ABSTRACT
The topological model of the Enterobacter cloacae outer membrane protein OmpX showed three putative glycosylation sites. When OmpX was expressed in bacteria that were cultured under aerated conditions, no glycosylation was observed. The coupling of carbohydrate chains to the ompX gene product was also investigated in the eukaryotic baculovirus expression system. For this purpose, a recombinant ompX gene-containing baculovirus was made. Infection of insect cells with this recombinant virus resulted in the production of sufficient amounts of OmpX to study glycosylation. In this system, all potential N-glycosylation sites of OmpX were utilized. Furthermore, it became clear that glycosylated OmpX was retained in the insect cells and was not secreted in the medium. Given the fact that OmpX plays a role in the invasion of E. cloacae in rabbit enterocytes, glycosylation of this protein occurring only under specific conditions may be involved in this process.