AN ALTERNATIVE TOPOLOGICAL MODEL FOR ESCHERICHIA-COLI OMPA

The current topological model for the Escherichia coli outer membrane protein OmpA predicts eight N-terminal trans membrane segments followe d by a long periplasmic tail. Several recent reports have raised serio us doubts about the accuracy of this prediction. An alternative OmpA m odel has been constructed using (1) computer-aided predictions develop ed specifically to predict topology of bacterial outer membrane porins , (2) the results of two reports that identified sequence homologies b etween OmpA and other peptidoglycan-associated proteins, and (3) bioch emical, immunochemical, and genetic topological data on proteins of th e OmpA family provided by numerous previous studies. The new model not only agrees with the varied experimental data concerning OmpA but als o provides an improved understanding of the relationship between the s tructure and the multifunctional role of OmpA in the bacterial outer m embrane.