Overproducing the BAM complex improves secretion of difficult-to-secrete recombinant autotransporter chimeras

Trang H. Phan, Coen Kuijl, Dung T. Huynh, Wouter S.P. Jong, Joen Luirink, Peter van Ulsen*

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review


Monomeric autotransporters have been used extensively to transport recombinant proteins or protein domains to the cell surface of Gram-negative bacteria amongst others for antigen display. Genetic fusion of such antigens into autotransporters has yielded chimeras that can be used for vaccination purposes. However, not every fusion construct is transported efficiently across the cell envelope. Problems occur in particular when the fused antigen attains a relatively complex structure in the periplasm, prior to its translocation across the outer membrane. The latter step requires the interaction with periplasmic chaperones and the BAM (β-barrel assembly machinery) complex in the outer membrane. This complex catalyzes insertion and folding of β-barrel outer membrane proteins, including the β-barrel domain of autotransporters. Here, we investigated whether the availability of periplasmic chaperones or the BAM complex is a limiting factor for the surface localization of difficult-to-secrete chimeric autotransporter constructs. Indeed, we found that overproduction of in particular the BAM complex, increases surface display of difficult-to-secrete chimeras. Importantly, this beneficial effect appeared to be generic not only for a number of monomeric autotransporter fusions but also for fusions to trimeric autotransporters. Therefore, overproduction of BAM might be an attractive strategy to improve the production of recombinant autotransporter constructs.

Original languageEnglish
Article number176
JournalMicrobial Cell Factories
Issue number1
Publication statusPublished - Dec 2021

Bibliographical note

Funding Information:
TP was funded by the BAC-Vactory program, domain of Applied and Engineering Sciences (TTW) of the Netherlands Organization for Scientific Research (NWO). DH received funding from the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie Grant agreement No. 812915.

Publisher Copyright:
© 2021, The Author(s).

Copyright 2021 Elsevier B.V., All rights reserved.


  • BAM complex
  • Hbp
  • Outer membrane proteins
  • Surface display
  • Type V secretion systems


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