Siderophore-Mediated Cargo Delivery to the Cytoplasm of Escherichia coli and Pseudomonas aeruginosa: Syntheses of Monofunctionalized Enterobactin Scaffolds and Evaluation of Enterobactin-Cargo Conjugate Uptake

• Main Authors: Zheng, Tengfei (Contributor), Bullock, Justin L. (Contributor), Nolan, Elizabeth M. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Chemical Engineering (Contributor), Massachusetts Institute of Technology. Department of Chemistry (Contributor)
• Format: Article
• Language: English
• Published: American Chemical Society (ACS), 2014-01-06T18:15:38Z.
• Subjects: Article
• Online Access: Get fulltext

The design and syntheses of monofunctionalized enterobactin (Ent, l- and d-isomers) scaffolds where one catecholate moiety of enterobactin houses an alkene, aldehyde, or carboxylic acid at the C5 position are described. These molecules are key precursors to a family of 10 enterobactin-cargo conjugates presented in this work, which were designed to probe the extent to which the Gram-negative ferric enterobactin uptake and processing machinery recognizes, transports, and utilizes derivatized enterobactin scaffolds. A series of growth recovery assays employing enterobactin-deficient E. coli ATCC 33475 (ent-) revealed that six conjugates based on l-Ent having relatively small cargos promoted E. coli growth under iron-limiting conditions whereas negligible-to-no growth recovery was observed for four conjugates with relatively large cargos. No growth recovery was observed for the enterobactin receptor-deficient strain of E. coli H1187 (fepA-) or the enterobactin esterase-deficient derivative of E. coli K-12 JW0576 (fes-), or when the d-isomer of enterobactin was employed. These results demonstrate that the E. coli ferric enterobactin transport machinery identifies and delivers select cargo-modified scaffolds to the E. coli cytoplasm. Pseudomonas aeruginosa PAO1 K648 (pvd-, pch-) exhibited greater promiscuity than that of E. coli for the uptake and utilization of the enterobactin-cargo conjugates, and growth promotion was observed for eight conjugates under iron-limiting conditions. Enterobactin may be utilized for delivering molecular cargos via its transport machinery to the cytoplasm of E. coli and P. aeruginosa thereby providing a means to overcome the Gram-negative outer membrane permeability barrier.
Kinship Foundation. Searle Scholars Program
Massachusetts Institute of Technology. Undergraduate Research Opportunities Program
Amgen Scholars Program
National Science Foundation (U.S.) (Grant CHE-9808061)
National Science Foundation (U.S.) (Grant DBI-9729592)