Cryo‐EM of ABC transporters: an ice‐cold solution to everything?

Januliene, Dovile; Moeller, Arne

doi:10.1002/1873-3468.13989

Cited by 23 publications

(19 citation statements)

References 147 publications

(232 reference statements)

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“…In inward-facing (IF) conformations, the nucleotide-binding domains (NBDs) are separated, and substrates can access a large binding cavity that is open to the lower membrane leaflet and cytoplasm. ATP-induced dimerization of the NBDs promotes large rearrangements of the transmembrane domains (TMDs) between an IF and outward-facing (OF) conformation, from which the substrate is released ( 8 ). Pgp structures with bound substrates and inhibitors in IF conformation have revealed one or more overlapping binding sites ( 9-13 ), and multimodal binding mechanisms for chemically related compounds have been proposed ( 1, 9 ).…”

Section: Main Textmentioning

confidence: 99%

Tracing the substrate translocation mechanism in P-glycoprotein

Gewering

Waghray

Parey

et al. 2022

Preprint

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P-glycoprotein (Pgp) is a highly dynamic ATP-binding cassette transporter that confers cancer multidrug resistance and mediates the bioavailability and pharmacokinetics of many drugs. Structural and biochemical data have provided insights into the binding of diverse compounds, but how they are translocated through the membrane has remained elusive. The biggest hurdle to address this fundamental question has been isolating and characterizing the short-lived transition states during transport. Here, we covalently attached a cyclopeptide substrate to discrete sites of Pgp. Cryo-EM analyses of inward- and outward-facing conformations enabled tracing of the substrate passage and revealed how a cascade of conformational changes in transmembrane helix 1 drives substrate movement across the membrane bilayer upon ATP binding. Observation of a double substrate-bound outward-facing conformation suggests that Pgp can co-transport two compounds simultaneously.One-Sentence SummaryCryo-EM reveals the substrate transport pathway and mechanism of P-glycoprotein from initial binding to release.

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Section: Main Textmentioning

confidence: 99%

Tracing the substrate translocation mechanism in P-glycoprotein

Gewering

Waghray

Parey

et al. 2022

Preprint

Self Cite

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“…In very recent years, structural biology has rapidly and exponentially increased our understanding of membrane transporters (111)(112)(113). Recent advancements e.g., in X-ray crystallography and cryogenic electron microscopy (cryo-EM) have led to today's high-resolution (< 2.5 Å) protein structures, which are rich in information.…”

Section: Molecular Dynamics Simulations (Mds) Improve Understanding O...mentioning

confidence: 99%

Pharmacoproteomics of Brain Barrier Transporters and Substrate Design for the Brain Targeted Drug Delivery

et al. 2022

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One of the major reasons why central nervous system (CNS)-drug development has been challenging in the past, is the barriers that prevent substances entering from the blood circulation into the brain. These barriers include the blood-brain barrier (BBB), blood-spinal cord barrier (BSCB), blood-cerebrospinal fluid barrier (BCSFB), and blood-arachnoid barrier (BAB), and they differ from each other in their transporter protein expression and function as well as among the species. The quantitative expression profiles of the transporters in the CNS-barriers have been recently revealed, and in this review, it is described how they affect the pharmacokinetics of compounds and how these expression differences can be taken into account in the prediction of brain drug disposition in humans, an approach called pharmacoproteomics. In recent years, also structural biology and computational resources have progressed remarkably, enabling a detailed understanding of the dynamic processes of transporters. Molecular dynamics simulations (MDS) are currently used commonly to reveal the conformational changes of the transporters and to find the interactions between the substrates and the protein during the binding, translocation in the transporter cavity, and release of the substrate on the other side of the membrane. The computational advancements have also aided in the rational design of transporter-utilizing compounds, including prodrugs that can be actively transported without losing potency towards the pharmacological target. In this review, the state-of-art of these approaches will be also discussed to give insights into the transporter-mediated drug delivery to the CNS.

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“…Indeed, the painful history of ABC transporter structures [ 207 , 265 ], shows that even higher resolution structures suffer from their static nature that only reflects snapshots of a catalytic cycle. Thus, we need atomic structures reflecting more than a single conformation and possibly many transition states [ 352 ], as well as extensive validation by biochemistry and genetics, to validate their biological relevance and define catalytic cycles. Furthermore, there is an unmet need for more interdisciplinary collaborations that also engage alternative structural approaches like NMR [ 353 , 354 , 355 , 356 ] as well as complementary biophysical methods [ 265 , 357 , 358 , 359 ] to expand our mechanistic views of ABC transporters in all living kingdoms.…”

Section: Conclusion and Future Perspectivesmentioning

confidence: 99%

Multidrug Resistance in Mammals and Fungi—From MDR to PDR: A Rocky Road from Atomic Structures to Transport Mechanisms

Khunweeraphong

Kuchler

2021

IJMS

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Multidrug resistance (MDR) can be a serious complication for the treatment of cancer as well as for microbial and parasitic infections. Dysregulated overexpression of several members of the ATP-binding cassette transporter families have been intimately linked to MDR phenomena. Three paradigm ABC transporter members, ABCB1 (P-gp), ABCC1 (MRP1) and ABCG2 (BCRP) appear to act as brothers in arms in promoting or causing MDR in a variety of therapeutic cancer settings. However, their molecular mechanisms of action, the basis for their broad and overlapping substrate selectivity, remains ill-posed. The rapidly increasing numbers of high-resolution atomic structures from X-ray crystallography or cryo-EM of mammalian ABC multidrug transporters initiated a new era towards a better understanding of structure–function relationships, and for the dynamics and mechanisms driving their transport cycles. In addition, the atomic structures offered new evolutionary perspectives in cases where transport systems have been structurally conserved from bacteria to humans, including the pleiotropic drug resistance (PDR) family in fungal pathogens for which high resolution structures are as yet unavailable. In this review, we will focus the discussion on comparative mechanisms of mammalian ABCG and fungal PDR transporters, owing to their close evolutionary relationships. In fact, the atomic structures of ABCG2 offer excellent models for a better understanding of fungal PDR transporters. Based on comparative structural models of ABCG transporters and fungal PDRs, we propose closely related or even conserved catalytic cycles, thus offering new therapeutic perspectives for preventing MDR in infectious disease settings.

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Cryo‐EM of ABC transporters: an ice‐cold solution to everything?

Cited by 23 publications

References 147 publications

Tracing the substrate translocation mechanism in P-glycoprotein

Tracing the substrate translocation mechanism in P-glycoprotein

Pharmacoproteomics of Brain Barrier Transporters and Substrate Design for the Brain Targeted Drug Delivery

Multidrug Resistance in Mammals and Fungi—From MDR to PDR: A Rocky Road from Atomic Structures to Transport Mechanisms

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