Identification and characterization of an outer membrane protein, OmpX, in @entity526 that is homologous to a family of outer membrane proteins including Ail of XXXX .

@entity2491 @entity1 @entity7100 @entity526 @entity2820
We previously reported that a region of the @entity526 chromosome at 18 min increased E sigma E activity when cloned in multicopy (J. Mecsas, P. E. Rouviere, J. W. Erickson, T. J. Donohue, and C. A. Gross, Genes Dev. 7:2618-2628, 1993). In the present report, we identify and characterize the gene responsible for the increase in E sigma E activity. This gene is in a monocistronic operon with two promoters and a rho-independent terminator. Sequence analysis of this gene indicated that it encodes an outer membrane protein which is 83% identical to OmpX in @entity7100 , leading us to name this gene ompX. There are four other proteins that are homologous to OmpX. Several of these proteins, Ail of @entity2820 and Rck and PagC of @entity2491 , have properties that allow bacteria to adhere to @entity1 cells, survive exposure to human serum, and/or survive within macrophages. We therefore characterized strains deleted for ompX for their growth phenotypes, E sigma E activity, serum resistance, and adherence to @entity1 cells. No differences in growth rates, serum resistance, or adherence to @entity1 cells were observed; however, E sigma E activity was dependent on expression of OmpX in certain strain backgrounds.
