LasB

lasB, or elastase B, is a gene encoding elastase B, a secreted zinc-dependent metalloprotease produced by the bacterium Pseudomonas aeruginosa. It is one of the principal extracellular proteases of this organism and belongs to the thermolysin-like family of metalloproteases (M4). The enzyme is synthesized as a preproenzyme with a propeptide and is exported to the extracellular milieu via the type II secretion system, where it is activated by removal of the propeptide.

LasB has a broad substrate range and contributes to virulence by degrading host structural proteins such as elastin, collagen, and laminin, as well as extracellular matrix components. It also cleaves immune and host defense molecules, including immunoglobulins and complement components, and can modulate coagulation factors. Through these activities, LasB disrupts epithelial barriers, facilitates tissue invasion, and can alter inflammatory responses, thereby promoting infection in environments such as the cystic fibrosis lung and chronic wounds.

Regulation of lasB expression is closely tied to the Las quorum-sensing network, primarily the LasI/LasR system, and it is coordinated with other virulence factors like LasA. Expression responds to growth phase and environmental cues, contributing to the pathogen’s ability to adapt during infection.

Clinical and research relevance centers on its role as a major virulence determinant and a target for interventions. Inhibitors that chelate the active-site zinc or otherwise block metalloprotease activity can suppress LasB function in experimental settings, highlighting potential therapeutic approaches, though clinical application is complicated by redundancy in virulence pathways.