Quantitative real-time analysis of the efflux by the MacAB-TolC tripartite efflux pump clarifies the role of ATP hydrolysis within mechanotransmission mechanism

Abstract Tripartite efflux pumps built around ATP-binding cassette (ABC) transporters are membrane protein machineries that perform vectorial export of a large variety drugs and virulence factors from Gram negative bacteria, using ATP-hydrolysis as energy source. Determining the number ATP molecules consumed per transport cycle is essential to understanding efficiency substrate transport. Using reconstituted pump in mimic environment, we show MacAB-TolC Escherichia coli couples with high efficiency. Contrary predictions currently prevailing “molecular bellows” model MacB-operation, which assigns power stroke by nucleotide binding domains transporter, utilizing novel assay, report clear synchronization transfer ATP-hydrolysis, suggesting at least some for provided ATP-hydrolysis. Our findings narrow down window consumption step results transition into TolC-channel, expanding current MacB-based tripartite assemblies. Based on propose modified MacB within context complex assembly.