Pseudomonas aeruginosa exhibits directed twitching motility up phosphatidylethanolamine gradients

Pseudomonas aeruginosa translocates over solid surfaces by a type IV pilus- dependent form of multicellular motility known as twitching. We wondered wh ether cells utilize endogenous factors to organize twitching, and we purifi ed from wild-type cells a lipid that caused directed movement. Wild-type P. aeruginosa, but not a pill pilus-deficient mutant, showed biased movement up gradients of phosphatidylethanolamine (PE) established in agar. Activity was related to the fatty acid composition of the lipid, as two synthetic P E species, dilauroyl and dioleoyl PE, were capable of directing P, aerugino sa motility while many other species were inactive. P. aeruginosa PE did no t contain either laurate or oleate, implying that the native attractant spe cies contains different fatty acids. Uniform concentrations of PE increased cell velocity, suggesting that chemokinesis may be at least partly respons ible for directed movement. We speculate that PE-directed twitching motilit y may be involved in biofilm formation and pathogenesis.