The DsbA Chaperone Protein May Be Necessary for Outer Membrane Secretion of BrkA

Abstract

Gram-negative bacteria utilize specialized secretion systems to transport proteins across their outer membrane and into the extracellular environment. Among these systems, autotransporter proteins, like BrkA in Bordetella pertussis, autonomously localize to the bacterial cell surface, increasing virulence and inhibiting bactericidal immune responses from hosts. While periplasmic chaperone proteins have been shown to be involved in autotransporter biogenesis, not all their specific roles in BrkA secretion, as it transits through the periplasm, are well understood. DsbA and SurA are two chaperone proteins found in the periplasm of Gram-negative bacteria. SurA has been previously implicated in the secretion of BrkA, while DsbA does not interact directly with BrkA, it’s interactions with SurA and whether these aid in the secretion are unknown. We aimed to explore whether DsbA affects BrkA surface expression in Escherichia coli through loss-of-function experiments. Our results suggest that DsbA may play a role in BrkA secretion. The experimental outcomes indicate a possible role for DsbA in facilitating BrkA secretion, implicating a wider involvement of periplasmic factors in the complex orchestration of BrkA biogenesis and secretion.