The FhaB Prodomain of Bordetella Affects the Biogenesis of Filamentous Hemaggluttinin, Influencing Bordetella Virulence

The FhaB Prodomain of Bordetella Affects the Biogenesis of Filamentous Hemaggluttinin, Influencing Bordetella Virulence Public Deposited

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Noel, Christopher Robert
- Affiliation: School of Medicine, Department of Microbiology and Immunology

Abstract

Two-partner secretion (TPS) systems use beta-barrel proteins of the Omp85-TpsB superfamily to transport large exoproteins across the outer membranes of Gram-negative bacteria. The Bordetella FHA/FhaC proteins are prototypical of TPS systems in which the exoprotein contains a large C-terminal prodomain that is removed during translocation. Although it is known that the FhaB prodomain is required for FHA function in vivo, its role in FHA maturation has remained mysterious. We show here that the FhaB prodomain is required for the extracellularly located mature C-terminal domain (MCD) of FHA to achieve its proper conformation. We show that the C-terminus of the prodomain is retained intracellularly and that sequences within the N-terminus of the prodomain are required for this intracellular localization. We also identify the MCD and prodomain N-terminus (PNT) as determinants of mature FHA release efficiency. Finally, we characterize subdomains at the C-terminus of the prodomain and their effects on FHA biogenesis and Bordetella virulence. Our data support a model in which the intracellularly located prodomain affects the final conformation of the extracellularly located MCD.

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