ORCID Profile
0000-0001-6654-114X
Current Organisations
IT University of Copenhagen
,
Københavns Universitet
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Biochemistry and Cell Biology | Structural Biology (incl. Macromolecular Modelling) | Biological Physics
Expanding Knowledge in the Chemical Sciences | Expanding Knowledge in the Biological Sciences |
Publisher: Springer Science and Business Media LLC
Date: 17-03-2022
DOI: 10.1038/S41467-022-28984-4
Abstract: Unlike classical voltage-gated sodium (Na V ) channels, Na X has been characterized as a voltage-insensitive, tetrodotoxin-resistant, sodium (Na + )-activated channel involved in regulating Na + homeostasis. However, Na X remains refractory to functional characterization in traditional heterologous systems. Here, to gain insight into its atypical physiology, we determine structures of the human Na X channel in complex with the auxiliary β3-subunit. Na X reveals structural alterations within the selectivity filter, voltage sensor-like domains, and pore module. We do not identify an extracellular Na + -sensor or any evidence for a Na + -based activation mechanism in Na X . Instead, the S6-gate remains closed, membrane lipids fill the central cavity, and the domain III-IV linker restricts S6-dilation. We use protein engineering to identify three pore-wetting mutations targeting the hydrophobic S6-gate that unlock a robust voltage-insensitive leak conductance. This constitutively active Na X -QTT channel construct is non-selective among monovalent cations, inhibited by extracellular calcium, and sensitive to classical Na V channel blockers, including tetrodotoxin. Our findings highlight a functional ersity across the Na V channel scaffold, reshape our understanding of Na X physiology, and provide a template to demystify recalcitrant ion channels.
Publisher: Springer Science and Business Media LLC
Date: 26-03-2018
DOI: 10.1007/S00392-018-1233-3
Abstract: Unexplained cardiac arrest (UCA) is often the first manifestation of an inherited arrhythmogenic disease. Genetic testing in UCA is challenging due to the complexities of variant interpretation in the absence of supporting cardiac phenotype. We aimed to investigate if a KCNQ1 variant [p.(Pro64_Pro70del)], previously reported as pathogenic, contributes to the long-QT syndrome phenotype, co-segregates with disease or affects KCNQ1 function in vitro. DNA was extracted from peripheral blood of a 22-year-old male after resuscitation from UCA. Targeted exome sequencing was performed using the TruSight-One Sequencing Panel (Illumina). Variants in 190 clinically relevant cardiac genes with minor allele frequency A in PKP2 (p.Arg811Ser), classified as likely benign. Two asymptomatic family members with no evident phenotype hosted the KCNQ1 variant. Functional studies showed that the wild-type and mutant channels have no significant differences in current levels, conductance-voltage relationships, as well as activation and deactivation kinetics, in the absence and presence of the auxiliary subunit KCNE1. Based on our data and previous reports, available evidence is insufficient to consider the variant KCNQ1:c.190_210del as pathogenic. Our findings call for cautious interpretation of genetic tests in UCA in the absence of a clinical phenotype.
Publisher: American Chemical Society (ACS)
Date: 29-01-2016
DOI: 10.1021/ACSCHEMNEURO.5B00298
Abstract: Cys-loop receptors mediate fast synaptic transmission in the nervous system, and their dysfunction is associated with a number of diseases. While some sequence variability is essential to ensure specific recognition of a chemically erse set of ligands, other parts of the underlying amino acid sequences show a high degree of conservation, possibly to preserve the overall structural fold across the protein family. In this study, we focus on the only two absolutely conserved residues across the Cys-loop receptor family, two Trp side chains in the WXD motif of Loop D and in the WXPD motif of Loop A. Using a combination of conventional mutagenesis, unnatural amino acid incorporation, immunohistochemistry and MD simulations, we demonstrate the crucial contributions of these two Trp residues to receptor expression and function in two prototypical Cys-loop receptors, the anion-selective GlyR α1 and the cation-selective nAChR α7. Specifically, our results rule out possible electrostatic contributions of these Trp side chains and instead suggest that the overall size and shape of this aromatic pair is required in stabilizing the Cys-loop receptor extracellular domain.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Springer Science and Business Media LLC
Date: 20-12-2021
DOI: 10.1038/S41586-021-04313-5
Abstract: Depolarizing sodium (Na
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 10-2021
DOI: 10.1016/J.NEUROPHARM.2021.108722
Abstract: Although several ionic mechanisms are known to control rate and regularity of the slow pacemaker in dopamine (DA) neurons, the core mechanism of pacing is controversial. Here we tested the hypothesis that pacemaking of SNc DA neurons is enabled by an unconventional conductance. We found that 1-(2,4-xylyl)guanidinium (XG), an established blocker of gating pore currents, selectively inhibits pacemaking of DA neurons. The compound inhibited all slow pacemaking DA neurons that were tested, both in the substantia nigra pars compacta, and in the ventral tegmental area. Interestingly, bursting behavior was not affected by XG. Furthermore, the drug did not affect fast pacemaking of GABAergic neurons from substantia nigra pars reticulata neurons or slow pacemaking of noradrenergic neurons. In DA neurons, current-cl analysis revealed that XG did not appear to affect ion channels involved in the action potential. Its inhibitory effect persisted during blockade of all ion channels previously suggested to contribute to pacemaking. RNA sequencing and voltage-cl recordings yielded no evidence for a gating pore current to underlie the conductance. However, we could isolate a small subthreshold XG-sensitive current, which was carried by both Na
Publisher: Elsevier BV
Date: 02-2023
Publisher: American Association for the Advancement of Science (AAAS)
Date: 24-04-2020
Abstract: NALCN is the voltage-sensing, pore-forming subunit of a constitutively active, extracellular calcium-regulated complex.
Publisher: Springer Science and Business Media LLC
Date: 22-07-2020
DOI: 10.1038/S41586-020-2570-8
Abstract: Persistently depolarizing sodium (Na
Publisher: Cold Spring Harbor Laboratory
Date: 02-02-2020
DOI: 10.1101/2020.01.31.925495
Abstract: Manipulation of proteins by chemical modification is a powerful way to decipher their function or harness that function for therapeutic purposes. Despite recent progress in ribosome-dependent and semi-synthetic chemical modifications, these techniques sometimes have limitations in the number and type of modifications that can be simultaneously introduced or their application in live eukaryotic cells. Here we present a new approach to incorporate single or multiple post-translational modifications or non-canonical amino acids into soluble and membrane proteins expressed in eukaryotic cells. We insert synthetic peptides into proteins of interest via tandem protein trans-splicing using two orthogonal split intein pairs and validate our approach by investigating different aspects of GFP, Na V 1.5 and P2X2 receptor function. Because the approach can introduce virtually any chemical modification into both intracellular and extracellular regions of target proteins, we anticipate that it will overcome some of the drawbacks of other semi-synthetic or ribosome-dependent methods to engineer proteins.
Publisher: Cold Spring Harbor Laboratory
Date: 13-04-2023
DOI: 10.1101/2023.04.12.536537
Abstract: The sodium (Na + ) leak channel (NALCN) is a member of the four-domain voltage-gated cation channel family that includes the prototypical voltage-gated sodium and calcium channels (Na V s and Ca V s, respectively). Unlike Na V s and Ca V s, which have four intramembrane fenestrations that serve as routes for lipophilic compounds to enter the central cavity to modulate channel function, NALCN has bulky residues (W311, L588, M1145 and Y1436) that block these openings. Structural data suggest that occluded lateral fenestrations underlie the pharmacological resistance of NALCN, but functional evidence is lacking. To test this hypothesis, we unplugged the fenestrations of NALCN by substituting the four aforementioned residues with alanine (AAAA) and compared the effects of Na V , Ca V and NALCN blockers on both wild-type (WT) and AAAA channels. Most compounds behaved in a similar manner on both channels, but phenytoin and 2-aminoethoxydiphenyl borate (2-APB) elicited additional, distinct responses on AAAA channels, highlighting the existence of drug binding sites beyond the occluded fenestrations of NALCN. Further experiments using single alanine mutants revealed that phenytoin and 2-APB access their putative binding sites through distinct fenestrations, implying structural specificity to their modes of access. Intrigued by the activity of 2-APB and its analogues, we tested more compounds containing the diphenylmethane/amine moiety on WT channels. We identified novel compounds that exhibited erse activity, thus expanding the pharmacological toolbox for NALCN. While the low potencies of active compounds reiterate the resistance of NALCN to pharmacological targeting, our findings lay the foundation for rational drug design to develop NALCN modulators with refined properties.
Publisher: Springer Science and Business Media LLC
Date: 08-05-2020
DOI: 10.1038/S41467-020-16208-6
Abstract: Manipulation of proteins by chemical modification is a powerful way to decipher their function. However, most ribosome-dependent and semi-synthetic methods have limitations in the number and type of modifications that can be introduced, especially in live cells. Here, we present an approach to incorporate single or multiple post-translational modifications or non-canonical amino acids into proteins expressed in eukaryotic cells. We insert synthetic peptides into GFP, Na V 1.5 and P2X2 receptors via tandem protein trans-splicing using two orthogonal split intein pairs and validate our approach by investigating protein function. We anticipate the approach will overcome some drawbacks of existing protein enigineering methods.
Start Date: 08-2022
End Date: 08-2025
Amount: $364,813.00
Funder: Australian Research Council
View Funded Activity