Conserved, unstructured regions in Pseudomonas aeruginosa PilO are important for type IVa pilus function

Pseudomonas aeruginosa uses long, thin fibres called type IV pili (T4P) for adherence to surfaces, biofilm formation, and twitching motility. A conserved subcomplex of PilMNOP is required for extension and retraction of T4P. To better understand its function, we attempted to co-crystallize the soluble periplasmic portions of PilNOP, using reductive surface methylation to promote crystal formation. Only PilOΔ109 crystallized; its structure was …