CRUCIAL DOMAINS ARE CONSERVED IN ENTEROBACTERIACEAE PORINS

With the recent resolution of the crystal structures of several bacter ial porins, it is worthwhile to define the generality of their organiz ation throughout the Enterobacteriaceae. The distribution of specific epitopes was analysed among various Gram-negative bacterial porins usi ng anti-peptide antibodies specific to exposed, transmembrane spanning , or pore-forming regions of Escherichia coli porins. Anti-peptide ant ibodies which recognized the exposed epitopes indicated a great variab ility among the bacterial porins analysed. Interestingly, an antigenic site located in the internal loop L3 constricting the pore diameter w as present in the majority of the bacterial porins tested. Two epitope s located in domains involved in subunit interaction were also highly conserved. The presence of these common peptides suggested a conservat ion of specific regions involved in the functional organization of the enterobacterial porins.