THE OPRB PORIN PLAYS A CENTRAL ROLE IN CARBOHYDRATE UPTAKE IN PSEUDOMONAS-AERUGINOSA

Using interposon mutagenesis, we have generated strains of Pseudomonas aeruginosa which lack or overexpress the substrate-selective OprB por in of this species. A marked decrease or increase in the initial uptak e of glucose by these strains verified the role of OprB in facilitatin g the diffusion of glucose across the outer membrane of P. aeruginosa. However, we also demonstrated that the loss or overexpression of OprB had a similar effect on the uptake of three other sugars able to supp ort the growth of this bacterium (mannitol, glycerol, and fructose). T his effect was restricted to carbohydrate transport; arginine uptake w as identical in mutant and wild-type strains. These results indicated that OprB cannot be considered strictly a glucose-selective porin; rat her, it acts as a central component of carbohydrate transport and is m ore accurately described as a carbohydrate-selective porin.