Pseudomonas aeruginosa is a ubiquitous bacterium that can adapt to very different environmental conditions. It is found in surface waters, in soil, and as an opportunistic human pathogen. The formation of biofilms from P. aeruginosa is of particular importance. Cyclic diguanylate (c-di-GMP) is a central messenger for the regulation of biofilm formation. The activity of the phosphodiesterase NbdA from P. aeruginosa influences the concentration of this messenger molecule in the cell. The protein consists of three conserved domains, an as yet uncharacterized membrane-bound MHYT domain, a degenerated diguanylate cyclase domain and a phosphodiesterase domain. The phosphodiesterase domain is responsible for the cleavage of c-di-GMP to the linear dinucleotide pGpG. The activity has been demonstrated both in vivo and in vitro. The diguanylate cyclase domain showed no activity. The function of the membrane-bound MHYT domain is still poorly understood. We suspect a role in signal perception and regulation of the enzymatic subdomains. In our research group, we want to understand the function of the protein, especially the membrane domain MHYT, and what role it plays in the cell.

To understand the physiological role of this protein we study gene regulation (transcription and translation analysis) and the localization of the protein in vivo (confocal microscopy). In addition, we study protein-protein interactions to identify interaction partners of NbdA (two hybrid and pull down assays).

For the characterization of the membrane protein, we established the purification of NbdA as a recombinant protein from E. coli. In addition, protein variants were generated by mutagenesis and targeted truncation. We use spectroscopic, biochemical and biophysical methods to characterize the full-length protein and protein variants in more detail.