Open AccessColicin-Mediated Transport of DNA through the Iron Transporter FepA
Author(s) -
Ruth Cohen-Khait,
Ameya Harmalkar,
Phuong Pham,
Melissa N. Webby,
Nicholas G. Housden,
Emma Elliston,
Jonathan T. S. Hopper,
Shabaz Mohammed,
Carol V. Robinson,
Jeffrey J. Gray,
Colin Kleanthous
Publication year - 2021
Publication title -
mbio
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.562
H-Index - 121
eISSN - 2161-2129
pISSN - 2150-7511
DOI - 10.1128/mbio.01787-21
Subject(s) - colicin , periplasmic space , bacteriocin , escherichia coli , cell envelope , bacterial outer membrane , bacteria , microbiology and biotechnology , biology , bacterial cell structure , chemistry , biophysics , biochemistry , genetics , gene
Colicins are protein antibiotics deployed by Escherichia coli to eliminate competing strains. Colicins frequently exploit outer membrane (OM) nutrient transporters to penetrate the selectively permeable bacterial cell envelope. Here, by applying live-cell fluorescence imaging, we were able to monitor the entry of the pore-forming toxin colicin B (ColB) into E. coli and localize it within the periplasm. We further demonstrate that single-stranded DNA coupled to ColB can also be transported to the periplasm, emphasizing that the import routes of colicins can be exploited to carry large cargo molecules into bacteria. Moreover, we characterize the molecular mechanism of ColB association with its OM receptor FepA by applying a combination of photoactivated cross-linking, mass spectrometry, and structural modeling. We demonstrate that complex formation is coincident with large-scale conformational changes in the colicin. Thereafter, active transport of ColB through FepA involves the colicin taking the place of the N-terminal half of the plug domain that normally occludes this iron transporter.