A Fluorescent Transport Assay Enables Studying AmpG Permeases Involved in Peptidoglycan Recycling and Antibiotic Resistance

作者：Perley-Robertson, G. Evan; Yadav, Anuj K.; Winogrodzki, Judith L.; Stubbs, Keith A.; Mark, Brian L.; Vocadlo, David J.^*

来源：ACS Chemical Biology, 2016, 11(9): 2626-2635.

DOI：10.1021/acschembio.6b00552

• BETA-LACTAMASE INDUCTION
• PSEUDOMONAS-AERUGINOSA
• MEMBRANE-TRANSPORT
• ESCHERICHIA-COLI
• GLUCOSE-UPTAKE
• EXPRESSION
• INHIBITORS
• MUTATIONS
• MOLECULE
• BACTERIA

Inducible AmpC beta-lactamases deactivate a broad-spectrum of beta-lactam antibiotics and afford antibiotic resistance in many Gram-negative bacteria. The disturbance of peptidoglycan recycling caused by beta-lactam antibiotics leads to accumulation of GlcNAc-1,6-anhydroMurNAc-peptides, which are transported by AmpG to the cytoplasm where they are processed into AmpC inducers. AmpG transporters are poorly understood; however, their loss restores susceptibility toward beta-lactam antibiotics, highlighting AmpG as a potential target for resistance-attenuating therapeutics. We prepare a GlcNAc-1,6-anhydroMurNAc-fluorophore conjugate and, using live E. coli spheroplasts, quantitatively analyze its transport by AmpG and inhibition of this process by a competing substrate. Further, we use this transport assay to evaluate the function of two AmpG homologues from Pseudomonas aeruginosa and show that P. aeruginosa AmpG (Pa-AmpG) but not AmpP (Pa-AmpP) transports this probe substrate. We corroborate these results by AmpC induction assays with Pa-AmpG and Pa-AmpP. This fluorescent AmpG probe and spheroplast-based transport assay will enable improved understanding of PG recycling and of permeases from the major facilitator superfamily of transport proteins and may aid in identification of AmpG antagonists that combat AmpC-mediated resistance toward beta-lactam antibiotics.

• 出版日期2016-9