A high affinity switch for cAMP in the HCN pacemaker channels
Abstract Binding of cAMP to Hyperpolarization activated cyclic nucleotide gated (HCN) channels facilitates pore opening. It is unclear why the isolated cyclic nucleotide binding domain (CNBD) displays in vitro lower affinity for cAMP than the full-length channel in patch experiments. Here we show th...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Nature Portfolio
2024-01-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-024-45136-y |
| _version_ | 1797273950614454272 |
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| author | Alessandro Porro Andrea Saponaro Roberta Castelli Bianca Introini Anahita Hafez Alkotob Golnaz Ranjbari Uta Enke Jana Kusch Klaus Benndorf Bina Santoro Dario DiFrancesco Gerhard Thiel Anna Moroni |
| author_facet | Alessandro Porro Andrea Saponaro Roberta Castelli Bianca Introini Anahita Hafez Alkotob Golnaz Ranjbari Uta Enke Jana Kusch Klaus Benndorf Bina Santoro Dario DiFrancesco Gerhard Thiel Anna Moroni |
| author_sort | Alessandro Porro |
| collection | DOAJ |
| description | Abstract Binding of cAMP to Hyperpolarization activated cyclic nucleotide gated (HCN) channels facilitates pore opening. It is unclear why the isolated cyclic nucleotide binding domain (CNBD) displays in vitro lower affinity for cAMP than the full-length channel in patch experiments. Here we show that HCN are endowed with an affinity switch for cAMP. Alpha helices D and E, downstream of the cyclic nucleotide binding domain (CNBD), bind to and stabilize the holo CNBD in a high affinity state. These helices increase by 30-fold cAMP efficacy and affinity measured in patch clamp and ITC, respectively. We further show that helices D and E regulate affinity by interacting with helix C of the CNBD, similarly to the regulatory protein TRIP8b. Our results uncover an intramolecular mechanism whereby changes in binding affinity, rather than changes in cAMP concentration, can modulate HCN channels, adding another layer to the complex regulation of their activity. |
| first_indexed | 2024-03-07T14:51:26Z |
| format | Article |
| id | doaj.art-54ee296cfd5a4b9b8c10a343ba531e63 |
| institution | Directory Open Access Journal |
| issn | 2041-1723 |
| language | English |
| last_indexed | 2024-03-07T14:51:26Z |
| publishDate | 2024-01-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Nature Communications |
| spelling | doaj.art-54ee296cfd5a4b9b8c10a343ba531e632024-03-05T19:40:43ZengNature PortfolioNature Communications2041-17232024-01-0115111410.1038/s41467-024-45136-yA high affinity switch for cAMP in the HCN pacemaker channelsAlessandro Porro0Andrea Saponaro1Roberta Castelli2Bianca Introini3Anahita Hafez Alkotob4Golnaz Ranjbari5Uta Enke6Jana Kusch7Klaus Benndorf8Bina Santoro9Dario DiFrancesco10Gerhard Thiel11Anna Moroni12Department of Biosciences, University of MilanDepartment of Pharmacological and Biomolecular Sciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanDepartment of Biosciences, University of MilanInstitut für Physiologie II, Universitätsklinikum JenaInstitut für Physiologie II, Universitätsklinikum JenaInstitut für Physiologie II, Universitätsklinikum JenaDepartment of Neuroscience, Zuckerman Institute, Columbia UniversityDepartment of Biosciences, University of MilanDepartment of Biology, TU-DarmstadtDepartment of Biosciences, University of MilanAbstract Binding of cAMP to Hyperpolarization activated cyclic nucleotide gated (HCN) channels facilitates pore opening. It is unclear why the isolated cyclic nucleotide binding domain (CNBD) displays in vitro lower affinity for cAMP than the full-length channel in patch experiments. Here we show that HCN are endowed with an affinity switch for cAMP. Alpha helices D and E, downstream of the cyclic nucleotide binding domain (CNBD), bind to and stabilize the holo CNBD in a high affinity state. These helices increase by 30-fold cAMP efficacy and affinity measured in patch clamp and ITC, respectively. We further show that helices D and E regulate affinity by interacting with helix C of the CNBD, similarly to the regulatory protein TRIP8b. Our results uncover an intramolecular mechanism whereby changes in binding affinity, rather than changes in cAMP concentration, can modulate HCN channels, adding another layer to the complex regulation of their activity.https://doi.org/10.1038/s41467-024-45136-y |
| spellingShingle | Alessandro Porro Andrea Saponaro Roberta Castelli Bianca Introini Anahita Hafez Alkotob Golnaz Ranjbari Uta Enke Jana Kusch Klaus Benndorf Bina Santoro Dario DiFrancesco Gerhard Thiel Anna Moroni A high affinity switch for cAMP in the HCN pacemaker channels Nature Communications |
| title | A high affinity switch for cAMP in the HCN pacemaker channels |
| title_full | A high affinity switch for cAMP in the HCN pacemaker channels |
| title_fullStr | A high affinity switch for cAMP in the HCN pacemaker channels |
| title_full_unstemmed | A high affinity switch for cAMP in the HCN pacemaker channels |
| title_short | A high affinity switch for cAMP in the HCN pacemaker channels |
| title_sort | high affinity switch for camp in the hcn pacemaker channels |
| url | https://doi.org/10.1038/s41467-024-45136-y |
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