Journal:FEBS Open Bio:2
From Proteopedia
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<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
| - | Glutathione transferases ('''GSTs''') are involved in many processes in plant biochemistry, with their best characterised role being the detoxification of xenobiotics through their conjugation with glutathione. GSTs have also been implicated in noncatalytic roles, including the binding and transport of small heterocyclic ligands such as indole hormones, phytoalexins and flavonoids. Although evidence for ligand binding and transport has been obtained using gene deletions and ligand binding studies on purified GSTs, there has been no structural evidence for the binding of relevant ligands in noncatalytic sites. Here we provide evidence of noncatalytic ligand-binding sites in the phi class GST from the model plant ''Arabidopsis thaliana'', ''At''GSTF2, revealed by X-ray crystallography. Ligands used in this study: 1 = <scene name='76/763766/Cv/10'>Indole-3-aldehyde</scene>; 2 = <scene name='76/763766/Cv/11'>Camalexin</scene>; 3 = <scene name='76/763766/Cv/12'>Quercetrin</scene>; 4 = <scene name='76/763766/Cv/13'>Quercetin</scene>. Complexes of the ''At''GSTF2 dimer were obtained with indole-3-aldehyde, camalexin, the flavonoid quercetrin and its non-rhamnosylated analogue quercetin, at resolutions of 2.00, 2.77, 2.25 and 2.38 Å respectively. Two symmetry-equivalent-binding sites ('''L1''') were identified at the periphery of the dimer, and one more ('''L2''') at the dimer interface. <scene name='76/763766/Cv/15'>Structure of AtGSTF2 dimer</scene>. The figure is derived using the complex with indole-3-aldehyde and shows selected helices and location of ligand-binding sites '''L1''' and '''L2''' labelled for ease of reference. In the complexes, indole-3-aldehyde and quercetrin were found at both '''L1''' and '''L2''' sites, but camalexin was found only at the '''L1''' sites and quercetin only at the '''L2''' site. | + | Glutathione transferases ('''GSTs''') are involved in many processes in plant biochemistry, with their best characterised role being the detoxification of xenobiotics through their conjugation with glutathione. GSTs have also been implicated in noncatalytic roles, including the binding and transport of small heterocyclic ligands such as indole hormones, phytoalexins and flavonoids. Although evidence for ligand binding and transport has been obtained using gene deletions and ligand binding studies on purified GSTs, there has been no structural evidence for the binding of relevant ligands in noncatalytic sites. Here we provide evidence of noncatalytic ligand-binding sites in the phi class GST from the model plant ''Arabidopsis thaliana'', ''At''GSTF2, revealed by X-ray crystallography. Ligands used in this study: 1 = <scene name='76/763766/Cv/10'>Indole-3-aldehyde</scene>; 2 = <scene name='76/763766/Cv/11'>Camalexin</scene>; 3 = <scene name='76/763766/Cv/12'>Quercetrin</scene>; 4 = <scene name='76/763766/Cv/13'>Quercetin</scene>. Complexes of the ''At''GSTF2 dimer were obtained with indole-3-aldehyde, camalexin, the flavonoid quercetrin and its non-rhamnosylated analogue quercetin, at resolutions of 2.00, 2.77, 2.25 and 2.38 Å respectively. Two symmetry-equivalent-binding sites ('''L1''') were identified at the periphery of the dimer, and one more ('''L2''') at the dimer interface. <scene name='76/763766/Cv/15'>Structure of AtGSTF2 dimer</scene>. The figure is derived using the complex with indole-3-aldehyde and shows selected helices and location of ligand-binding sites '''L1''' and '''L2''' labelled for ease of reference. In the complexes, indole-3-aldehyde and quercetrin were found at both '''L1''' and '''L2''' sites, but camalexin was found only at the '''L1''' sites and quercetin only at the '''L2''' site. Structure of dimers ‘A/B’ from ligand complex structures of ''At''GSTF2 and showing location of ligands in binding sites '''L1''' and '''L2''': |
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| - | Structure of dimers ‘A/B’ from ligand complex structures of ''At''GSTF2 and showing location of ligands in binding sites '''L1''' and '''L2''': | + | |
*'''I''' <scene name='76/763766/Cv/17'>Complex with Indole-3-aldehyde 1</scene>; | *'''I''' <scene name='76/763766/Cv/17'>Complex with Indole-3-aldehyde 1</scene>; | ||
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*'''IV''' Complex with Quercetin 4; | *'''IV''' Complex with Quercetin 4; | ||
*'''V''' 1GNW, an AtGSTF2 complex with two molecules of S-hexyl glutathione ‘GSX’, showing the GSH conjugation site. | *'''V''' 1GNW, an AtGSTF2 complex with two molecules of S-hexyl glutathione ‘GSX’, showing the GSH conjugation site. | ||
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| + | Ligand binding at each site appeared to be largely determined through hydrophobic interactions. The crystallographic studies support previous conclusions made on ligand binding in noncatalytic sites by ''At''GSTF2 based on isothermal calorimetry experiments (Dixon ''et al''. (2011)<ref>pmid 21631432 </ref>) and suggest a mode of ligand binding in GSTs commensurate with a possible role in ligand transport. | ||
</StructureSection> | </StructureSection> | ||
<references/> | <references/> | ||
__NOEDITSECTION__ | __NOEDITSECTION__ | ||
Revision as of 12:26, 24 September 2017
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- ↑ Ahmad L, Rylott EL, Bruce NC, Edwards R, Grogan G. Structural evidence for Arabidopsis glutathione transferase AtGSTF2 functioning as a transporter of small organic ligands. FEBS Open Bio. 2016 Dec 22;7(2):122-132. doi: 10.1002/2211-5463.12168., eCollection 2017 Feb. PMID:28174680 doi:http://dx.doi.org/10.1002/2211-5463.12168
- ↑ Dixon DP, Sellars JD, Edwards R. The Arabidopsis phi class glutathione transferase AtGSTF2: binding and regulation by biologically active heterocyclic ligands. Biochem J. 2011 Aug 15;438(1):63-70. doi: 10.1042/BJ20101884. PMID:21631432 doi:http://dx.doi.org/10.1042/BJ20101884
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