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Article: Membrane-inserted conformation of transmembrane domain 4 of divalent-metal transporter

TitleMembrane-inserted conformation of transmembrane domain 4 of divalent-metal transporter
Authors
KeywordsCircular dichroism (CD)
Detergent
Divalent-metal transporter 1 (DMT1)
NMR
Phospholipid vesicles
Secondary structure
Issue Date2003
PublisherPortland Press Ltd. The Journal's web site is located at http://www.biochemj.org
Citation
Biochemical Journal, 2003, v. 372 n. 3, p. 757-766 How to Cite?
AbstractDivalent-metal transporter 1 (DMT1) is involved in the intestinal iron absorption and in iron transport in the transferrin cycle, It transports metal ions at low pH (≈ 5.5), but not at high pH (7.4), and the transport is a proton-coupled process. Previously it has been shown that transmembrane domain 4 (TM4) is crucial for the function of this protein. Here we provide the first direct experimental evidence for secondary-structural features and membrane insertions of a 24-residue peptide, corresponding to TM4 of DMT1 (DMT1-TM4), in various membrane-mimicking environments by the combined use of CD and NMR spectroscopies. The peptide mainly adopts an α-helical structure in trifluoroethanol, SDS and dodecylphosphocholine micelles, and dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol small unilamellar vesicles. It has been demonstrated from both Hα secondary shifts and nuclear-Overhauser-enhancement (NOE) connectivities that the peptide is well folded into an a-helix from Val 8 to Lys 23 in SDS micelles at pH 4.0, whereas the N-terminus is highly flexible. The α-helical content estimated from NMR data is in agreement with that extracted from CD simulations. The highest helicity was observed in the anionic phospholipids {1,2-dimyristoyl-sn-glycero-3-[phosphorac-(1-glycerol)]}, indicating that electrostatic attraction is important for peptide binding and insertion into the membranes. The secondary-structural transition of the peptide occurred at pH 4.3 in the 2,2,2-trifluoroethanol (TFE) water mixed solvent, whereas at a higher pH value (5.6) in SDS micelles, DMT1-TM4 exhibited a more stable structure in SDS micelles than that in TFE in terms of changing the pH and temperature. PAGE did not show high-molecular-mass aggregates in SDS micelles. The position of the peptide relative to SDS micelles was probed by the effects of 5- and 16-doxylstearic acids on the intensities of the peptide proton resonances. The results showed that the majority of the peptide is inserted into the hydrophobic interior of SDS micelles, whereas the C-terminal residues are surface-exposed. The ability of DMT1-TM4 to assume transmembrane features may be crucial for its biological function in vivo.
Persistent Identifierhttp://hdl.handle.net/10722/69407
ISSN
2015 Impact Factor: 3.562
2015 SCImago Journal Rankings: 2.582
PubMed Central ID
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLi, Hen_HK
dc.contributor.authorLi, Fen_HK
dc.contributor.authorSun, Hen_HK
dc.contributor.authorQian, ZMen_HK
dc.date.accessioned2010-09-06T06:13:23Z-
dc.date.available2010-09-06T06:13:23Z-
dc.date.issued2003en_HK
dc.identifier.citationBiochemical Journal, 2003, v. 372 n. 3, p. 757-766en_HK
dc.identifier.issn0264-6021en_HK
dc.identifier.urihttp://hdl.handle.net/10722/69407-
dc.description.abstractDivalent-metal transporter 1 (DMT1) is involved in the intestinal iron absorption and in iron transport in the transferrin cycle, It transports metal ions at low pH (≈ 5.5), but not at high pH (7.4), and the transport is a proton-coupled process. Previously it has been shown that transmembrane domain 4 (TM4) is crucial for the function of this protein. Here we provide the first direct experimental evidence for secondary-structural features and membrane insertions of a 24-residue peptide, corresponding to TM4 of DMT1 (DMT1-TM4), in various membrane-mimicking environments by the combined use of CD and NMR spectroscopies. The peptide mainly adopts an α-helical structure in trifluoroethanol, SDS and dodecylphosphocholine micelles, and dimyristoyl phosphatidylcholine and dimyristoyl phosphatidylglycerol small unilamellar vesicles. It has been demonstrated from both Hα secondary shifts and nuclear-Overhauser-enhancement (NOE) connectivities that the peptide is well folded into an a-helix from Val 8 to Lys 23 in SDS micelles at pH 4.0, whereas the N-terminus is highly flexible. The α-helical content estimated from NMR data is in agreement with that extracted from CD simulations. The highest helicity was observed in the anionic phospholipids {1,2-dimyristoyl-sn-glycero-3-[phosphorac-(1-glycerol)]}, indicating that electrostatic attraction is important for peptide binding and insertion into the membranes. The secondary-structural transition of the peptide occurred at pH 4.3 in the 2,2,2-trifluoroethanol (TFE) water mixed solvent, whereas at a higher pH value (5.6) in SDS micelles, DMT1-TM4 exhibited a more stable structure in SDS micelles than that in TFE in terms of changing the pH and temperature. PAGE did not show high-molecular-mass aggregates in SDS micelles. The position of the peptide relative to SDS micelles was probed by the effects of 5- and 16-doxylstearic acids on the intensities of the peptide proton resonances. The results showed that the majority of the peptide is inserted into the hydrophobic interior of SDS micelles, whereas the C-terminal residues are surface-exposed. The ability of DMT1-TM4 to assume transmembrane features may be crucial for its biological function in vivo.en_HK
dc.languageengen_HK
dc.publisherPortland Press Ltd. The Journal's web site is located at http://www.biochemj.orgen_HK
dc.relation.ispartofBiochemical Journalen_HK
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectCircular dichroism (CD)en_HK
dc.subjectDetergenten_HK
dc.subjectDivalent-metal transporter 1 (DMT1)en_HK
dc.subjectNMRen_HK
dc.subjectPhospholipid vesiclesen_HK
dc.subjectSecondary structureen_HK
dc.titleMembrane-inserted conformation of transmembrane domain 4 of divalent-metal transporteren_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0264-6021&volume=372&spage=757&epage=766&date=2003&atitle=Membrane-inserted+conformation+of+transmembrane+domain+4+of+divalent-metal+transporteren_HK
dc.identifier.emailSun, H:hsun@hkucc.hku.hken_HK
dc.identifier.authoritySun, H=rp00777en_HK
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1042/BJ20030075en_HK
dc.identifier.pmid12646040-
dc.identifier.pmcidPMC1223444-
dc.identifier.scopuseid_2-s2.0-0038266898en_HK
dc.identifier.hkuros76948en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0038266898&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume372en_HK
dc.identifier.issue3en_HK
dc.identifier.spage757en_HK
dc.identifier.epage766en_HK
dc.identifier.isiWOS:000183758600010-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLi, H=14023043100en_HK
dc.identifier.scopusauthoridLi, F=36079222200en_HK
dc.identifier.scopusauthoridSun, H=7404827446en_HK
dc.identifier.scopusauthoridQian, ZM=7201384672en_HK
dc.identifier.citeulike3813417-

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