A02: A novel membrane-bound phospholipase B of Pseudomonas aeruginosa

The Gram-negative human pathogen Pseudomonas aeruginosa causes a wide range of infections with severe morbidity and mortality cases. Among many virulence factors produced by P. aeruginosa are several phospholipases generally known to contribute to nutrient utilization, phospholipid homeostasis, damage of host cell membranes and modulation of lipid signaling in eukaryotic cells. Here, we will study PlbF, a newly identified phospholipase B linked to biofilm formation and virulence of P. aeruginosa. The enzyme is anchored to the cytoplasmic membrane via a single transmembrane (TM) helix which is involved in the formation of homodimers. Recently, we solved the PlbF crystal structure which revealed a unique dimerisation mode through coiled-coil interactions of TM helices. In the crystal structure, fatty acid ligands bound in the active site were identified which may represent lipid messengers and could thus provide a link to virulence properties of P. aeruginosa. In this project, we aim to determine how the dynamics of mono- to dimerisation regulates the catalytic properties of PlbF. We furthermore want to elucidate the physiological role of PlbF for lipid signaling which becomes increasingly relevant for bacterial communication within and between cells, in particular during bacterial infections.

Figure 1: PlbF is a monotopic homodimer in the crystal structure. Dimerization occurs through interaction of TM helices (in blue). The phospholipase domain of PlbF (in green) harboring the active site residues Ser137, His258 and Asp286 (shown as black, yellow and red sticks) is localised in the periplasm. The ?-helical do-mains presumably interacting with the membrane are colored in magenta. Hexanoic (C6), decanoic (C10) and tetradecenoic (C14) fatty acids (carbon atoms: orange, oxygen atoms: red) and one molecule of ?-octyl-glucoside (?-OG) were identified in the crystal structure. The bacterial cytoplasmic membrane is indicated as a grey area.

Project leader:
Prof. Dr. Karl-Erich Jaeger, undefined email,
                        undefinedInstitute of Molecular Enzyme Technology

Associated leader: Dr. Filip Kovacic, undefined email

Researchers: Christoph Strunk, undefined email
                      Muttalip Caliskan, undefined email
                      Andrea Weiler, undefined email

Responsible for the content: E-MailRedaktionsteam SFB 1208