Dataset Information

A solute-binding protein in the closed conformation induces ATP hydrolysis in a bacterial ATP-binding cassette transporter involved in the import of alginate.

ABSTRACT: The Gram-negative bacterium Sphingomonas sp. A1 incorporates alginate into cells via the cell-surface pit without prior depolymerization by extracellular enzymes. Alginate import across cytoplasmic membranes thereby depends on the ATP-binding cassette transporter AlgM1M2SS (a heterotetramer of AlgM1, AlgM2, and AlgS), which cooperates with the periplasmic solute-binding protein AlgQ1 or AlgQ2; however, several details of AlgM1M2SS-mediated alginate import are not well-understood. Herein, we analyzed ATPase and transport activities of AlgM1M2SS after reconstitution into liposomes with AlgQ2 and alginate oligosaccharide substrates having different polymerization degrees (PDs). Longer alginate oligosaccharides (PD ? 5) stimulated the ATPase activity of AlgM1M2SS but were inert as substrates of AlgM1M2SS-mediated transport, indicating that AlgM1M2SS-mediated ATP hydrolysis can be stimulated independently of substrate transport. Using X-ray crystallography in the presence of AlgQ2 and long alginate oligosaccharides (PD 6-8) and with the humid air and glue-coating method, we determined the crystal structure of AlgM1M2SS in complex with oligosaccharide-bound AlgQ2 at 3.6 Å resolution. The structure of the ATP-binding cassette transporter in complex with non-transport ligand-bound periplasmic solute-binding protein revealed that AlgM1M2SS and AlgQ2 adopt inward-facing and closed conformations, respectively. These in vitro assays and structural analyses indicated that interactions between AlgM1M2SS in the inward-facing conformation and periplasmic ligand-bound AlgQ2 in the closed conformation induce ATP hydrolysis by the ATP-binding protein AlgS. We conclude that substrate-bound AlgQ2 in the closed conformation initially interacts with AlgM1M2SS, the AlgM1M2SS-AlgQ2 complex then forms, and this formation is followed by ATP hydrolysis.

SUBMITTER: Kaneko A

PROVIDER: S-EPMC5612102 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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A solute-binding protein in the closed conformation induces ATP hydrolysis in a bacterial ATP-binding cassette transporter involved in the import of alginate.

Kaneko Ai A Uenishi Kasumi K Maruyama Yukie Y Mizuno Nobuhiro N Baba Seiki S Kumasaka Takashi T Mikami Bunzo B Murata Kousaku K Hashimoto Wataru W

The Journal of biological chemistry 20170802 38

The Gram-negative bacterium <i>Sphingomonas</i> sp. A1 incorporates alginate into cells via the cell-surface pit without prior depolymerization by extracellular enzymes. Alginate import across cytoplasmic membranes thereby depends on the ATP-binding cassette transporter AlgM1M2SS (a heterotetramer of AlgM1, AlgM2, and AlgS), which cooperates with the periplasmic solute-binding protein AlgQ1 or AlgQ2; however, several details of AlgM1M2SS-mediated alginate import are not well-understood. Herein, ...[more]

PMID: 28768763

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Project description:Introduction: Legalization of medicinal cannabis around the world has led to an increase in the use of commercial cannabis-based products in the community. These cannabis-based products are being used in combination with conventional drugs to treat a variety of health conditions. Moreover, recreational cannabis-based products may be used in combination with other drugs. In this setting, there is increased potential for drug-drug interactions (DDIs) involving commercial cannabis-based products. Since DDIs can lead to serious adverse events, drug regulatory bodies require that every investigational drug be evaluated for DDI potential at metabolic enzymes and transporters. However, this seldom occurs for cannabis-based products due to legislation in many jurisdictions allowing a direct pathway to market. This study aimed to examine the inhibitory potential of three commercially available cannabis-based products at human ATP-binding cassette (ABC) and solute-carrier (SLC) transporters. Materials and Methods: Three commercial cannabis-based products (Spectrum Yellow™, Tweed Argyle, and Spectrum Red™) that contain differing concentrations of cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC) were evaluated for DDI potential at 12 drug transporters. HEK293 cells or vesicles expressing human ABC transporters (ABCB1, ABCC2, ABCG2, or ABCB11) and SLC transporters (SLC22A1, SLC22A2, SLC22A6, SLC22A8, SLCO1B1, SLCO1B3, SLC47A1, and SLC47A2) were used to measure transporter function. Results: Spectrum Yellow and Tweed Argyle inhibited ABCG2 transporter function. The IC50 value of Spectrum Yellow based on CBD and Δ9-THC content was 4.5 μM for CBD and 0.20 μM for Δ9-THC, and the IC50 value of Tweed Argyle was 9.3 μM for CBD and 6.0 μM for Δ9-THC. Tweed Argyle also inhibited ABCB11 transporter function with an IC50 value of 11.9 μM for CBD and 7.7 μM for Δ9-THC. SLC22A6, SLC22A1, SLC22A2, SLCO1B1, and SLCO1B3 transporter functions were modestly inhibited by high concentrations of the cannabis-based products. The three cannabis-based products did not inhibit ABCB1, ABCC2, SLC47A1, SLC47A2, or SLC22A8 transporters. Discussion: Novel findings were that the cannabis-based products inhibited ABCB11, SLC22A6, SLC22A1, SLC22A2, SLCO1B1, and SLCO1B3 (although modestly in most instances). Spectrum Yellow and Tweed Argyle potently inhibited ABCG2, and future in vivo DDI studies could be conducted to assess whether cannabis products affect the pharmacokinetics of medications that are ABCG2 substrates.

Dataset Information

A solute-binding protein in the closed conformation induces ATP hydrolysis in a bacterial ATP-binding cassette transporter involved in the import of alginate.

Publications

A solute-binding protein in the closed conformation induces ATP hydrolysis in a bacterial ATP-binding cassette transporter involved in the import of alginate.

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