Molecular mechanisms of biofilm dispersal in Pseudomonas aeruginosa
Biofilms are microbial communities that adhere to surfaces and grow into multicellular macrocolonies. In biofilms, tThe cells are embedded in the biofilm in a polymer matrix, which protects the cells from environmental stress. Therefore, biofilms are very persistent and of high medical and industrial relevance for medicine and industry. The formation of a biofilm takes place in several stages. At the end of the biofilm life cycle, biofilm dispersal takes place. Part of the cells detach from the biofilm matrix and become planktonic. This enables the cells to spread and colonise new surfaces. At the molecular level, biofilm dissolution in various bacteria correlates with changes in the cellular concentration of the secondary messenger c-di-GMP (bis-(3'-5')-cyclic di-guanosine monophosphate). Various signals, e.g. nutrient deficiency, stimulate c-di-GMP-degrading phosphodiesterases, resulting in a decrease of the intracellular c-di-GMP level. Low c-di-GMP concentrations lead to biofilm dispersal.
In this project we investigate the membrane protein NbdA from Pseudomonas aeruginosa and its function in biofilm dispersal. The protein NbdA is a multidomain protein with the domain sequence MHYT-AGDEF-EAL, which and has a proven phosphodiesterase activity. Based on bioinformatic analyses, a sensor function for diatomic gases was postulated for the membrane-anchored MHYT domain.
The protein and different variants are heterologously produced and biochemically characterized. The focus is on the enzymatic activity and the analysis of the membrane domain. In order to understand the molecular mechanisms of biofilm dispersal, reporter gene fusions will be used to investigate how the transcription of nbdA is regulated. Phenotypic investigations and interaction analyses will clarify the integration of NbdA into the complex process of biofilm dissolution. Many phosphodiesterases have a strongly limited spatial function. Confocal fluorescence microscopy is used to analyze the localization of NbdA in planktonic cells and in biofilms.