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  • 1
    Publication Date: 2010-10-12
    Description: CLC proteins transport chloride (Cl(-)) ions across cell membranes to control the electrical potential of muscle cells, transfer electrolytes across epithelia, and control the pH and electrolyte composition of intracellular organelles. Some members of this protein family are Cl(-) ion channels, whereas others are secondary active transporters that exchange Cl(-) ions and protons (H(+)) with a 2:1 stoichiometry. We have determined the structure of a eukaryotic CLC transporter at 3.5 angstrom resolution. Cytoplasmic cystathionine beta-synthase (CBS) domains are strategically positioned to regulate the ion-transport pathway, and many disease-causing mutations in human CLCs reside on the CBS-transmembrane interface. Comparison with prokaryotic CLC shows that a gating glutamate residue changes conformation and suggests a basis for 2:1 Cl(-)/H(+) exchange and a simple mechanistic connection between CLC channels and transporters.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3079386/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3079386/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Feng, Liang -- Campbell, Ernest B -- Hsiung, Yichun -- MacKinnon, Roderick -- P30 EB009998/EB/NIBIB NIH HHS/ -- R01 GM043949/GM/NIGMS NIH HHS/ -- R01 GM043949-20/GM/NIGMS NIH HHS/ -- R01 GM043949-21/GM/NIGMS NIH HHS/ -- Howard Hughes Medical Institute/ -- New York, N.Y. -- Science. 2010 Oct 29;330(6004):635-41. doi: 10.1126/science.1195230. Epub 2010 Sep 30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Neurobiology and Biophysics, Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20929736" target="_blank"〉PubMed〈/a〉
    Keywords: Algal Proteins/chemistry/metabolism ; Animals ; Antiporters/*chemistry/metabolism ; Binding Sites ; Cell Line ; Cell Membrane/chemistry ; Chloride Channels/*chemistry/metabolism ; Chlorides/*metabolism ; Crystallization ; Crystallography, X-Ray ; Cystathionine beta-Synthase/chemistry ; Cytoplasm/chemistry ; Glutamic Acid/metabolism ; Ion Channel Gating ; Ion Transport ; Models, Biological ; Models, Molecular ; Protein Conformation ; Protein Multimerization ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Protein Subunits/chemistry ; Protons ; Rhodophyta/*chemistry/metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-09-05
    Description: SWEETs and their prokaryotic homologues are monosaccharide and disaccharide transporters that are present from Archaea to plants and humans. SWEETs play crucial roles in cellular sugar efflux processes: that is, in phloem loading, pollen nutrition and nectar secretion. Their bacterial homologues, which are called SemiSWEETs, are among the smallest known transporters. Here we show that SemiSWEET molecules, which consist of a triple-helix bundle, form symmetrical, parallel dimers, thereby generating the translocation pathway. Two SemiSWEET isoforms were crystallized, one in an apparently open state and one in an occluded state, indicating that SemiSWEETs and SWEETs are transporters that undergo rocking-type movements during the transport cycle. The topology of the triple-helix bundle is similar yet distinct to that of the basic building block of animal and plant major facilitator superfamily (MFS) transporters (for example, GLUTs and SUTs). This finding indicates two possibilities: that SWEETs and MFS transporters evolved from an ancestral triple-helix bundle or that the triple-helix bundle represents convergent evolution. In SemiSWEETs and SWEETs, two triple-helix bundles are arranged in a parallel configuration to produce the 6- and 6 + 1-transmembrane-helix pores, respectively. In the 12-transmembrane-helix MFS transporters, four triple-helix bundles are arranged into an alternating antiparallel configuration, resulting in a much larger 2 x 2 triple-helix bundle forming the pore. Given the similarity of SemiSWEETs and SWEETs to PQ-loop amino acid transporters and to mitochondrial pyruvate carriers (MPCs), the structures characterized here may also be relevant to other transporters in the MtN3 clan. The insight gained from the structures of these transporters and from the analysis of mutations of conserved residues will improve the understanding of the transport mechanism, as well as allow comparative studies of the different superfamilies involved in sugar transport and the evolution of transporters in general.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300204/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300204/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xu, Yan -- Tao, Yuyong -- Cheung, Lily S -- Fan, Chao -- Chen, Li-Qing -- Xu, Sophia -- Perry, Kay -- Frommer, Wolf B -- Feng, Liang -- P41 GM103403/GM/NIGMS NIH HHS/ -- England -- Nature. 2014 Nov 20;515(7527):448-52. doi: 10.1038/nature13670. Epub 2014 Sep 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉1] Department of Molecular and Cellular Physiology, 279 Campus Drive, Stanford University School of Medicine, Stanford, California 94305, USA [2]. ; 1] Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA [2]. ; Department of Molecular and Cellular Physiology, 279 Campus Drive, Stanford University School of Medicine, Stanford, California 94305, USA. ; Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA. ; Department of Biology, Stanford University, Stanford, California 94305, USA. ; NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Building 436E, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA. ; 1] Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA [2] Department of Biology, Stanford University, Stanford, California 94305, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25186729" target="_blank"〉PubMed〈/a〉
    Keywords: Arabidopsis/chemistry ; Bacterial Proteins/*chemistry/metabolism ; Crystallography, X-Ray ; Evolution, Molecular ; Glucose/metabolism ; Leptospira/*chemistry/genetics ; Models, Molecular ; Monosaccharide Transport Proteins/*chemistry/genetics/metabolism ; Movement ; Protein Conformation ; Protein Multimerization ; Structure-Activity Relationship ; Vibrio/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2007-12-08
    Description: Regulated intramembrane proteolysis by members of the site-2 protease (S2P) family is an important signaling mechanism conserved from bacteria to humans. Here we report the crystal structure of the transmembrane core domain of an S2P metalloprotease from Methanocaldococcus jannaschii. The protease consists of six transmembrane segments, with the catalytic zinc atom coordinated by two histidine residues and one aspartate residue approximately 14 angstroms into the lipid membrane surface. The protease exhibits two distinct conformations in the crystals. In the closed conformation, the active site is surrounded by transmembrane helices and is impermeable to substrate peptide; water molecules gain access to zinc through a polar, central channel that opens to the cytosolic side. In the open conformation, transmembrane helices alpha1 and alpha6 separate from each other by 10 to 12 angstroms, exposing the active site to substrate entry. The structure reveals how zinc embedded in an integral membrane protein can catalyze peptide cleavage.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Feng, Liang -- Yan, Hanchi -- Wu, Zhuoru -- Yan, Nieng -- Wang, Zhe -- Jeffrey, Philip D -- Shi, Yigong -- New York, N.Y. -- Science. 2007 Dec 7;318(5856):1608-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18063795" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Archaeal Proteins/chemistry/metabolism ; Bacterial Proteins/*chemistry/metabolism ; Binding Sites ; Catalysis ; Catalytic Domain ; Crystallization ; Crystallography, X-Ray ; Dimerization ; Membrane Proteins/*chemistry/metabolism ; Metalloendopeptidases/*chemistry/metabolism ; Methanococcus/*enzymology ; Molecular Sequence Data ; Protein Conformation ; Protein Structure, Secondary ; Protein Structure, Tertiary ; Water ; Zinc/chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2015-10-20
    Description: Eukaryotes rely on efficient distribution of energy and carbon skeletons between organs in the form of sugars. Glucose in animals and sucrose in plants serve as the dominant distribution forms. Cellular sugar uptake and release require vesicular and/or plasma membrane transport proteins. Humans and plants use proteins from three superfamilies for sugar translocation: the major facilitator superfamily (MFS), the sodium solute symporter family (SSF; only in the animal kingdom), and SWEETs. SWEETs carry mono- and disaccharides across vacuolar or plasma membranes. Plant SWEETs play key roles in sugar translocation between compartments, cells, and organs, notably in nectar secretion, phloem loading for long distance translocation, pollen nutrition, and seed filling. Plant SWEETs cause pathogen susceptibility possibly by sugar leakage from infected cells. The vacuolar Arabidopsis thaliana AtSWEET2 sequesters sugars in root vacuoles; loss-of-function mutants show increased susceptibility to Pythium infection. Here we show that its orthologue, the vacuolar glucose transporter OsSWEET2b from rice (Oryza sativa), consists of an asymmetrical pair of triple-helix bundles, connected by an inversion linker transmembrane helix (TM4) to create the translocation pathway. Structural and biochemical analyses show OsSWEET2b in an apparent inward (cytosolic) open state forming homomeric trimers. TM4 tightly interacts with the first triple-helix bundle within a protomer and mediates key contacts among protomers. Structure-guided mutagenesis of the close paralogue SWEET1 from Arabidopsis identified key residues in substrate translocation and protomer crosstalk. Insights into the structure-function relationship of SWEETs are valuable for understanding the transport mechanism of eukaryotic SWEETs and may be useful for engineering sugar flux.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734654/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734654/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tao, Yuyong -- Cheung, Lily S -- Li, Shuo -- Eom, Joon-Seob -- Chen, Li-Qing -- Xu, Yan -- Perry, Kay -- Frommer, Wolf B -- Feng, Liang -- P41 GM103403/GM/NIGMS NIH HHS/ -- England -- Nature. 2015 Nov 12;527(7577):259-63. doi: 10.1038/nature15391. Epub 2015 Oct 19.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cellular Physiology, 279 Campus Drive, Stanford University School of Medicine, Stanford, California 94305, USA. ; Carnegie Institution for Science, Department of Plant Biology, 260 Panama Street, Stanford, California 94305, USA. ; Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610014, China. ; NE-CAT and Dep. of Chemistry and Chemical Biology, Cornell University, Building 436E, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26479032" target="_blank"〉PubMed〈/a〉
    Keywords: Arabidopsis/chemistry ; Arabidopsis Proteins/chemistry/genetics/metabolism ; Biological Transport ; Crystallography, X-Ray ; Glucose Transport Proteins, Facilitative/*chemistry/genetics/metabolism ; HEK293 Cells ; Humans ; Models, Molecular ; Monosaccharide Transport Proteins/chemistry/genetics/metabolism ; Oryza/*chemistry/genetics ; Phloem ; Plant Proteins/*chemistry/metabolism ; *Protein Multimerization ; Protein Structure, Quaternary ; Protein Structure, Secondary ; Structure-Activity Relationship
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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