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Structural and func...
Structural and functional analysis of SoPIP2;1 mutants adds insight into plant aquaporin gating.
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- Nyblom, Anna Maria, 1975 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Frick, Anna, 1982 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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- Wang, Yi (author)
- University of Illinois
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- Ekvall, Mikael, 1977 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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- Hallgren, Karin (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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- Hedfalk, Kristina, 1969 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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- Neutze, Richard, 1969 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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- Tajkhorshid, Emad (author)
- University of Illinois
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- Törnroth-Horsefield, Susanna, 1973 (author)
- Gothenburg University,Göteborgs universitet,Institutionen för kemi,Department of Chemistry
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(creator_code:org_t)
- Elsevier BV, 2009
- 2009
- English.
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In: Journal of molecular biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 387:3, s. 653-68
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http://dx.doi.org/10...
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Abstract
Subject headings
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- Plant plasma membrane aquaporins facilitate water flux into and out of plant cells, thus coupling their cellular function to basic aspects of plant physiology. Posttranslational modifications of conserved phosphorylation sites, changes in cytoplasmic pH and the binding of Ca(2+) can regulate water transport activity by gating the plasma membrane aquaporins. A structural mechanism unifying these diverse biochemical signals has emerged for the spinach aquaporin SoPIP2;1, although several questions concerning the opening mechanism remain. Here, we describe the X-ray structures of the S115E and S274E single SoPIP2;1 mutants and the corresponding double mutant. Phosphorylation of these serines is believed to increase water transport activity of SoPIP2;1 by opening the channel. However, all mutants crystallised in a closed conformation, as confirmed by water transport assays, implying that neither substitution fully mimics the phosphorylated state. Nevertheless, a half-turn extension of transmembrane helix 1 occurs upon the substitution of Ser115, which draws the C(alpha) atom of Glu31 10 A away from its wild-type conformation, thereby disrupting the divalent cation binding site involved in the gating mechanism. Mutation of Ser274 disorders the C-terminus but no other significant conformational changes are observed. Inspection of the hydrogen-bond interactions within loop D suggested that the phosphorylation of Ser188 may also produce an open channel, and this was supported by an increased water transport activity for the S188E mutant and molecular dynamics simulations. These findings add additional insight into the general mechanism of plant aquaporin gating.
Subject headings
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
Keyword
- phoshorylation
- X-ray crystallography
- membrane protein
- gating
- plant aquaporin
- X-ray crystallography; membrane protein; plant aquaporin; gating; phoshorylation
Publication and Content Type
- art (subject category)
- ref (subject category)
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- By the author/editor
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Nyblom, Anna Mar ...
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Frick, Anna, 198 ...
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Wang, Yi
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Ekvall, Mikael, ...
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Hallgren, Karin
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Hedfalk, Kristin ...
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show more...
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Neutze, Richard, ...
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Tajkhorshid, Ema ...
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Törnroth-Horsefi ...
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- About the subject
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Chemical Science ...
- Articles in the publication
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Journal of molec ...
- By the university
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Chalmers University of Technology
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University of Gothenburg