Structural insights into outer membrane asymmetry maintenance in Gram-negative bacteria by MlaFEDB

Tang, Xiaodi; Chang, Shenghai; Wen, Qian; Luo, Qinghua; Chen, Yuejia; Jia, Zhi Xin; Coleman, James L.; Zhang, Ke; Wang, Ting; Zhang, Zhibo; Zhang, Changbin; Zhu, Xiaofeng; Wei, Xiawei; Dong, Changjiang; Zhang, Xing; Dong, Haohao

doi:10.1038/s41594-020-00532-y

Cited by 58 publications

(88 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, the export of de novo synthesized phospholipids to the outer membrane during cell growth might be driven by Mla (35). The Mla system consists of an MlaFEDB complex in the inner membrane, MlaA-porin in the outer membrane, and the shuttle on May 9, 2021 by guest http://aac.asm.org/ Downloaded from protein MlaC in the periplasmic region (35)(36)(37). MlaF interacts with MlaB, to comprise the cytoplasmic portion of the MlaFEDB complex (44), which drives phospholipid trafficking across the bacterial envelope to maintain outer membrane integrity.…”

Section: Discussionmentioning

confidence: 99%

Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments

Liu

Gang

Wang-ping³

et al. 2021

Antimicrob Agents Chemother

View full text Add to dashboard Cite

Aeromonas hydrophila , a heterotrophic and Gram-negative bacterium, has attracted considerable attention owing to the increasing prevalence of reported infections. Colistin is a last-resort antibiotic that can treat life-threatening infections caused by multidrug-resistant gram-negative bacteria. However, the mechanisms underlying colistin resistance in A. hydrophila remain unclear. The present study reveals four novel colistin resistance mechanisms in A. hydrophila : (i) EnvZ/OmpR upregulates the expression of the arnBCADTEF operon to mediate LPS modification by 4-amino-4-deoxy-L-arabinose; (ii) EnvZ/OmpR regulates the expression of the autotransporter gene 3832 to decrease outer membrane permeability in response to colistin; (iii) deletion of envZ/ompR activates PhoP/PhoQ, which functions as a substitute two-component system to mediate the addition of phosphoethanolamine to lipid A via pmrC; and (iv) the mlaF D173A mutant confers high-level colistin resistance via upregulation of the Mla pathway. The EnvZ/OmpR two-component system-mediated resistance mechanism is the leading form of colistin resistance in A. hydrophila , which enables it to rapidly generate low- to medium-level colistin resistance. As colistin concentrations in the environment continue to rise, antibiotic resistance mediated by EnvZ/OmpR becomes insufficient to ensure bacterial survival. Consequently, A. hydrophila has developed a mlaF mutation that results in high-level colistin resistance. Our findings indicate that A. hydrophila can thrive in a complex environment through various colistin resistance mechanisms.

show abstract

Section: Discussionmentioning

confidence: 99%

Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments

Liu

Gang

Wang-ping³

et al. 2021

Antimicrob Agents Chemother

View full text Add to dashboard Cite

show abstract

“…This ensues the reversible partitioning of the PL molecule(s) between the lipid binding pockets of MlaC and the complex, even in the absence of ATP. While MlaD hexamers alone bind PLs much less strongly than MlaC (15), the MlaFEDB complex, where several structures now reveal a combined lipid binding cavity formed by both MlaD and MlaE (19)(20)(21)(22)(23), must possess strong affinity for PLs, likely comparable to MlaC. The trajectory of PL movement between the two binding sites remains to be clarified.…”

Section: Discussionmentioning

confidence: 99%

“…Yet, high sensitivity imparted by the use of [ 14 C]-labelled lipids allowed us to identify the key role ATP hydrolysis play in ultimately driving PL transport in the retrograde fashion. In the midst of preparing this manuscript, Tang et al have independently developed an indirect assay using non-native fluorescent lipids, and similarly reported that the Mla pathway mediates ATP-dependent retrograde PL transport in vitro (20). While they did not detect the spontaneous retrograde step, our complementary assays collectively establish the directionality of the system.…”

Section: Discussionmentioning

confidence: 99%

ATP disrupts lipid binding equilibrium to drive retrograde transport critical for bacterial outer membrane asymmetry

Low

Thong

Chng

2021

Preprint

View full text Add to dashboard Cite

The hallmark of the Gram-negative bacterial envelope is the presence of the outer membrane (OM). The OM is asymmetric, comprising lipopolysaccharides (LPS) in the outer leaflet and phospholipids (PLs) in the inner leaflet; this critical feature confers permeability barrier function against external insults, including antibiotics. To maintain OM lipid asymmetry, the OmpC-Mla system is believed to remove aberrantly localized PLs from the OM and transport them to the inner membrane (IM). Key to the system in driving lipid trafficking is the MlaFEDB ABC transporter complex in the IM, but mechanistic details, including transport directionality, remain enigmatic. Here, we develop a sensitive point-to-point in vitro lipid transfer assay that allows direct tracking of [14C]-labelled PLs between the periplasmic chaperone MlaC and MlaFEDB reconstituted into nanodiscs. We reveal that MlaC spontaneously transfers PLs to the IM transporter in an MlaD-dependent manner that can be further enhanced by coupled ATP hydrolysis. In addition, we show that MlaD is important for modulating productive coupling between ATP hydrolysis and such retrograde PL transfer. We further demonstrate that spontaneous PL transfer also occurs from MlaFEDB to MlaC, but such anterograde movement is instead abolished by ATP hydrolysis. Our work uncovers a model where PLs reversibly partition between two lipid binding sites in MlaC and MlaFEDB, and ATP binding and/or hydrolysis shift this equilibrium to ultimately drive retrograde PL transport by the OmpC-Mla system. These mechanistic insights will inform future efforts towards discovering new antibiotics against Gram-negative pathogens.

show abstract

“…The resulting debate as to whether the Mla system drives retrograde versus anterograde phospholipid transport has called for the reconstitution of the inner and outer membrane Mla components into proteoliposomes, as was achieved previously for the lipopolysaccharide (LPS) transport system 1 . In this issue of Nature Structural & Molecular Biology, Tang et al 2 report a high resolution cryo-EM structure of the Mla inner membrane ABC transporter complex. The authors also reconstitute the entire Mla system into inner and outer membrane proteoliposomes.…”

Section: Russell E Bishopmentioning

confidence: 99%

Phospholipid transporter shifts into reverse

Bishop

2020

Nat Struct Mol Biol

View full text Add to dashboard Cite

Structural insights into outer membrane asymmetry maintenance in Gram-negative bacteria by MlaFEDB

Cited by 58 publications

References 64 publications

Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments

Various Novel Colistin Resistance Mechanisms Interact To Facilitate Adaptation of Aeromonas hydrophila to Complex Colistin Environments

ATP disrupts lipid binding equilibrium to drive retrograde transport critical for bacterial outer membrane asymmetry

Phospholipid transporter shifts into reverse

Contact Info

Product

Resources

About