Dataset Information

Selective Binding of a Toxin and Phosphatidylinositides to a Mammalian Potassium Channel

ABSTRACT: G-protein-gated inward rectifying potassium channels (GIRKs) require Gβγ subunits and phosphorylated phosphatidylinositides (PIPs) for gating. Although studies have provided insight into these interactions, the mechanism of how these events are modulated by Gβγ and the binding affinity between PIPs and GIRKs remains poorly understood. Here, native ion mobility mass spectrometry is employed to directly monitor small molecule binding events to mouse GIRK2. GIRK2 binds the toxin tertiapin Q and PIPs selectively and with significantly higher affinity than other phospholipids. A mutation in GIRK2 that causes a rotation in the cytoplasmic domain, similarly to Gβγ-binding to the wild-type channel, revealed differences in the selectivity towards PIPs More specifically, PIP isoforms known to weakly activate GIRKs have decreased binding affinity. Additionally, denaturing mass spectrometry and tryptic digest liquid chromatography mass spectrometry analysis was performed to confirm phosphorylation to GIRK2.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Mus Musculus (mouse)

SUBMITTER: Yang Liu

LAB HEAD: Arthur Laganowsky

PROVIDER: PXD012894 | Pride | 2019-04-02

REPOSITORIES: Pride

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Publications

Selective binding of a toxin and phosphatidylinositides to a mammalian potassium channel.

Liu Yang Y LoCaste Catherine E CE Liu Wen W Poltash Michael L ML Russell David H DH Laganowsky Arthur A

Nature communications 20190322 1

G-protein-gated inward rectifying potassium channels (GIRKs) require G<sub>βγ</sub> subunits and phosphorylated phosphatidylinositides (PIPs) for gating. Although studies have provided insight into these interactions, the mechanism of how these events are modulated by G<sub>βγ</sub> and the binding affinity between PIPs and GIRKs remains poorly understood. Here, native ion mobility mass spectrometry is employed to directly monitor small molecule binding events to mouse GIRK2. GIRK2 binds the tox ...[more]

PMID: 30902995

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Project description:DNA affinity chromatography with the promoter region of the Corynebacterium glutamicum pck gene, encoding phosphoenolpyruvate carboxykinase (PEPCk), led to the isolation of four transcriptional regulators, i.e., RamA, GntR1, GntR2 and IolR. Determination of the PEPCk activity of the deletion mutants M-NM-^TramA, M-NM-^TgntR1M-NM-^TgntR2, and M-NM-^TiolR indicated that RamA represses pck during growth on glucose about twofold, whereas GntR1, GntR2, and IolR activate pck expression about twofold, irrespective whether glucose or acetate served as carbon source. The DNA binding sites of the four regulators in the pck promoter region were identified and their positions correlated with the predicted functions as repressor or activators. The iolR gene is located upstream and in divergent orientation to a iol gene cluster, encoding proteins involved in myo-inositol uptake and degradation. Comparative DNA microarray analysis of the M-NM-^TiolR mutant and the parental wild-type revealed strongly elevated (>100-fold) mRNA levels of the iol genes in the mutant, indicating that the primary function of IolR is the repression of the iol genes. IolR binding sites were identified in the promoter regions of iolC, iolT and iolR itself, which presumably is subject to negative autoregulation. A consensus DNA-binding motif was identified (5M-bM-^@M-^Y-KGWCHTRACA-3M-bM-^@M-^Y) which corresponds well to those of other GntR-type regulators of the HutC family. Taken together, our results disclose a complex regulation of the pck gene in C. glutamicum and identify IolR as an efficient repressor of genes involved in myo-inositol catabolism of this organism. To identify genes that are potentially regulated by IolR, the transcriptome profile of the iolR deletion strain was compared to that of the WT using DNA microarray analysis. The strains were grown in CGXII minimal medium with 4% (wt/vol) glucose as sole carbon source and RNA was isolated from cells harvested in the early exponential growth phase (OD600 of about 5). The transcriptome comparison was performed in triplicate starting from independent cultures. The second replicate included a dye-swap.

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Dataset Information

Selective Binding of a Toxin and Phosphatidylinositides to a Mammalian Potassium Channel

Publications

Selective binding of a toxin and phosphatidylinositides to a mammalian potassium channel.

Similar Datasets

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