Structure and mechanotransmission mechanism of the MacB ABC transporter superfamily

Crow, A.; Greene, Nicholas P.; Kaplan, Elise; Koronakis, Vassilis

doi:10.1073/pnas.1712153114

Cited by 134 publications

(207 citation statements)

References 32 publications

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“…BceAB-type systems belong to the type VII ABC transporter superfamily, of which the Escherichia coli macrolide resistance transporter MacB is the paradigm example (22). MacB was recently shown to act according to a molecular bellows mechanism and expel its substrate from the periplasm across the outer membrane via the TolC exit duct by undergoing extensive conformational changes in its periplasmic domain (23). This mode of "transport," which does not involve physical movement of a substrate across a membrane but instead uses intracellular ATP hydrolysis to perform mechanical work in the periplasm, was termed "mechanotransmission" (23).…”

Section: Resultsmentioning

confidence: 99%

BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis

Kobras

Piepenbreier

Emenegger

et al. 2020

Antimicrob Agents Chemother

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Resistance against cell wall-active antimicrobial peptides in bacteria is often mediated by transporters. In low-GC-content Gram-positive bacteria, a common type of such transporters is BceAB-like systems, which frequently provide highlevel resistance against peptide antibiotics that target intermediates of the lipid II cycle of cell wall synthesis. How a transporter can offer protection from drugs that are active on the cell surface, however, has presented researchers with a conundrum. Multiple theories have been discussed, ranging from removal of the peptides from the membrane and internalization of the drug for degradation to removal of the cellular target rather than the drug itself. To resolve this much-debated question, we here investigated the mode of action of the transporter BceAB of Bacillus subtilis. We show that it does not inactivate or import its substrate antibiotic bacitracin. Moreover, we present evidence that the critical factor driving transport activity is not the drug itself but instead the concentration of drug-target complexes in the cell. Our results, together with previously reported findings, lead us to propose that BceAB-type transporters act by transiently freeing lipid II cycle intermediates from the inhibitory grip of antimicrobial peptides and thus provide resistance through target protection of cell wall synthesis. Target protection has so far only been reported for resistance against antibiotics with intracellular targets, such as the ribosome. However, this mechanism offers a plausible explanation for the use of transporters as resistance determinants against cell wall-active antibiotics in Gram-positive bacteria where cell wall synthesis lacks the additional protection of an outer membrane.

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Section: Resultsmentioning

confidence: 99%

BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis

Kobras

Piepenbreier

Emenegger

et al. 2020

Antimicrob Agents Chemother

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“…How MacB can protect these bacteria within host by efflux of physiological substrates bears further investigation. Recently, an electron cryomicroscopy structure of MacAB–TolC and a crystal structure of MacB were determined 30–32 . Despite this progress, many questions regarding MacAB remain.…”

Section: Discussionmentioning

confidence: 99%

“…Recently, an electron cryomicroscopy structure of MacAB-TolC and a crystal structure of MacB were determined. [30][31][32] Despite this progress, many questions regarding MacAB remain. For example, the absence of a substrate-bound structure is the biggest barrier for understanding the mechanism of substrate recognition by MacB.…”

Section: Discussionmentioning

confidence: 99%

An efflux inhibitor of the MacAB pump in Salmonella enterica serovar Typhimurium

Yamagishi

Nakano

Yamasaki

et al. 2020

Microbiology and Immunology

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Multidrug efflux pumps play an important role in bacterial multidrug resistance by actively excreting antibiotics. The ATP‐binding cassette–type drug efflux pump MacAB was originally reported as a macrolide‐specific pump. MacAB is also known to be required for the virulence of Salmonella enterica serovar Typhimurium following oral infection in mice. Here, we performed a screening of inhibitors of Salmonella MacAB and found a compound that increased the susceptibility of a MacAB‐expressing strain to macrolides. It was previously reported that MacAB is required to resist peroxide‐mediated killing in vitro and that a supernatant of wild‐type Salmonella rescues the growth defect of a macAB mutant in H2O2. In this study, we also found that the MacAB inhibitor reduced the ability of the supernatant to rescue Salmonella cells in H2O2. This compound could lead to a better understanding of the function of MacAB.

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“…Recently, the structure of A. actinomycetemcomitans MacB was reported and suggested to be a structural paradigm for the ABC3 transporter superfamily that includes FtsX (38). MacB was proposed to function as a mechanical pump to drive enterotoxin transport through TolC in E. coli (38). Crow et.…”

Section: Discussionmentioning

confidence: 99%

“…Crow et. al found that MacB itself did not transport enterotoxin but drove TolC to transport it instead, due to the lack of a central cavity in the MacB structure (38). As such, they proposed that MacB as a model for other “mechanotransmitters” belonging to this same ABC3 transporter superfamily.…”

Section: Discussionmentioning

confidence: 99%

Structure of the large extracellular loop of FtsX and its interaction with the essential peptidoglycan hydrolase PcsB inStreptococcus pneumoniae

Rued

Alcorlo

Edmonds

et al. 2018

Preprint

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word count: 163 words 20 Text word count: 5,664 words 21 22 23 2 ABSTRACT 24Streptococcus pneumoniae is a leading killer of infants and immunocompromised adults 25 and has become increasingly resistant to major antibiotics. Therefore, the development 26 of new antibiotic strategies is desperately needed. Targeting bacterial cell division is 27 one such strategy, specifically targeting essential proteins for the synthesis and 28 breakdown of peptidoglycan. One complex important to this process is FtsEX. FtsEX 29 comprises an integral membrane protein (FtsX) and cytoplasmic ATPase (FtsE) that 30 resembles an ATP-binding cassette (ABC) transporter. Here, we present NMR solution 31 structural and crystallographic models of the large extracellular domain of FtsX, denoted 32 ECL1. The structure of ECL1 reveals an upper extended β-hairpin and a lower α-helical 33 lobe, each extending from a mixed α-β core. The helical lobe mediates a physical 34 interaction with the peptidoglycan hydrolase PcsB, via the coiled-coil domain of PcsB 35 (PcsB-CC). Characterization of S. pneumoniae D39 derived strains harboring mutations 36 in the α-helical lobe shows that this subdomain is essential for cell viability and required 37 for proper cell division of S. pneumoniae. 38 39 IMPORTANCE FtsX is a ubiquitous bacterial integral membrane protein involved in cell 40 division that regulates the activity of peptidoglycan (PG) hydrolases. FtsX is 41representative of a large group of ABC3 superfamily proteins that function as 42 "mechanotransmitters," proteins that relay signals from inside to the outside of the cell. 43Here we present a structural characterization of the large extracellular loop (ECL1) of 44 FtsX from the human opportunistic pathogen Streptococcus pneumoniae. We show a 45 direct interaction between the peptidoglycan hydrolase PcsB and FtsX, and 46 3 demonstrate that this interaction is essential for cell viability. As such, FtsX represents 47 an attractive, conserved target for the development of new classes of antibiotics. 48 49 65 From Mycobacterium tuberculosis to Caulobacter crescentus, the ABC-66 transporter-like protein complex FtsEX acts as a key regulator of PG hydrolysis and 67 divisome assembly (16-19). The proposed mechanism of FtsEX activation of PG 68 hydrolases is as follows. FtsE, upon sensing an unknown signal from inside the cell, 69 4 hydrolyzes ATP to ADP. Hydrolysis causes a conformational change transmitted 70 through the membrane via FtsX, an integral membrane protein with two extracellular 71 loops, denoted the large (ECL1) and small (ECL2) loops. These extracellular loops 72interact with either the cell wall hydrolases or with effector proteins, which results in 73 activation of PG hydrolysis via an unknown mechanism (16, 18,(20)(21)(22)(23)(24)(25). In E. coli, it has 74 been demonstrated that FtsX interacts with the effector protein EnvC to activate the PG 75 amidases AmiA and AmiB (24, 25). In addition, FtsX interacts with other division 76 proteins such as FtsA, where it regulates the polyme...

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Structure and mechanotransmission mechanism of the MacB ABC transporter superfamily

Cited by 134 publications

References 32 publications

BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis

BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis

An efflux inhibitor of the MacAB pump in Salmonella enterica serovar Typhimurium

Structure of the large extracellular loop of FtsX and its interaction with the essential peptidoglycan hydrolase PcsB inStreptococcus pneumoniae

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