1k0f
From Proteopedia
(New page: 200px<br /><applet load="1k0f" size="450" color="white" frame="true" align="right" spinBox="true" caption="1k0f, resolution 2.5Å" /> '''Crystal structure of ...) |
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| - | [[Image:1k0f.gif|left|200px]]<br /><applet load="1k0f" size=" | + | [[Image:1k0f.gif|left|200px]]<br /><applet load="1k0f" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1k0f, resolution 2.5Å" /> | caption="1k0f, resolution 2.5Å" /> | ||
'''Crystal structure of Zn(II)-free T. pallidum TroA'''<br /> | '''Crystal structure of Zn(II)-free T. pallidum TroA'''<br /> | ||
==Overview== | ==Overview== | ||
| - | We previously demonstrated that Treponema pallidum TroA is a periplasmic | + | We previously demonstrated that Treponema pallidum TroA is a periplasmic metal-binding protein (MBP) with a distinctive alpha-helical backbone. To better understand the mechanisms of metal binding and release by TroA, we determined the crystal structure of the apoprotein at a resolution of 2.5 A and compared it to that of the Zn(II)-bound form (Protein Data Bank accession code 1toa). apo-TroA shows a conformation even more closed than that of its Zn(II)-bound counterpart due to a 4 degrees tilt of the C-terminal domain (residues 190 through 308) about an axis parallel to the poorly flexible backbone helix. This domain tilting pushes two loops (residues 248 through 253 and 277 through 286) towards the metal-binding site by more than 1 A, resulting in an unfavorable interaction of I251 with D66. To avoid this contact, D66 shifts towards H68, one of the four Zn(II)-coordinating residues. The approach of this negative charge coincides with the flipping of the imidazole side chain of H68, resulting in the formation of a new hydrogen bond. The conformational change of H68, along with a slight rearrangement of D279, a C-terminal domain Zn(II)-coordinating residue, distorts the metal-binding site geometry, presumably causing the release of the bound metal ion. Ligand binding and release by TroA, and presumably by other members of the MBP cluster, differs from the "Venus flytrap" mechanism utilized by bacterial nonmetal solute-binding receptors. |
==About this Structure== | ==About this Structure== | ||
| - | 1K0F is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Treponema_pallidum Treponema pallidum]. Full crystallographic information is available from [http:// | + | 1K0F is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Treponema_pallidum Treponema pallidum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K0F OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Treponema pallidum]] | [[Category: Treponema pallidum]] | ||
| - | [[Category: Deka, R | + | [[Category: Deka, R K.]] |
| - | [[Category: Dorwart, M | + | [[Category: Dorwart, M R.]] |
| - | [[Category: Hasemann, C | + | [[Category: Hasemann, C A.]] |
| - | [[Category: Hazlett, K | + | [[Category: Hazlett, K R.]] |
| - | [[Category: Lee, Y | + | [[Category: Lee, Y H.]] |
| - | [[Category: Norgard, M | + | [[Category: Norgard, M V.]] |
| - | [[Category: Radolf, J | + | [[Category: Radolf, J D.]] |
[[Category: apo protein]] | [[Category: apo protein]] | ||
[[Category: closed conformation]] | [[Category: closed conformation]] | ||
[[Category: helix backbone]] | [[Category: helix backbone]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:28:43 2008'' |
Revision as of 11:28, 21 February 2008
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Crystal structure of Zn(II)-free T. pallidum TroA
Overview
We previously demonstrated that Treponema pallidum TroA is a periplasmic metal-binding protein (MBP) with a distinctive alpha-helical backbone. To better understand the mechanisms of metal binding and release by TroA, we determined the crystal structure of the apoprotein at a resolution of 2.5 A and compared it to that of the Zn(II)-bound form (Protein Data Bank accession code 1toa). apo-TroA shows a conformation even more closed than that of its Zn(II)-bound counterpart due to a 4 degrees tilt of the C-terminal domain (residues 190 through 308) about an axis parallel to the poorly flexible backbone helix. This domain tilting pushes two loops (residues 248 through 253 and 277 through 286) towards the metal-binding site by more than 1 A, resulting in an unfavorable interaction of I251 with D66. To avoid this contact, D66 shifts towards H68, one of the four Zn(II)-coordinating residues. The approach of this negative charge coincides with the flipping of the imidazole side chain of H68, resulting in the formation of a new hydrogen bond. The conformational change of H68, along with a slight rearrangement of D279, a C-terminal domain Zn(II)-coordinating residue, distorts the metal-binding site geometry, presumably causing the release of the bound metal ion. Ligand binding and release by TroA, and presumably by other members of the MBP cluster, differs from the "Venus flytrap" mechanism utilized by bacterial nonmetal solute-binding receptors.
About this Structure
1K0F is a Single protein structure of sequence from Treponema pallidum. Full crystallographic information is available from OCA.
Reference
The crystal structure of Zn(II)-free Treponema pallidum TroA, a periplasmic metal-binding protein, reveals a closed conformation., Lee YH, Dorwart MR, Hazlett KR, Deka RK, Norgard MV, Radolf JD, Hasemann CA, J Bacteriol. 2002 Apr;184(8):2300-4. PMID:11914363
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