Dataset Information

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn²⁺ ions.

ABSTRACT: Toll-like receptors (TLRs) play an important role in the innate immune response. While a lot is known about the structures of their extracellular parts, many questions are still left unanswered, when the structural basis of TLR activation is analyzed for the TLR intracellular domains. Here we report the structure and dynamics of TLR1 toll-interleukin like (TIR) cytoplasmic domain in crystal and in solution. We found that the TLR1-TIR domain is capable of specific binding of Zn with nanomolar affinity. Interactions with Zn are mediated by cysteine residues 667 and 686 and C667 is essential for the Zn binding. Potential structures of the TLR1-TIR/Zn complex were predicted in silico. Using the functional assays for the heterodimeric TLR1/2 receptor, we found that both Zn addition and Zn depletion affect the activity of TLR1, and C667A mutation disrupts the receptor activity. Analysis of C667 position in the TLR1 structure and possible effects of C667A mutation, suggests that zinc-binding ability of TLR1-TIR domain is critical for the receptor activation.

SUBMITTER: Lushpa VA

PROVIDER: S-EPMC8385042 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Publications

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn<sup>2+</sup> ions.

Lushpa Vladislav A VA Goncharuk Marina V MV Lin Cong C Zalevsky Arthur O AO Talyzina Irina A IA Luginina Aleksandra P AP Vakhrameev Daniil D DD Shevtsov Mikhail B MB Goncharuk Sergey A SA Arseniev Alexander S AS Borshchevskiy Valentin I VI Wang Xiaohui X Mineev Konstantin S KS

Communications biology 20210824 1

Toll-like receptors (TLRs) play an important role in the innate immune response. While a lot is known about the structures of their extracellular parts, many questions are still left unanswered, when the structural basis of TLR activation is analyzed for the TLR intracellular domains. Here we report the structure and dynamics of TLR1 toll-interleukin like (TIR) cytoplasmic domain in crystal and in solution. We found that the TLR1-TIR domain is capable of specific binding of Zn with nanomolar aff ...[more]

PMID: 34429510

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Project description:Electrical synapses between neurons in the mammalian CNS are predominantly formed of the connexin36 (Cx36) gap junction (GJ) channel protein. Unique among GJs formed of a number of other members of the Cx gene family, Cx36 GJs possess a high sensitivity to intracellular Mg2+ that can robustly act to modulate the strength of electrical synaptic transmission. Although a putative Mg2+ binding site was previously identified to reside in the aqueous pore in the first extracellular (E1) loop domain, the involvement of the N-terminal (NT) domain in the atypical response of Cx36 GJs to pH was shown to depend on intracellular levels of Mg2+. In this study, we examined the impact of amino acid substitutions in the NT domain on Mg2+ modulation of Cx36 GJs, focusing on positions predicted to line the pore funnel, which constitutes the cytoplasmic entrance of the channel pore. We find that charge substitutions at the 8th, 13th, and 18th positions had pronounced effects on Mg2+ sensitivity, particularly at position 13 at which an A13K substitution completely abolished sensitivity to Mg2+. To assess potential mechanisms of Mg2+ action, we constructed and tested a series of mathematical models that took into account gating of the component hemichannels in a Cx36 GJ channel as well as Mg2+ binding to each hemichannel in open and/or closed states. Simultaneous model fitting of measurements of junctional conductance, gj, and transjunctional Mg2+ fluxes using a fluorescent Mg2+ indicator suggested that the most viable mechanism for Cx36 regulation by Mg2+ entails the binding of Mg2+ to and subsequent stabilization of the closed state in each hemichannel. Reduced permeability to Mg2+ was also evident, particularly for the A13K substitution, but homology modeling of all charge-substituted NT variants showed only a moderate correlation between a reduction in the negative electrostatic potential and a reduction in the permeability to Mg2+ ions. Given the reported role of the E1 domain in Mg2+ binding together with the impact of NT substitutions on gating and the apparent state-dependence of Mg2+ binding, this study suggests that the NT domain can be an integral part of Mg2+ modulation of Cx36 GJs likely through the coupling of conformational changes between NT and E1 domains.

Dataset Information

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn²⁺ ions.

Publications

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn<sup>2+</sup> ions.

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Dataset Information

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn2+ ions.

Publications

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn<sup>2+</sup> ions.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Modulation of Toll-like receptor 1 intracellular domain structure and activity by Zn²⁺ ions.