Structural Basis of Lipid Targeting and Destruction by the Type V Secretion System of Pseudomonas aeruginosa.

The type V secretion system is a macromolecular machine employed by a number of bacteria to secrete virulence factors into the environment. The human pathogen Pseudomonas aeruginosa employs the newly described type Vd secretion system to secrete a soluble variant of PlpD, a lipase of the patatin-like family synthesized as a single macromolecule that also carries a polypeptide transport-associated domain and a 16-stranded β-barrel. Here we report the crystal structure of the secreted form of PlpD in its biologically active state.

Protein secretion systems in Pseudomonas aeruginosa: A wealth of pathogenic weapons.

Pathogenic microorganisms have to face hostile environments while colonizing and infecting their hosts. Unfortunately, they can cope with it and have evolved a number of complex secretion systems, which direct virulence factors either at the bacterial cell surface into the environmental extracellular milieu or into the host cell cytosol. Six different classes of secretion systems have been described so far, currently identified as type I secretion system (T1SS) up to type VI secretion system (T6SS).

The Pseudomonas aeruginosa patatin-like protein PlpD is the archetype of a novel Type V secretion system.

We discovered a novel secreted protein by Pseudomonas aeruginosa, PlpD, as a member of the bacterial lipolytic enzyme family of patatin-like proteins (PLPs). PlpD is synthesized as a single molecule consisting of a secreted domain fused to a transporter domain. The N-terminus of PlpD includes a classical signal peptide followed by the four PLP conserved blocks that account for its lipase activity.