Open AccessSpecific TonB‐ExbB‐ExbD energy transduction systems required for ferric enterobactin acquisition in Campylobacter
Author(s) -
Zeng Ximin,
Xu Fuzhou,
Lin Jun
Publication year - 2013
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12221
Subject(s) - campylobacter , enterobactin , biology , bacterial outer membrane , campylobacter jejuni , siderophore , mutagenesis , microbiology and biotechnology , biophysics , computational biology , genetics , bacteria , biochemistry , escherichia coli , gene , mutant
Abstract Ferric enterobactin (FeEnt) acquisition plays a critical role in the pathophysiology of Campylobacter , the leading bacterial cause of human gastroenteritis in industrialized countries. In Campylobacter , the surface‐exposed receptor, CfrA or CfrB, functions as a ‘gatekeeper’ for initial binding of FeEnt. Subsequent transport across the outer membrane is energized by TonB‐ExbB‐ExbD energy transduction systems. Although there are up to three TonB‐ExbB‐ExbD systems in Campylobacter , the cognate components of TonB‐ExbB‐ExbD for FeEnt acquisition are still largely unknown. In this study, we addressed this issue using complementary molecular approaches: comparative genomic analysis, random transposon mutagenesis and site‐directed mutagenesis in two representative C. jejuni strains, NCTC 11168 and 81–176. We demonstrated that CfrB could interact with either TonB2 or TonB3 for efficient Ent‐mediated iron acquisition. However, TonB3 is a dominant player in the CfrA‐dependent pathway. The ExbB2 and ExbD2 components were essential for both CfrA‐ and CfrB‐dependent FeEnt acquisition. Sequences analysis identified potential TonB boxes in CfrA and CfrB, and the corresponding binding sites in TonB. In conclusion, these findings identify specific TonB‐ExbB‐ExbD energy transduction components required for FeEnt acquisition, and provide insights into the complex molecular interactions of FeEnt acquisition systems in Campylobacter .