Chaperone Proteins Skp and FkpA May Perform Distinct Roles Facilitating BrkA Secretion in Escherichia coli

Abstract

Chaperone proteins assist the translocation of autotransporter proteins across the periplasm, promoting their proper folding and insertion into the outer membrane. It has been shown that chaperone proteins in the periplasm have functionally redundant roles. However, the role of chaperone proteins in BrkA secretion have been understudied. In this study we investigated the involvement of chaperone proteins Skp and FkpA in the folding and secretion of BrkA in Escherichia coli. An antisense construct targeting fkpA mRNA was constructed and transformed into a Skp knockout strain. Growth curve assays were used to assess growth phenotypes and showed impaired growth in strains expressing both BrkA and the fkpA antisense RNA. Through Western blot analysis, we found that Skp and FkpA may be necessary in protecting BrkA from degradation, with Skp possibly being essential for facilitating BrkA cleavage, while FkpA may contribute through an unknown mechanism. Overall, our study provides insight regarding chaperone proteins in BrkA secretion.