Evidence for association of lipopolysaccharide with Pseudomonas fluorescens strain MF0 porin OprF

Lipopolysaccharide (LPS) was found to be associated with the major outer membrane protein OprF of the psychrotrophic bacterium Pseudomonas fluorescens MFO, using two OprF purification procedures. OprF, purified under mild conditions, presented two types of association with LPS: tight (tLPS) and slight (sLPS), both of type R. LPS protected OprF from heat modification and trypsin degradation and facilitated the reincorporation of purified OprF into an artificial lipid bilayer without affecting its pore-forming activity. The size of the OprF channel depended on cell, growth temperature, as did the extent of LPS phosphorylation: we suggest that LPS may be involved in modifications of OprF pore formation. (C) 2000 Editions scientifiques et medicales Elsevier SAS.