trigger biofilm formation. The goal of the research presented here is to determine the molecular architecture of the H-NOX/DGC complex. DGC is a very large, multi-domain protein (80 KDa) with two different enzymatic active sites. In a reductionist approach, we are synthesizing various single or multi-domain truncations of DGC and using these pieces to determine domain-domain interactions and domain functions. Using this approach, we have shown that H-NOX directly interacts with DGC via the PAS domain of DGC. Data supporting this conclusion as well as other intra- and inter-domain interactions in the H-NOX/DGC system will be presented.

Molecular insights into H-NOX and DGC signaling leading to biofilm formation in Shewanella woodyi

243rd National Meeting (2012)

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