Isolation and characterization of a porin-like outer membrane protein from Xanthomonas campestris pv. campestris

Xanthomonas campestris pv. campestris, a plant-associated pathogenic bacterium, is the causal agent of foliar spots and blights in crucifers. The major outer membrane protein, Omp37, of 37 kDa, has been identified, purified to homogeneity, and its characterization has also been carried out. Native Omp37 behaved as a trimer, as revealed by gel filtration and SDS-PAGE. FTIR measurements revealed a high beta-structure content. The pore-forming ability of the purified Omp37 was studied by the liposome swelling assay. Omp37, to our knowledge, is the first porin that has been isolated from Xanthomonas. This study clearly demonstrates that Omp37 is related to the family of trimeric bacterial porins.