Structural clues in the sequences of the aquaporins

Heymann, J. Bernard; Engel, Andréas

doi:10.1006/jmbi.1999.3413

Cited by 136 publications

(128 citation statements)

References 65 publications

(89 reference statements)

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“…The crucial role of Phe24 for the speci¢city of AQP1 is further con¢rmed by sequence analyses of the aquaporin family [15,33]. Together with Leu149, it forms a hydrophobic pair in AQP1.…”

Section: Discussionmentioning

confidence: 93%

A refined structure of human aquaporin‐1

2001

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A refined structure of the human water channel aquaporin-1 is presented. The model rests on the high resolution X-ray structure of the homologous bacterial glycerol transporter GlpF, electron crystallographic data at 3.8 A î resolution and a multiple sequence alignment of the aquaporin superfamily. The crystallographic R and free R values (36.7% and 37.8%) for the refined structure are significantly lower than for previous models. Improved geometry and enhanced stability in molecular dynamics simulations demonstrate a significant improvement of the aquaporin-1 structure. Comparison with previous aquaporin-1 models shows significant differences, not only in the loop regions, but also in the core of the water channel. ß

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“…The crucial role of Phe24 for the speci¢city of AQP1 is further con¢rmed by sequence analyses of the aquaporin family [15,33]. Together with Leu149, it forms a hydrophobic pair in AQP1.…”

Section: Discussionmentioning

confidence: 93%

A refined structure of human aquaporin‐1

2001

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“…27). When expressed in Xenopus laevis oocytes, GlpF was shown to exhibit high levels of glycerol transport but negligible water transport (11).…”

Section: Discussionmentioning

confidence: 99%

Reconstitution and functional comparison of purified GlpF and AqpZ, the glycerol and water channels from Escherichia coli

Borgnia

Agre

2001

Proc. Natl. Acad. Sci. U.S.A.

195

192

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A large family of membrane channel proteins selective for transport of water (aquaporins) or water plus glycerol (aquaglyceroporins) has been found in diverse life forms. Escherichia coli has two members of this family-a water channel, AqpZ, and a glycerol facilitator, GlpF. Despite having similar primary amino acid sequences and predicted structures, the oligomeric state and solute selectivity of AqpZ and GlpF are disputed. Here we report biochemical and functional characterizations of affinity-purified GlpF and compare it to AqpZ. Histidine-tagged (His-GlpF) and hemagglutinin-tagged (HA-GlpF) polypeptides encoded by a bicistronic construct were expressed in bacteria. HA-GlpF and His-GlpF appear to form oligomers during Ni-nitrilotriacetate affinity purification. Sucrose gradient sedimentation analyses showed that the oligomeric state of octyl glucoside-solubilized GlpF varies: low ionic strength favors subunit dissociation, whereas Mg 2؉ stabilizes tetrameric assembly. Reconstitution of affinity-purified GlpF into proteoliposomes increases glycerol permeability more than 100-fold and water permeability up to 10-fold compared with control liposomes. Glycerol and water permeability of GlpF both occur with low Arrhenius activation energies and are reversibly inhibited by HgCl2. Our studies demonstrate that, unlike AqpZ, a waterselective stable tetramer, purified GlpF exists in multiple oligomeric forms under nondenaturing conditions and is highly permeable to glycerol but less well permeated by water.

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“…The structures of aquaporins have been intensively studied, revealing the functions of their conserved motifs and post-translational modification sites, in water transport [3][4][5][6][7][8][9][10][11][12][13][14][15]. The expression patterns of aquaporin genes in response to salt, drought, cold, submergence, light, and phytohormones have also been characterized in various plants [16][17][18][19][20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Expression and functional analysis of the rice plasma-membrane intrinsic protein gene family

et al. 2006

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Plasma membrane intrinsic proteins (PIPs) are a subfamily of aquaporins that enable fast and controlled translocation of water across the membrane. In this study, we systematically identified and cloned ten PIP genes from rice. Based on the similarity of the amino acid sequences they encoded, these rice PIP genes were classified into two groups and designated as OsPIP1-1 to OsPIP1-3 and OsPIP2-1 to OsPIP2-7 following the nomenclature of PIP genes in maize. Quantitative RT-PCR analysis identified three root-specific and one leaf-specific OsPIP genes. Furthermore, the expression profile of each OsPIP gene in response to salt, drought and ABA treatment was examined in detail. Analysis on transgenic plants over-expressing of either OsPIP1 (OsPIP1-1) or OsPIP2 (OsPIP2-2) in wild-type Arabidopsis, showed enhanced tolerance to salt (100 mM of NaCl) and drought (200 mM of mannitol), but not to salt treatment of higher concentration (150 mM of NaCl). Taken together, these data suggest a distinct role of each OsPIP gene in response to different stresses, and should add a new layer to the understanding of the physiological function of rice PIP genes.

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Structural clues in the sequences of the aquaporins

Cited by 136 publications

References 65 publications

A refined structure of human aquaporin‐1

A refined structure of human aquaporin‐1

Reconstitution and functional comparison of purified GlpF and AqpZ, the glycerol and water channels from Escherichia coli

Expression and functional analysis of the rice plasma-membrane intrinsic protein gene family

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