Cryo-EM structures of the TMEM16A calcium-activated chloride channel
Electron cryo-microscopy density maps of mouse TMEM16A reconstituted in nanodiscs or solubilized in detergent reveal two functional states of calcium-activated chloride channels. TMEM16A structure solved The diverse TMEM16 membrane protein family contains Ca( II )-activated chloride channels, lipid...
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| Veröffentlicht in: | Nature (London) 2017-12, Vol.552 (7685), p.426-429 |
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| creator | Dang, Shangyu Feng, Shengjie Tien, Jason Peters, Christian J. Bulkley, David Lolicato, Marco Zhao, Jianhua Zuberbühler, Kathrin Ye, Wenlei Qi, Lijun Chen, Tingxu Craik, Charles S. Jan, Yuh Nung Minor, Daniel L. Cheng, Yifan Jan, Lily Yeh |
| description | Electron cryo-microscopy density maps of mouse TMEM16A reconstituted in nanodiscs or solubilized in detergent reveal two functional states of calcium-activated chloride channels.
TMEM16A structure solved
The diverse TMEM16 membrane protein family contains Ca(
II
)-activated chloride channels, lipid scramblases and cation channels. TMEM16A mediates chloride-ion permeation, which controls neuronal signalling, muscle contraction and numerous other physiological functions. In this issue of
Nature
, two groups have solved the structure of TMEM16A by using cryo-electron microscopy, providing insights into the function of this channel. Unlike other ligand-gated ion channels, the Ca(
II
) ion interacts with the pore directly, where a glycine residue acts as a flexible hinge to adjust calcium sensitivity. Raimund Dutzler and colleagues report the structure of the protein in both Ca(
II
)-free and Ca(
II
)-bound states, which shows how calcium binding facilitates the structural rearrangements involved in channel activation. In the second Letter, Lily Jan and colleagues present two functional states of TMEM16A in the glycolipid LMNG and in nanodiscs, with one and two Ca(
II
) ions bound, respectively. The closed conformation observed in nanodiscs is proposed to show channel rundown after prolonged Ca(
II
) activation.
Calcium-activated chloride channels (CaCCs) encoded by TMEM16A
1
,
2
,
3
control neuronal signalling, smooth muscle contraction, airway and exocrine gland secretion, and rhythmic movements of the gastrointestinal system
4
,
5
,
6
,
7
. To understand how CaCCs mediate and control anion permeation to fulfil these physiological functions, knowledge of the mammalian TMEM16A structure and identification of its pore-lining residues are essential. TMEM16A forms a dimer with two pores
8
,
9
. Previous CaCC structural analyses have relied on homology modelling of a homologue (nhTMEM16) from the fungus
Nectria haematococca
that functions primarily as a lipid scramblase
10
,
11
,
12
, as well as subnanometre-resolution electron cryo-microscopy
12
. Here we present
de novo
atomic structures of the transmembrane domains of mouse TMEM16A in nanodiscs and in lauryl maltose neopentyl glycol as determined by single-particle electron cryo-microscopy. These structures reveal the ion permeation pore and represent different functional states. The structure in lauryl maltose neopentyl glycol has one Ca
2+
ion resolved within each monomer with a constricted pore; this is like |
| doi_str_mv | 10.1038/nature25024 |
| format | Article |
| fullrecord | <record><control><sourceid>gale_pubme</sourceid><recordid>TN_cdi_pubmedcentral_primary_oai_pubmedcentral_nih_gov_5750132</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><galeid>A521896609</galeid><sourcerecordid>A521896609</sourcerecordid><originalsourceid>FETCH-LOGICAL-c616t-f6d54c8213882acf07ab95ccc5b563c21746b629603fdf36b5036bbe476c2f3d3</originalsourceid><addsrcrecordid>eNp1kl2L1DAUhoMo7rh65b0UvRLtmo8mTW-EYRx1YUdBR7wM6WnSydKmY9Iu7r83y-gyA5VAEnKePCSHF6HnBF8QzOQ7r8cpGMoxLR6gBSlKkRdClg_RAmMqcyyZOENPYrzGGHNSFo_RGa0oE0IWC_RhFW6HfL3J4hgmuBPFbLDZuDPZdrPeELHMQHfgpj7XMLobPZomg103BNeYtNHem-4pemR1F82zv-s5-vFxvV19zq--frpcLa9yEESMuRUNL0BSwqSkGiwudV1xAOA1FwxoepuoBa0EZraxTNQcp6k26UdALWvYOXp_8O6nujcNGD8G3al9cL0Ot2rQTp1WvNupdrhRvOSYMJoErw6CVndGOW-HhEHvIqglp0RWQuAqUfkM1RpvknPwxrp0fMK_nOFh736pY-hiBkqjMb2DWevrkwuJGc3vsdVTjOry-7dT9s3_2eX25-rLLA1hiDEYe99BgtVdpNRRpBL94rjp9-y_DCXg7QGIqeRbE9T1MAWfgjDr-wMH8tKz</addsrcrecordid><sourcetype>Open Access Repository</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype></control><display><type>article</type><title>Cryo-EM structures of the TMEM16A calcium-activated chloride channel</title><source>MEDLINE</source><source>Nature</source><source>SpringerLink</source><creator>Dang, Shangyu ; Feng, Shengjie ; Tien, Jason ; Peters, Christian J. ; Bulkley, David ; Lolicato, Marco ; Zhao, Jianhua ; Zuberbühler, Kathrin ; Ye, Wenlei ; Qi, Lijun ; Chen, Tingxu ; Craik, Charles S. ; Jan, Yuh Nung ; Minor, Daniel L. ; Cheng, Yifan ; Jan, Lily Yeh</creator><creatorcontrib>Dang, Shangyu ; Feng, Shengjie ; Tien, Jason ; Peters, Christian J. ; Bulkley, David ; Lolicato, Marco ; Zhao, Jianhua ; Zuberbühler, Kathrin ; Ye, Wenlei ; Qi, Lijun ; Chen, Tingxu ; Craik, Charles S. ; Jan, Yuh Nung ; Minor, Daniel L. ; Cheng, Yifan ; Jan, Lily Yeh</creatorcontrib><description>Electron cryo-microscopy density maps of mouse TMEM16A reconstituted in nanodiscs or solubilized in detergent reveal two functional states of calcium-activated chloride channels.
TMEM16A structure solved
The diverse TMEM16 membrane protein family contains Ca(
II
)-activated chloride channels, lipid scramblases and cation channels. TMEM16A mediates chloride-ion permeation, which controls neuronal signalling, muscle contraction and numerous other physiological functions. In this issue of
Nature
, two groups have solved the structure of TMEM16A by using cryo-electron microscopy, providing insights into the function of this channel. Unlike other ligand-gated ion channels, the Ca(
II
) ion interacts with the pore directly, where a glycine residue acts as a flexible hinge to adjust calcium sensitivity. Raimund Dutzler and colleagues report the structure of the protein in both Ca(
II
)-free and Ca(
II
)-bound states, which shows how calcium binding facilitates the structural rearrangements involved in channel activation. In the second Letter, Lily Jan and colleagues present two functional states of TMEM16A in the glycolipid LMNG and in nanodiscs, with one and two Ca(
II
) ions bound, respectively. The closed conformation observed in nanodiscs is proposed to show channel rundown after prolonged Ca(
II
) activation.
Calcium-activated chloride channels (CaCCs) encoded by TMEM16A
1
,
2
,
3
control neuronal signalling, smooth muscle contraction, airway and exocrine gland secretion, and rhythmic movements of the gastrointestinal system
4
,
5
,
6
,
7
. To understand how CaCCs mediate and control anion permeation to fulfil these physiological functions, knowledge of the mammalian TMEM16A structure and identification of its pore-lining residues are essential. TMEM16A forms a dimer with two pores
8
,
9
. Previous CaCC structural analyses have relied on homology modelling of a homologue (nhTMEM16) from the fungus
Nectria haematococca
that functions primarily as a lipid scramblase
10
,
11
,
12
, as well as subnanometre-resolution electron cryo-microscopy
12
. Here we present
de novo
atomic structures of the transmembrane domains of mouse TMEM16A in nanodiscs and in lauryl maltose neopentyl glycol as determined by single-particle electron cryo-microscopy. These structures reveal the ion permeation pore and represent different functional states. The structure in lauryl maltose neopentyl glycol has one Ca
2+
ion resolved within each monomer with a constricted pore; this is likely to correspond to a closed state, because a CaCC with a single Ca
2+
occupancy requires membrane depolarization in order to open (C.J.P.
et al
., manuscript submitted). The structure in nanodiscs has two Ca
2+
ions per monomer and its pore is in a closed conformation; this probably reflects channel rundown, which is the gradual loss of channel activity that follows prolonged CaCC activation in 1 mM Ca
2+
. Our mutagenesis and electrophysiological studies, prompted by analyses of the structures, identified ten residues distributed along the pore that interact with permeant anions and affect anion selectivity, as well as seven pore-lining residues that cluster near pore constrictions and regulate channel gating. Together, these results clarify the basis of CaCC anion conduction.</description><identifier>ISSN: 0028-0836</identifier><identifier>EISSN: 1476-4687</identifier><identifier>DOI: 10.1038/nature25024</identifier><identifier>PMID: 29236684</identifier><language>eng</language><publisher>London: Nature Publishing Group UK</publisher><subject>101/28 ; 631/535/1258/1259 ; 631/57/2270/1140 ; 82 ; 82/1 ; 82/80 ; 82/83 ; 9/74 ; Analysis ; Animals ; Anions - chemistry ; Anions - metabolism ; Anoctamin-1 - chemistry ; Anoctamin-1 - metabolism ; Anoctamin-1 - ultrastructure ; Calcium - chemistry ; Calcium - metabolism ; Calcium - pharmacology ; Cell receptors ; Chloride channels ; Cryoelectron Microscopy ; Glucosides - chemistry ; HEK293 Cells ; Humanities and Social Sciences ; Humans ; Ion Channel Gating - drug effects ; Ion Transport - drug effects ; letter ; Mice ; Models, Molecular ; multidisciplinary ; Nanostructures - chemistry ; Nanostructures - ultrastructure ; Protein Conformation - drug effects ; Science</subject><ispartof>Nature (London), 2017-12, Vol.552 (7685), p.426-429</ispartof><rights>Macmillan Publishers Limited, part of Springer Nature. All rights reserved. 2017</rights><rights>COPYRIGHT 2017 Nature Publishing Group</rights><lds50>peer_reviewed</lds50><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c616t-f6d54c8213882acf07ab95ccc5b563c21746b629603fdf36b5036bbe476c2f3d3</citedby><cites>FETCH-LOGICAL-c616t-f6d54c8213882acf07ab95ccc5b563c21746b629603fdf36b5036bbe476c2f3d3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktopdf>$$Uhttps://link.springer.com/content/pdf/10.1038/nature25024$$EPDF$$P50$$Gspringer$$H</linktopdf><linktohtml>$$Uhttps://link.springer.com/10.1038/nature25024$$EHTML$$P50$$Gspringer$$H</linktohtml><link.rule.ids>230,314,776,780,881,27903,27904,41467,42536,51298</link.rule.ids><backlink>$$Uhttps://www.ncbi.nlm.nih.gov/pubmed/29236684$$D View this record in MEDLINE/PubMed$$Hfree_for_read</backlink></links><search><creatorcontrib>Dang, Shangyu</creatorcontrib><creatorcontrib>Feng, Shengjie</creatorcontrib><creatorcontrib>Tien, Jason</creatorcontrib><creatorcontrib>Peters, Christian J.</creatorcontrib><creatorcontrib>Bulkley, David</creatorcontrib><creatorcontrib>Lolicato, Marco</creatorcontrib><creatorcontrib>Zhao, Jianhua</creatorcontrib><creatorcontrib>Zuberbühler, Kathrin</creatorcontrib><creatorcontrib>Ye, Wenlei</creatorcontrib><creatorcontrib>Qi, Lijun</creatorcontrib><creatorcontrib>Chen, Tingxu</creatorcontrib><creatorcontrib>Craik, Charles S.</creatorcontrib><creatorcontrib>Jan, Yuh Nung</creatorcontrib><creatorcontrib>Minor, Daniel L.</creatorcontrib><creatorcontrib>Cheng, Yifan</creatorcontrib><creatorcontrib>Jan, Lily Yeh</creatorcontrib><title>Cryo-EM structures of the TMEM16A calcium-activated chloride channel</title><title>Nature (London)</title><addtitle>Nature</addtitle><addtitle>Nature</addtitle><description>Electron cryo-microscopy density maps of mouse TMEM16A reconstituted in nanodiscs or solubilized in detergent reveal two functional states of calcium-activated chloride channels.
TMEM16A structure solved
The diverse TMEM16 membrane protein family contains Ca(
II
)-activated chloride channels, lipid scramblases and cation channels. TMEM16A mediates chloride-ion permeation, which controls neuronal signalling, muscle contraction and numerous other physiological functions. In this issue of
Nature
, two groups have solved the structure of TMEM16A by using cryo-electron microscopy, providing insights into the function of this channel. Unlike other ligand-gated ion channels, the Ca(
II
) ion interacts with the pore directly, where a glycine residue acts as a flexible hinge to adjust calcium sensitivity. Raimund Dutzler and colleagues report the structure of the protein in both Ca(
II
)-free and Ca(
II
)-bound states, which shows how calcium binding facilitates the structural rearrangements involved in channel activation. In the second Letter, Lily Jan and colleagues present two functional states of TMEM16A in the glycolipid LMNG and in nanodiscs, with one and two Ca(
II
) ions bound, respectively. The closed conformation observed in nanodiscs is proposed to show channel rundown after prolonged Ca(
II
) activation.
Calcium-activated chloride channels (CaCCs) encoded by TMEM16A
1
,
2
,
3
control neuronal signalling, smooth muscle contraction, airway and exocrine gland secretion, and rhythmic movements of the gastrointestinal system
4
,
5
,
6
,
7
. To understand how CaCCs mediate and control anion permeation to fulfil these physiological functions, knowledge of the mammalian TMEM16A structure and identification of its pore-lining residues are essential. TMEM16A forms a dimer with two pores
8
,
9
. Previous CaCC structural analyses have relied on homology modelling of a homologue (nhTMEM16) from the fungus
Nectria haematococca
that functions primarily as a lipid scramblase
10
,
11
,
12
, as well as subnanometre-resolution electron cryo-microscopy
12
. Here we present
de novo
atomic structures of the transmembrane domains of mouse TMEM16A in nanodiscs and in lauryl maltose neopentyl glycol as determined by single-particle electron cryo-microscopy. These structures reveal the ion permeation pore and represent different functional states. The structure in lauryl maltose neopentyl glycol has one Ca
2+
ion resolved within each monomer with a constricted pore; this is likely to correspond to a closed state, because a CaCC with a single Ca
2+
occupancy requires membrane depolarization in order to open (C.J.P.
et al
., manuscript submitted). The structure in nanodiscs has two Ca
2+
ions per monomer and its pore is in a closed conformation; this probably reflects channel rundown, which is the gradual loss of channel activity that follows prolonged CaCC activation in 1 mM Ca
2+
. Our mutagenesis and electrophysiological studies, prompted by analyses of the structures, identified ten residues distributed along the pore that interact with permeant anions and affect anion selectivity, as well as seven pore-lining residues that cluster near pore constrictions and regulate channel gating. Together, these results clarify the basis of CaCC anion conduction.</description><subject>101/28</subject><subject>631/535/1258/1259</subject><subject>631/57/2270/1140</subject><subject>82</subject><subject>82/1</subject><subject>82/80</subject><subject>82/83</subject><subject>9/74</subject><subject>Analysis</subject><subject>Animals</subject><subject>Anions - chemistry</subject><subject>Anions - metabolism</subject><subject>Anoctamin-1 - chemistry</subject><subject>Anoctamin-1 - metabolism</subject><subject>Anoctamin-1 - ultrastructure</subject><subject>Calcium - chemistry</subject><subject>Calcium - metabolism</subject><subject>Calcium - pharmacology</subject><subject>Cell receptors</subject><subject>Chloride channels</subject><subject>Cryoelectron Microscopy</subject><subject>Glucosides - chemistry</subject><subject>HEK293 Cells</subject><subject>Humanities and Social Sciences</subject><subject>Humans</subject><subject>Ion Channel Gating - drug effects</subject><subject>Ion Transport - drug effects</subject><subject>letter</subject><subject>Mice</subject><subject>Models, Molecular</subject><subject>multidisciplinary</subject><subject>Nanostructures - chemistry</subject><subject>Nanostructures - ultrastructure</subject><subject>Protein Conformation - drug effects</subject><subject>Science</subject><issn>0028-0836</issn><issn>1476-4687</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2017</creationdate><recordtype>article</recordtype><sourceid>EIF</sourceid><recordid>eNp1kl2L1DAUhoMo7rh65b0UvRLtmo8mTW-EYRx1YUdBR7wM6WnSydKmY9Iu7r83y-gyA5VAEnKePCSHF6HnBF8QzOQ7r8cpGMoxLR6gBSlKkRdClg_RAmMqcyyZOENPYrzGGHNSFo_RGa0oE0IWC_RhFW6HfL3J4hgmuBPFbLDZuDPZdrPeELHMQHfgpj7XMLobPZomg103BNeYtNHem-4pemR1F82zv-s5-vFxvV19zq--frpcLa9yEESMuRUNL0BSwqSkGiwudV1xAOA1FwxoepuoBa0EZraxTNQcp6k26UdALWvYOXp_8O6nujcNGD8G3al9cL0Ot2rQTp1WvNupdrhRvOSYMJoErw6CVndGOW-HhEHvIqglp0RWQuAqUfkM1RpvknPwxrp0fMK_nOFh736pY-hiBkqjMb2DWevrkwuJGc3vsdVTjOry-7dT9s3_2eX25-rLLA1hiDEYe99BgtVdpNRRpBL94rjp9-y_DCXg7QGIqeRbE9T1MAWfgjDr-wMH8tKz</recordid><startdate>20171221</startdate><enddate>20171221</enddate><creator>Dang, Shangyu</creator><creator>Feng, Shengjie</creator><creator>Tien, Jason</creator><creator>Peters, Christian J.</creator><creator>Bulkley, David</creator><creator>Lolicato, Marco</creator><creator>Zhao, Jianhua</creator><creator>Zuberbühler, Kathrin</creator><creator>Ye, Wenlei</creator><creator>Qi, Lijun</creator><creator>Chen, Tingxu</creator><creator>Craik, Charles S.</creator><creator>Jan, Yuh Nung</creator><creator>Minor, Daniel L.</creator><creator>Cheng, Yifan</creator><creator>Jan, Lily Yeh</creator><general>Nature Publishing Group UK</general><general>Nature Publishing Group</general><scope>CGR</scope><scope>CUY</scope><scope>CVF</scope><scope>ECM</scope><scope>EIF</scope><scope>NPM</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>ATWCN</scope><scope>5PM</scope></search><sort><creationdate>20171221</creationdate><title>Cryo-EM structures of the TMEM16A calcium-activated chloride channel</title><author>Dang, Shangyu ; Feng, Shengjie ; Tien, Jason ; Peters, Christian J. ; Bulkley, David ; Lolicato, Marco ; Zhao, Jianhua ; Zuberbühler, Kathrin ; Ye, Wenlei ; Qi, Lijun ; Chen, Tingxu ; Craik, Charles S. ; Jan, Yuh Nung ; Minor, Daniel L. ; Cheng, Yifan ; Jan, Lily Yeh</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c616t-f6d54c8213882acf07ab95ccc5b563c21746b629603fdf36b5036bbe476c2f3d3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2017</creationdate><topic>101/28</topic><topic>631/535/1258/1259</topic><topic>631/57/2270/1140</topic><topic>82</topic><topic>82/1</topic><topic>82/80</topic><topic>82/83</topic><topic>9/74</topic><topic>Analysis</topic><topic>Animals</topic><topic>Anions - chemistry</topic><topic>Anions - metabolism</topic><topic>Anoctamin-1 - chemistry</topic><topic>Anoctamin-1 - metabolism</topic><topic>Anoctamin-1 - ultrastructure</topic><topic>Calcium - chemistry</topic><topic>Calcium - metabolism</topic><topic>Calcium - pharmacology</topic><topic>Cell receptors</topic><topic>Chloride channels</topic><topic>Cryoelectron Microscopy</topic><topic>Glucosides - chemistry</topic><topic>HEK293 Cells</topic><topic>Humanities and Social Sciences</topic><topic>Humans</topic><topic>Ion Channel Gating - drug effects</topic><topic>Ion Transport - drug effects</topic><topic>letter</topic><topic>Mice</topic><topic>Models, Molecular</topic><topic>multidisciplinary</topic><topic>Nanostructures - chemistry</topic><topic>Nanostructures - ultrastructure</topic><topic>Protein Conformation - drug effects</topic><topic>Science</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Dang, Shangyu</creatorcontrib><creatorcontrib>Feng, Shengjie</creatorcontrib><creatorcontrib>Tien, Jason</creatorcontrib><creatorcontrib>Peters, Christian J.</creatorcontrib><creatorcontrib>Bulkley, David</creatorcontrib><creatorcontrib>Lolicato, Marco</creatorcontrib><creatorcontrib>Zhao, Jianhua</creatorcontrib><creatorcontrib>Zuberbühler, Kathrin</creatorcontrib><creatorcontrib>Ye, Wenlei</creatorcontrib><creatorcontrib>Qi, Lijun</creatorcontrib><creatorcontrib>Chen, Tingxu</creatorcontrib><creatorcontrib>Craik, Charles S.</creatorcontrib><creatorcontrib>Jan, Yuh Nung</creatorcontrib><creatorcontrib>Minor, Daniel L.</creatorcontrib><creatorcontrib>Cheng, Yifan</creatorcontrib><creatorcontrib>Jan, Lily Yeh</creatorcontrib><collection>Medline</collection><collection>MEDLINE</collection><collection>MEDLINE (Ovid)</collection><collection>MEDLINE</collection><collection>MEDLINE</collection><collection>PubMed</collection><collection>CrossRef</collection><collection>Gale In Context: Middle School</collection><collection>PubMed Central (Full Participant titles)</collection><jtitle>Nature (London)</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Dang, Shangyu</au><au>Feng, Shengjie</au><au>Tien, Jason</au><au>Peters, Christian J.</au><au>Bulkley, David</au><au>Lolicato, Marco</au><au>Zhao, Jianhua</au><au>Zuberbühler, Kathrin</au><au>Ye, Wenlei</au><au>Qi, Lijun</au><au>Chen, Tingxu</au><au>Craik, Charles S.</au><au>Jan, Yuh Nung</au><au>Minor, Daniel L.</au><au>Cheng, Yifan</au><au>Jan, Lily Yeh</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Cryo-EM structures of the TMEM16A calcium-activated chloride channel</atitle><jtitle>Nature (London)</jtitle><stitle>Nature</stitle><addtitle>Nature</addtitle><date>2017-12-21</date><risdate>2017</risdate><volume>552</volume><issue>7685</issue><spage>426</spage><epage>429</epage><pages>426-429</pages><issn>0028-0836</issn><eissn>1476-4687</eissn><abstract>Electron cryo-microscopy density maps of mouse TMEM16A reconstituted in nanodiscs or solubilized in detergent reveal two functional states of calcium-activated chloride channels.
TMEM16A structure solved
The diverse TMEM16 membrane protein family contains Ca(
II
)-activated chloride channels, lipid scramblases and cation channels. TMEM16A mediates chloride-ion permeation, which controls neuronal signalling, muscle contraction and numerous other physiological functions. In this issue of
Nature
, two groups have solved the structure of TMEM16A by using cryo-electron microscopy, providing insights into the function of this channel. Unlike other ligand-gated ion channels, the Ca(
II
) ion interacts with the pore directly, where a glycine residue acts as a flexible hinge to adjust calcium sensitivity. Raimund Dutzler and colleagues report the structure of the protein in both Ca(
II
)-free and Ca(
II
)-bound states, which shows how calcium binding facilitates the structural rearrangements involved in channel activation. In the second Letter, Lily Jan and colleagues present two functional states of TMEM16A in the glycolipid LMNG and in nanodiscs, with one and two Ca(
II
) ions bound, respectively. The closed conformation observed in nanodiscs is proposed to show channel rundown after prolonged Ca(
II
) activation.
Calcium-activated chloride channels (CaCCs) encoded by TMEM16A
1
,
2
,
3
control neuronal signalling, smooth muscle contraction, airway and exocrine gland secretion, and rhythmic movements of the gastrointestinal system
4
,
5
,
6
,
7
. To understand how CaCCs mediate and control anion permeation to fulfil these physiological functions, knowledge of the mammalian TMEM16A structure and identification of its pore-lining residues are essential. TMEM16A forms a dimer with two pores
8
,
9
. Previous CaCC structural analyses have relied on homology modelling of a homologue (nhTMEM16) from the fungus
Nectria haematococca
that functions primarily as a lipid scramblase
10
,
11
,
12
, as well as subnanometre-resolution electron cryo-microscopy
12
. Here we present
de novo
atomic structures of the transmembrane domains of mouse TMEM16A in nanodiscs and in lauryl maltose neopentyl glycol as determined by single-particle electron cryo-microscopy. These structures reveal the ion permeation pore and represent different functional states. The structure in lauryl maltose neopentyl glycol has one Ca
2+
ion resolved within each monomer with a constricted pore; this is likely to correspond to a closed state, because a CaCC with a single Ca
2+
occupancy requires membrane depolarization in order to open (C.J.P.
et al
., manuscript submitted). The structure in nanodiscs has two Ca
2+
ions per monomer and its pore is in a closed conformation; this probably reflects channel rundown, which is the gradual loss of channel activity that follows prolonged CaCC activation in 1 mM Ca
2+
. Our mutagenesis and electrophysiological studies, prompted by analyses of the structures, identified ten residues distributed along the pore that interact with permeant anions and affect anion selectivity, as well as seven pore-lining residues that cluster near pore constrictions and regulate channel gating. Together, these results clarify the basis of CaCC anion conduction.</abstract><cop>London</cop><pub>Nature Publishing Group UK</pub><pmid>29236684</pmid><doi>10.1038/nature25024</doi><tpages>4</tpages><oa>free_for_read</oa></addata></record> |
| fulltext | fulltext |
| identifier | ISSN: 0028-0836 |
| ispartof | Nature (London), 2017-12, Vol.552 (7685), p.426-429 |
| issn | 0028-0836 1476-4687 |
| language | eng |
| recordid | cdi_pubmedcentral_primary_oai_pubmedcentral_nih_gov_5750132 |
| source | MEDLINE; Nature; SpringerLink |
| subjects | 101/28 631/535/1258/1259 631/57/2270/1140 82 82/1 82/80 82/83 9/74 Analysis Animals Anions - chemistry Anions - metabolism Anoctamin-1 - chemistry Anoctamin-1 - metabolism Anoctamin-1 - ultrastructure Calcium - chemistry Calcium - metabolism Calcium - pharmacology Cell receptors Chloride channels Cryoelectron Microscopy Glucosides - chemistry HEK293 Cells Humanities and Social Sciences Humans Ion Channel Gating - drug effects Ion Transport - drug effects letter Mice Models, Molecular multidisciplinary Nanostructures - chemistry Nanostructures - ultrastructure Protein Conformation - drug effects Science |
| title | Cryo-EM structures of the TMEM16A calcium-activated chloride channel |
| url | https://sfx.bib-bvb.de/sfx_tum?ctx_ver=Z39.88-2004&ctx_enc=info:ofi/enc:UTF-8&ctx_tim=2025-01-22T14%3A50%3A28IST&url_ver=Z39.88-2004&url_ctx_fmt=infofi/fmt:kev:mtx:ctx&rfr_id=info:sid/primo.exlibrisgroup.com:primo3-Article-gale_pubme&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.atitle=Cryo-EM%20structures%20of%20the%20TMEM16A%20calcium-activated%20chloride%20channel&rft.jtitle=Nature%20(London)&rft.au=Dang,%20Shangyu&rft.date=2017-12-21&rft.volume=552&rft.issue=7685&rft.spage=426&rft.epage=429&rft.pages=426-429&rft.issn=0028-0836&rft.eissn=1476-4687&rft_id=info:doi/10.1038/nature25024&rft_dat=%3Cgale_pubme%3EA521896609%3C/gale_pubme%3E%3Curl%3E%3C/url%3E&disable_directlink=true&sfx.directlink=off&sfx.report_link=0&rft_id=info:oai/&rft_id=info:pmid/29236684&rft_galeid=A521896609&rfr_iscdi=true |