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Conference Paper: Dynamic conformational changes of the P-S6 linker of the pacemaker (HCN) channels identified by sulfhydryl modification: pore-to-gate coupling model

TitleDynamic conformational changes of the P-S6 linker of the pacemaker (HCN) channels identified by sulfhydryl modification: pore-to-gate coupling model
Authors
Issue Date2008
PublisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/heartrhythmjournal
Citation
The 29th Annual Scientific Session of the Heart Rhythm Society (Heart Rhythm 2008), San Francisco, CA., 14-17 May 2008. In Heart Rhythm, v. 5 n. 5 suppl., p. S260, abstract no. PO4-5 How to Cite?
AbstractINTRODUCTION: The hyperpolarization-activated cyclic nucleotidemodulated (HCN) channel gene family encodes the funny current, a key player of cardiac pacing. Although the topology of HCN channels resembles voltage-gated potassium (Kv) channels, much less is known about their structure-function correlation. We have recently reported various lines of biophysical evidence that supports an evolutionary conserved external pore-to-gate mechanism of HCN channels despite their activation by opposite voltages. METHODS: Here we probed the P-S6 region of HCN1 channels homologous to external pore helix of KcsA potassium channel by cysteine scanning mutagenesis and hydrophilic sulfhydrylreactive 2-trimethylammoniumethylmethane thiosulfonate (MTSET). RESULTS: The introduced cysteines at position 353 and 354, which are closest to the GYG motif, were accessible by external MTSET, which led to reductions in whole cell current for 72 % and 41 % respectively. These reductions in whole cell currents were primarily resulted from negative shift in the activation gating, $V½ ~ -24 mV in Q353C and ~ -9 mV in A354C. More importantly, the MTSET reactivity were state-dependent suggestive of dynamic conformational change of this outer pore structure. These data were in accord with the notion that hindered pore movements affect gating. Interestingly, two other cysteine residues (S357C and M358C) closest to the S6 exhibited no observable effects to MTSET. CONCLUSIONS: We conclude that residues of immediate vicinity of the GYG motif in P-S6 loops of HCN1 channels exhibit statedependent external accessibility to MTSET and that the external pore vestibule and the activation gating of HCN channels are allosterically coupled.
DescriptionPoster Session 4: no. PO4-5
Persistent Identifierhttp://hdl.handle.net/10722/101412
ISSN
2015 Impact Factor: 4.391
2015 SCImago Journal Rankings: 2.756

 

DC FieldValueLanguage
dc.contributor.authorSiu, DCWen_HK
dc.contributor.authorAu, KWen_HK
dc.contributor.authorLau, CPen_HK
dc.contributor.authorTse, HFen_HK
dc.contributor.authorLi, RAen_HK
dc.date.accessioned2010-09-25T19:48:37Z-
dc.date.available2010-09-25T19:48:37Z-
dc.date.issued2008en_HK
dc.identifier.citationThe 29th Annual Scientific Session of the Heart Rhythm Society (Heart Rhythm 2008), San Francisco, CA., 14-17 May 2008. In Heart Rhythm, v. 5 n. 5 suppl., p. S260, abstract no. PO4-5-
dc.identifier.issn1547-5271-
dc.identifier.urihttp://hdl.handle.net/10722/101412-
dc.descriptionPoster Session 4: no. PO4-5-
dc.description.abstractINTRODUCTION: The hyperpolarization-activated cyclic nucleotidemodulated (HCN) channel gene family encodes the funny current, a key player of cardiac pacing. Although the topology of HCN channels resembles voltage-gated potassium (Kv) channels, much less is known about their structure-function correlation. We have recently reported various lines of biophysical evidence that supports an evolutionary conserved external pore-to-gate mechanism of HCN channels despite their activation by opposite voltages. METHODS: Here we probed the P-S6 region of HCN1 channels homologous to external pore helix of KcsA potassium channel by cysteine scanning mutagenesis and hydrophilic sulfhydrylreactive 2-trimethylammoniumethylmethane thiosulfonate (MTSET). RESULTS: The introduced cysteines at position 353 and 354, which are closest to the GYG motif, were accessible by external MTSET, which led to reductions in whole cell current for 72 % and 41 % respectively. These reductions in whole cell currents were primarily resulted from negative shift in the activation gating, $V½ ~ -24 mV in Q353C and ~ -9 mV in A354C. More importantly, the MTSET reactivity were state-dependent suggestive of dynamic conformational change of this outer pore structure. These data were in accord with the notion that hindered pore movements affect gating. Interestingly, two other cysteine residues (S357C and M358C) closest to the S6 exhibited no observable effects to MTSET. CONCLUSIONS: We conclude that residues of immediate vicinity of the GYG motif in P-S6 loops of HCN1 channels exhibit statedependent external accessibility to MTSET and that the external pore vestibule and the activation gating of HCN channels are allosterically coupled.-
dc.languageengen_HK
dc.publisherElsevier Inc. The Journal's web site is located at http://www.elsevier.com/locate/heartrhythmjournal-
dc.relation.ispartofHeart Rhythm-
dc.titleDynamic conformational changes of the P-S6 linker of the pacemaker (HCN) channels identified by sulfhydryl modification: pore-to-gate coupling modelen_HK
dc.typeConference_Paperen_HK
dc.identifier.emailSiu, DCW: cwdsiu@hkucc.hku.hken_HK
dc.identifier.doi10.1016/j.hrthm.2008.03.049-
dc.identifier.hkuros161485en_HK
dc.identifier.hkuros146676-
dc.identifier.volume5-
dc.identifier.issue5 suppl.-
dc.identifier.spageS260, abstract no. PO4-5-
dc.identifier.epageS260, abstract no. PO4-5-
dc.publisher.placeUnited States-

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