Looking at proteins from different angles: The unusual behavior of phospholipase PlaB from Legionella pneumophila

Presented by: Wulf Blankenfeldt, Ph.D., Helmholtz-Zentrum für Infektionsforschung
Presented Live: February 22, 2022

Legionella pneumophila, the causative agent of Legionnaires’ Disease, uses contaminated freshwater to trigger potentially fatal pneumonia. It enters lung macrophages and establishes itself in a protected niche by secreting a plethora of proteins into the host cell. Among these factors is a significant number of phospholipases that damage host cell membranes, manipulate signal transduction by interfering with second messengers and provide nutrients to the bacterium. One of these phospholipases is PlaB, a PLA2-type phospholipase that inserts into the outer membrane of L. pneumophila after being secreted via an unknown pathway. Interestingly, PlaB shows lowest specific activity at high protein concentrations, which is the consequence of tetramer formation and may represent a means of self-protection that prevents harmful activity while PlaB is synthesized within the L. pneumophila cell.

A surprising mechanism that controls the tetramerization of PlaB was discovered by employing different analytical methods, including SEC-MALS and protein crystallography in prominent roles. These findings demonstrate the synergy of looking at proteins from different angles.