Overexpression of the Bam Complex Improves the Production of <i>Chlamydia trachomatis</i> MOMP in the <i>E. coli</i> Outer Membrane

Abstract

A licensed Chlamydia trachomatis (Ct) vaccine is not yet available. Recombinant Chlamydia trachomatis major outer membrane protein (Ct-MOMP), the most abundant constituent of the chlamydial outer membrane complex, is considered the most attractive candidate for subunit-based vaccine formulations. Unfortunately, Ct-MOMP is difficult to express in its native structure in the E. coli outer membrane (OM). Here, by co-expression of the Bam complex, we improved the expression and localization of recombinant Ct-MOMP in the E. coli OM. Under these conditions, recombinant Ct-MOMP appeared to assemble into a β-barrel conformation and express domains at the cell surface indicative of correct folding. The data indicate that limited availability of the Bam complex can be a bottleneck for the production of heterologous OM vaccine antigens, information that is also relevant for strategies aimed at producing recombinant OMV-based vaccines.

Keywords

• <i>Chlamydia trachomatis</i> major outer membrane protein
• β-barrel assembly machinery
• outer membrane protein
• <i>E. coli</i>
• OMV-based vaccine