1pq4: Difference between revisions
New page: left|200px<br /><applet load="1pq4" size="450" color="white" frame="true" align="right" spinBox="true" caption="1pq4, resolution 1.90Å" /> '''Crystal structure of... |
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[[Image:1pq4.jpg|left|200px]]<br /><applet load="1pq4" size=" | [[Image:1pq4.jpg|left|200px]]<br /><applet load="1pq4" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1pq4, resolution 1.90Å" /> | caption="1pq4, resolution 1.90Å" /> | ||
'''Crystal structure of ZnuA'''<br /> | '''Crystal structure of ZnuA'''<br /> | ||
==Overview== | ==Overview== | ||
A number of bacterial metal transporters belong to the cluster 9 family of | A number of bacterial metal transporters belong to the cluster 9 family of ABC transporters. The residues in the periplasmic domain thought to be involved in metal binding seem highly conserved and yet the transporters have varying metal specificity. To solve this seeming paradox and ascertain how metal specificity is exacted, the structure of ZnuA, the periplasmic domain of a zinc transporter from Synechocystis 6803, has been determined to a resolution of 1.9A. In previously determined structures of homologous proteins, four residues chelate the bound metal. From sequence alignments of the cluster 9 metal transporters, the fourth residue in this metal-binding site, an aspartate, is also present in the appropriate position in the ZnuA sequence. However, this result is misleading, since our structural data indicate that zinc binds via only three histidine residues and the aspartate is replaced by a large hydrophobic cavity. We propose that ZnuA binds zinc over manganese by providing only three ligating residues. ZnuA has a highly charged and mobile loop that protrudes from the protein in the vicinity of the metal-binding site. Similar loops are found in other types of zinc transporters but not manganese transporters. Therefore, we propose that the function of this domain is to act as a zinc chaperone to facilitate acquisition. Therefore, while Mn2+ transporters can bind Zn2+ in vitro they may not be able to acquire it in vivo without this structure because of the low concentration of free Zn2+. | ||
==About this Structure== | ==About this Structure== | ||
1PQ4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | 1PQ4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Synechocystis_sp. Synechocystis sp.] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PQ4 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Banerjee, S.]] | [[Category: Banerjee, S.]] | ||
[[Category: Bhattacharyya-Pakrasi, M.]] | [[Category: Bhattacharyya-Pakrasi, M.]] | ||
[[Category: Pakrasi, H | [[Category: Pakrasi, H B.]] | ||
[[Category: Smith, T | [[Category: Smith, T J.]] | ||
[[Category: Wei, B.]] | [[Category: Wei, B.]] | ||
[[Category: ZN]] | [[Category: ZN]] | ||
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[[Category: znua]] | [[Category: znua]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:31:22 2008'' | ||
Revision as of 15:31, 21 February 2008
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Crystal structure of ZnuA
OverviewOverview
A number of bacterial metal transporters belong to the cluster 9 family of ABC transporters. The residues in the periplasmic domain thought to be involved in metal binding seem highly conserved and yet the transporters have varying metal specificity. To solve this seeming paradox and ascertain how metal specificity is exacted, the structure of ZnuA, the periplasmic domain of a zinc transporter from Synechocystis 6803, has been determined to a resolution of 1.9A. In previously determined structures of homologous proteins, four residues chelate the bound metal. From sequence alignments of the cluster 9 metal transporters, the fourth residue in this metal-binding site, an aspartate, is also present in the appropriate position in the ZnuA sequence. However, this result is misleading, since our structural data indicate that zinc binds via only three histidine residues and the aspartate is replaced by a large hydrophobic cavity. We propose that ZnuA binds zinc over manganese by providing only three ligating residues. ZnuA has a highly charged and mobile loop that protrudes from the protein in the vicinity of the metal-binding site. Similar loops are found in other types of zinc transporters but not manganese transporters. Therefore, we propose that the function of this domain is to act as a zinc chaperone to facilitate acquisition. Therefore, while Mn2+ transporters can bind Zn2+ in vitro they may not be able to acquire it in vivo without this structure because of the low concentration of free Zn2+.
About this StructureAbout this Structure
1PQ4 is a Single protein structure of sequence from Synechocystis sp. with as ligand. Full crystallographic information is available from OCA.
ReferenceReference
Structural determinants of metal specificity in the zinc transport protein ZnuA from synechocystis 6803., Banerjee S, Wei B, Bhattacharyya-Pakrasi M, Pakrasi HB, Smith TJ, J Mol Biol. 2003 Nov 7;333(5):1061-9. PMID:14583199
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