Journal:JBIC:6
From Proteopedia
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Sco is a family of proteins ubiquitous to all kingdoms of life. Ortholog and paralog genome browsing has shown that more than one representative of this class are often present in bacterial and eukaryotic genomes. They have a thioredoxin-like fold and bind a single Cu(I) or Cu(II) ion through a <scene name='Journal:JBIC:6/Cxxc_motif/2'>CXXXC motif</scene> and a <scene name='Journal:JBIC:6/Cxxc_motif_his/1'>conserved His ligand</scene>, with both tight and weak affinities. They have been implicated in the assembly of the CuA site of cytochrome c oxidase as copper chaperones and/or thioredoxins. Starting from our previous bioinformatic analysis of Sco proteins encoded in prokaryotic genomes we focused on the genome of ''Pseudomonas putida'' KT2440, which contains six Sco like sequences in different genomic contexts. The protein named pp3183 has been chosen as a target since it is formed by a Sco domain fused to a well-known electron transfer protein, cyt c, this system being potentially involved in electron transfer processes. The solution structures of both <scene name='Journal:JBIC:6/Opening/7'>Sco domains</scene> and <scene name='Journal:JBIC:6/Cyt_c_openin/1'>cyt c</scene>, separately expressed, were determined and their copper binding/electron transfer properties were investigated. | Sco is a family of proteins ubiquitous to all kingdoms of life. Ortholog and paralog genome browsing has shown that more than one representative of this class are often present in bacterial and eukaryotic genomes. They have a thioredoxin-like fold and bind a single Cu(I) or Cu(II) ion through a <scene name='Journal:JBIC:6/Cxxc_motif/2'>CXXXC motif</scene> and a <scene name='Journal:JBIC:6/Cxxc_motif_his/1'>conserved His ligand</scene>, with both tight and weak affinities. They have been implicated in the assembly of the CuA site of cytochrome c oxidase as copper chaperones and/or thioredoxins. Starting from our previous bioinformatic analysis of Sco proteins encoded in prokaryotic genomes we focused on the genome of ''Pseudomonas putida'' KT2440, which contains six Sco like sequences in different genomic contexts. The protein named pp3183 has been chosen as a target since it is formed by a Sco domain fused to a well-known electron transfer protein, cyt c, this system being potentially involved in electron transfer processes. The solution structures of both <scene name='Journal:JBIC:6/Opening/7'>Sco domains</scene> and <scene name='Journal:JBIC:6/Cyt_c_openin/1'>cyt c</scene>, separately expressed, were determined and their copper binding/electron transfer properties were investigated. | ||
| - | The thioredoxin-like Sco domain of pp3183 does not bind copper(II), binds copper(I) with weak affinity without involving the conserved His, and has redox properties consisting of thioredoxin activity and the ability of reducing copper(II) to copper(I), and <scene name='Journal:JBIC:6/Cyt_c_opening_ron/1'>iron(III) to iron(II) in the cyt c domain</scene>. These findings indicate that the His ligand coordination is the discriminating factor for introducing a metallochaperone function in a thioredoxin-like fold, typically responsible of electron transfer processes. A comparative structural analysis of the Sco domain from ''P. putida'' vs. eukaryotic Sco proteins revealed structural determinants affecting the formation of a tight vs. weak affinity copper binding site in Sco proteins. <scene name='Journal:JBIC:6/Cu_eukaryotic_sco/2'> | + | The thioredoxin-like Sco domain of pp3183 does not bind copper(II), binds copper(I) with weak affinity without involving the conserved His, and has redox properties consisting of thioredoxin activity and the ability of reducing copper(II) to copper(I), and <scene name='Journal:JBIC:6/Cyt_c_opening_ron/1'>iron(III) to iron(II) in the cyt c domain</scene>. These findings indicate that the His ligand coordination is the discriminating factor for introducing a metallochaperone function in a thioredoxin-like fold, typically responsible of electron transfer processes. A comparative structural analysis of the Sco domain from ''P. putida'' vs. eukaryotic Sco proteins revealed structural determinants affecting the formation of a tight vs. weak affinity copper binding site in Sco proteins. In ppSco proteins, the CXXXC motif and His-ligand are surrounded by neighboring polar residues. Eukaryotic <scene name='Journal:JBIC:6/Cu_eukaryotic_sco/2'>Sco proteins</scene> possess the same <scene name='Journal:JBIC:6/Cu_eukaryotic_cxxxc/3'>conserved CXXXC motif</scene> and neighboring <scene name='Journal:JBIC:6/Cu_eukaryotic_cxxxc_his/2'>copper binding His residue</scene> as is found in ''P. putida'' Sco proteins. <scene name='Journal:JBIC:6/Cu_eukaryotic_cxxxc_hydro/1'>Hydrophobic interactions</scene> between the CXXXC region and the conserved His region <scene name='Journal:JBIC:6/Cu_eukaryotic_cxxxc_hydro_in/1'>freeze the copper binding state</scene> conformation only in eukaryotic Scos determining a tight affinity binding site. |
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Revision as of 07:12, 1 December 2010
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Sco Proteins are Involved in Electron Transfer Processes
I. Bertini & L. Banci [1]
Molecular Tour
Sco is a family of proteins ubiquitous to all kingdoms of life. Ortholog and paralog genome browsing has shown that more than one representative of this class are often present in bacterial and eukaryotic genomes. They have a thioredoxin-like fold and bind a single Cu(I) or Cu(II) ion through a and a , with both tight and weak affinities. They have been implicated in the assembly of the CuA site of cytochrome c oxidase as copper chaperones and/or thioredoxins. Starting from our previous bioinformatic analysis of Sco proteins encoded in prokaryotic genomes we focused on the genome of Pseudomonas putida KT2440, which contains six Sco like sequences in different genomic contexts. The protein named pp3183 has been chosen as a target since it is formed by a Sco domain fused to a well-known electron transfer protein, cyt c, this system being potentially involved in electron transfer processes. The solution structures of both and , separately expressed, were determined and their copper binding/electron transfer properties were investigated.
The thioredoxin-like Sco domain of pp3183 does not bind copper(II), binds copper(I) with weak affinity without involving the conserved His, and has redox properties consisting of thioredoxin activity and the ability of reducing copper(II) to copper(I), and . These findings indicate that the His ligand coordination is the discriminating factor for introducing a metallochaperone function in a thioredoxin-like fold, typically responsible of electron transfer processes. A comparative structural analysis of the Sco domain from P. putida vs. eukaryotic Sco proteins revealed structural determinants affecting the formation of a tight vs. weak affinity copper binding site in Sco proteins. In ppSco proteins, the CXXXC motif and His-ligand are surrounded by neighboring polar residues. Eukaryotic possess the same and neighboring as is found in P. putida Sco proteins. between the CXXXC region and the conserved His region conformation only in eukaryotic Scos determining a tight affinity binding site.
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