TOLA CENTRAL DOMAIN INTERACTS WITH ESCHERICHIA-COLI PORINS

TolA is an inner membrane protein with three domains: a transmembrane N-terminus and periplasmic central and C-terminal domains. The interac tion of TolA with outer membrane porins of Escherichia coli was invest igated. Western blot analyses of cell extracts with anti-TolA antibodi es indicated that TolA forms high molecular weight complexes specifica lly with trimeric OmpF, OmpC, PhoE and LamB, but not with OmpA. The in teraction of purified TolA domains with purified porins was also studi ed. TolA interacted with OmpF, PhoE and LamB porins via its central do main, but not with either their denatured monomeric forms or OmpA. Mor eover, the presence or absence of lipopolysaccharides associated with trimeric porins did not modify the interactions. These results suggest that the specific interaction of TolA with outer membrane porins migh t be relevant to the function of Tol proteins.