Journal:JBIC:9
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| - | < | + | <StructureSection load='Jbic91a.pdb' size='450' side='right' scene='Journal:JBIC:9/Cv/18' 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> | + | <big>Jens Loebus, Estevão A. Peroza, Nancy Blüthgen, Thomas Fox, Wolfram Meyer Klaucke, Oliver Zerbe and Eva Freisinger</big><ref>DOI 10.1007/s00775-011-0770-2</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 arrangements <scene name='Journal:JBIC:9/Cv/ | + | 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 <scene name='Journal:JBIC:9/Cv2/2'>only small structural adaptations were necessary to transform one form into the other</scene>. 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 <scene name='Journal:JBIC:9/Cv1/6'>Zn(II)/Cd(II) Cys-9/21</scene> and <scene name='Journal:JBIC:9/Cv1/5'>Zn(II)/Cd(II) Cys-9/3</scene> isoforms highlighted <scene name='Journal:JBIC:9/Cv2/4'>this similarity (Zn(II)/Cd(II) Cys-9/21 alignment is shown as example)</scene>. 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 <scene name='Journal:JBIC:9/Cv2/3'>only small structural adaptations were necessary to transform one form into the other</scene>. 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. |
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| + | '''PDB references:''' [[2l61]], [[2l62]] | ||
| + | </StructureSection> | ||
<references/> | <references/> | ||
__NOEDITSECTION__ | __NOEDITSECTION__ | ||
Current revision
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- ↑ Loebus J, Peroza EA, Bluthgen N, Fox T, Meyer-Klaucke W, Zerbe O, Freisinger E. Protein and metal cluster structure of the wheat metallothionein domain gamma-E(c)-1: the second part of the puzzle. J Biol Inorg Chem. 2011 Mar 25. PMID:21437709 doi:10.1007/s00775-011-0770-2
- ↑ 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
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