Journal:JBIC:9
From Proteopedia
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| - | <applet load="Jbic91a.pdb" size="600" color="" frame="true" spin="on" Scene ="Journal:JBIC:9/Cv/ | + | <applet load="Jbic91a.pdb" size="600" color="" frame="true" spin="on" Scene ="Journal:JBIC:9/Cv/18" align="right" caption=""/> |
=== Protein and metal cluster structure of the wheat metallothionein domain γ-Ec-1. The second part of the puzzle. === | === Protein and metal cluster structure of the wheat metallothionein domain γ-Ec-1. The second part of the puzzle. === | ||
<big>Jens Loebus, Estevão A. Peroza, Nancy Blüthgen, Thomas Fox, Wolfram Meyer Klaucke, Oliver Zerbe and Eva Freisinger</big><ref>doi</ref> | <big>Jens Loebus, Estevão A. Peroza, Nancy Blüthgen, Thomas Fox, Wolfram Meyer Klaucke, Oliver Zerbe and Eva Freisinger</big><ref>doi</ref> | ||
<hr/> | <hr/> | ||
<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
| - | Ec-1 (Early Cys-labelled protein) from ''Triticum aestivum'' (common bread wheat) belongs to the family of plant metallothioneins. Metallothioneins in general are small (up to approx. 8 kDa) Cys-rich proteins with the ability to coordinate d10 transition metal ions with high thermodynamic affinity. <scene name='Journal:JBIC:9/Cv/9'>Thereby metal-thiolate cluster structures are formed.</scene> The function of these protein is presumably to be found in metal ion homeostasis (Zn(II), Cu(I)), detoxification (Cd(II), Hg(II), etc.), and possibly also in reactive oxygen species scavenging. Wheat Ec-1 consists of 81 amino acids and forms two distinctive domains. The NMR structure of the larger C-terminal β(E)-domain has been already described (PDB ID [[2kak]], <ref name="Peroza">PMID:19361445</ref>) and accommodates four Zn(II) ions. The NMR solution structure of the smaller N-terminal γ-domain shown here consists of the first 24 amino acids of the protein (plus two additional N-terminal vector-derived amino acid residues). The six Cys residues of the γ-domain form a cluster with two Zn(II) or Cd(II) ions similar to the one found in the yeast transcription factor GAL4 (PDB ID [[1aw6]],<ref name="Baleja">PMID:9460244</ref>). The resulting NMR γ-Ec-1 structures containing the metal cluster (Zn(II) or Cd(II)) arrangements <scene name='Journal:JBIC:9/Cv/16'>Cys-9/21</scene> or <scene name='Journal:JBIC:9/Cv/17'>Cys-9/3</scene> were obtained. <scene name='Journal:JBIC:9/Cv/13'>A superposition of the backbone atoms of conformers, in which either Cys-3 or Cys-21 were constrained to be the bridging ligands</scene>, revealed that only small structural adaptations were necessary to transform one form into the other. In the case with Cys-9/21 connectivity <scene name='Journal:JBIC:9/Cv/14'>Cys21</scene> forms bridge between two Zn(II) atoms (in addition to Cys9), whereas in the case with Cys-9/3 arrangement <scene name='Journal:JBIC:9/Cv/15'>Cys3</scene> participate in the bridge formation. Cd(II) isoforms with <scene name='Journal:JBIC:9/Cv1/2'>Cys-9/21</scene> or <scene name='Journal:JBIC:9/Cv1/3'>Cys-9/3</scene> connectivity were similar to the corresponding Zn(II) isoforms. As well as in the case of Zn(II) isoforms, <scene name='Journal:JBIC:9/Cv1/4'>a superposition of the backbone atoms of Cd(II) Cys-9/21 and Cys-9/3 isoforms</scene> revealed that only small structural adaptations were necessary to transform one form into the other. This two-metal ion cluster, as well as the metal ion arrangement found in the larger β(E)-domain, represent new coordination modes that were unprecedented for the superfamily of metallothioneins so far. The functional significance of these findings has to be awaited. | + | Ec-1 (Early Cys-labelled protein) from ''Triticum aestivum'' (common bread wheat) belongs to the family of plant metallothioneins. Metallothioneins in general are small (up to approx. 8 kDa) Cys-rich proteins with the ability to coordinate d10 transition metal ions with high thermodynamic affinity. <scene name='Journal:JBIC:9/Cv/9'>Thereby metal-thiolate cluster structures are formed.</scene> The function of these protein is presumably to be found in metal ion homeostasis (Zn(II), Cu(I)), detoxification (Cd(II), Hg(II), etc.), and possibly also in reactive oxygen species scavenging. Wheat Ec-1 consists of 81 amino acids and forms two distinctive domains. The NMR structure of the larger C-terminal β(E)-domain has been already described (PDB ID [[2kak]], <ref name="Peroza">PMID:19361445</ref>) and accommodates four Zn(II) ions. The NMR solution structure of the smaller N-terminal γ-domain shown here consists of the first 24 amino acids of the protein (plus two additional N-terminal vector-derived amino acid residues). The six Cys residues of the γ-domain form a cluster with two Zn(II) or Cd(II) ions similar to the one found in the yeast transcription factor GAL4 (PDB ID [[1aw6]],<ref name="Baleja">PMID:9460244</ref>). The resulting NMR γ-Ec-1 structures containing the metal cluster (Zn(II) or Cd(II)) arrangements <scene name='Journal:JBIC:9/Cv/16'>Cys-9/21</scene> or <scene name='Journal:JBIC:9/Cv/17'>Cys-9/3</scene> were obtained. <scene name='Journal:JBIC:9/Cv/13'>A superposition of the backbone atoms of conformers, in which either Cys-3 or Cys-21 were constrained to be the bridging ligands</scene>, revealed that only small structural adaptations were necessary to transform one form into the other. In the case with Cys-9/21 connectivity <scene name='Journal:JBIC:9/Cv/14'>Cys21</scene> forms bridge between two Zn(II) atoms (in addition to Cys9), whereas in the case with Cys-9/3 arrangement <scene name='Journal:JBIC:9/Cv/15'>Cys3</scene> participate in the bridge formation. Cd(II) isoforms with <scene name='Journal:JBIC:9/Cv1/2'>Cys-9/21</scene> or <scene name='Journal:JBIC:9/Cv1/3'>Cys-9/3</scene> connectivity were similar to the corresponding Zn(II) isoforms. Alignments of Zn(II)/Cd(II) <scene name='Journal:JBIC:9/Cv1/6'>Cys-9/21</scene> and Zn(II)/Cd(II) <scene name='Journal:JBIC:9/Cv1/5'>Cys-9/3</scene> isoforms highlighted this similarity. As well as in the case of Zn(II) isoforms, <scene name='Journal:JBIC:9/Cv1/4'>a superposition of the backbone atoms of Cd(II) Cys-9/21 and Cys-9/3 isoforms</scene> revealed that only small structural adaptations were necessary to transform one form into the other. This two-metal ion cluster, as well as the metal ion arrangement found in the larger β(E)-domain, represent new coordination modes that were unprecedented for the superfamily of metallothioneins so far. The functional significance of these findings has to be awaited. |
Revision as of 12:03, 17 March 2011
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Protein and metal cluster structure of the wheat metallothionein domain γ-Ec-1. The second part of the puzzle.
Jens Loebus, Estevão A. Peroza, Nancy Blüthgen, Thomas Fox, Wolfram Meyer Klaucke, Oliver Zerbe and Eva Freisinger[1]
Molecular Tour
Ec-1 (Early Cys-labelled protein) from Triticum aestivum (common bread wheat) belongs to the family of plant metallothioneins. Metallothioneins in general are small (up to approx. 8 kDa) Cys-rich proteins with the ability to coordinate d10 transition metal ions with high thermodynamic affinity. The function of these protein is presumably to be found in metal ion homeostasis (Zn(II), Cu(I)), detoxification (Cd(II), Hg(II), etc.), and possibly also in reactive oxygen species scavenging. Wheat Ec-1 consists of 81 amino acids and forms two distinctive domains. The NMR structure of the larger C-terminal β(E)-domain has been already described (PDB ID 2kak, [2]) and accommodates four Zn(II) ions. The NMR solution structure of the smaller N-terminal γ-domain shown here consists of the first 24 amino acids of the protein (plus two additional N-terminal vector-derived amino acid residues). The six Cys residues of the γ-domain form a cluster with two Zn(II) or Cd(II) ions similar to the one found in the yeast transcription factor GAL4 (PDB ID 1aw6,[3]). The resulting NMR γ-Ec-1 structures containing the metal cluster (Zn(II) or Cd(II)) arrangements or were obtained. , revealed that only small structural adaptations were necessary to transform one form into the other. In the case with Cys-9/21 connectivity forms bridge between two Zn(II) atoms (in addition to Cys9), whereas in the case with Cys-9/3 arrangement participate in the bridge formation. Cd(II) isoforms with or connectivity were similar to the corresponding Zn(II) isoforms. Alignments of Zn(II)/Cd(II) and Zn(II)/Cd(II) isoforms highlighted this similarity. As well as in the case of Zn(II) isoforms, revealed that only small structural adaptations were necessary to transform one form into the other. This two-metal ion cluster, as well as the metal ion arrangement found in the larger β(E)-domain, represent new coordination modes that were unprecedented for the superfamily of metallothioneins so far. The functional significance of these findings has to be awaited.
- ↑ doi
- ↑ Peroza EA, Schmucki R, Guntert P, Freisinger E, Zerbe O. The beta(E)-domain of wheat E(c)-1 metallothionein: a metal-binding domain with a distinctive structure. J Mol Biol. 2009 Mar 20;387(1):207-18. Epub 2009 Jan 27. PMID:19361445 doi:10.1016/j.jmb.2009.01.035
- ↑ Baleja JD, Thanabal V, Wagner G. Refined solution structure of the DNA-binding domain of GAL4 and use of 3J(113Cd,1H) in structure determination. J Biomol NMR. 1997 Dec;10(4):397-401. PMID:9460244
