Spectral properties of three quaternary arrangements of Pseudomonas pilin

Abstract

P. aeruginosa possess multisubunit, filamentous appendages called pili which are involved in adhesion, twitching motility and phage adsorption. The spectral properties of 3 forms of pili were compared. These are native pili, pilin dimers in octyl glycoside and an in vitro assembled form of pilin which called reassembled pilin filaments. Alkaline pH titrations, solvent perturbation, quenching of tryptophan fluorescence with acrylamide and circular dichroism were used to demonstrate that tyrosines-24 and -27 are at a dimer/dimer interface in native pili and in the reassembled pilin filaments. Dissociation of pili by octyl glucoside results in exposure of the 2 tyrosines and in partial exposure of at least 1 tryptophan in pilin.