2hz8

From Proteopedia

(Difference between revisions)
Jump to: navigation, search
Line 4: Line 4:
==Overview==
==Overview==
-
The de novo design of di-iron proteins is an important step towards understanding the diversity of function among this complex family of metalloenzymes. Previous designs of due ferro (DF) proteins have resulted in tetrameric and dimeric four-helix bundles having crystallographically well-defined structures and active-site geometries. Here, the design and characterization of DFsc, a 114 residue monomeric four-helix bundle, is presented. The backbone was modeled using previous oligomeric structures and appropriate inter-helical turns. The identities of 26 residues were predetermined, including the primary and secondary ligands in the active site, residues involved in active site accessibility, and the gamma beta gamma beta turn between helices 2 and 3. The remaining 88 amino acid residues were determined using statistical computer aided design, which is based upon a recent statistical theory of protein sequences. Rather than sampling sequences, the theory directly provides the site-specific amino acid probabilities, which are then used to guide sequence design. The resulting sequence (DFsc) expresses well in Escherichia coli and is highly soluble. Sedimentation studies confirm that the protein is monomeric in solution. Circular dichroism spectra are consistent with the helical content of the target structure. The protein is structured in both the apo and the holo forms, with the metal-bound form exhibiting increased stability. DFsc stoichiometrically binds a variety of divalent metal ions, including Zn(II), Co(II), Fe(II), and Mn(II), with micromolar affinities. 15N HSQC NMR spectra of both the apo and Zn(II) proteins reveal excellent dispersion with evidence of a significant structural change upon metal binding. DFsc is then a realization of complete de novo design, where backbone structure, activity, and sequence are specified in the design process.
+
We report the solution NMR structure of a designed dimetal-binding protein, di-Zn(II) DFsc, along with a secondary refinement step employing molecular dynamics techniques. Calculation of the initial NMR structural ensemble by standard methods led to distortions in the metal-ligand geometries at the active site. Unrestrained molecular dynamics using a nonbonded force field for the metal shell, followed by quantum mechanical/molecular mechanical dynamics of DFsc, were used to relax local frustrations at the dimetal site that were apparent in the initial NMR structure and provide a more realistic description of the structure. The MD model is consistent with NMR restraints, and in good agreement with the structural and functional properties expected for DF proteins. This work demonstrates that NMR structures of metalloproteins can be further refined using classical and first-principles molecular dynamics methods in the presence of explicit solvent to provide otherwise unavailable insight into the geometry of the metal center.
==About this Structure==
==About this Structure==
-
2HZ8 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] 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=2HZ8 OCA].
+
2HZ8 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Known structural/functional Sites: <scene name='pdbsite=AC1:Zn+Binding+Site+For+Residue+A+116'>AC1</scene> and <scene name='pdbsite=AC2:Zn+Binding+Site+For+Residue+A+117'>AC2</scene>. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HZ8 OCA].
==Reference==
==Reference==
-
Computational design and characterization of a monomeric helical dinuclear metalloprotein., Calhoun JR, Kono H, Lahr S, Wang W, DeGrado WF, Saven JG, J Mol Biol. 2003 Dec 12;334(5):1101-15. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14643669 14643669]
+
Solution NMR structure of a designed metalloprotein and complementary molecular dynamics refinement., Calhoun JR, Liu W, Spiegel K, Dal Peraro M, Klein ML, Valentine KG, Wand AJ, Degrado WF, Structure. 2008 Feb;16(2):210-5. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=18275812 18275812]
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Protein complex]]
[[Category: Protein complex]]
Line 21: Line 21:
[[Category: Wand, A J.]]
[[Category: Wand, A J.]]
[[Category: ZN]]
[[Category: ZN]]
 +
[[Category: de novo protein]]
[[Category: four-helix bundle]]
[[Category: four-helix bundle]]
-
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:47:27 2008''
+
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Mar 14 09:42:32 2008''

Revision as of 07:42, 14 March 2008


2hz8

Drag the structure with the mouse to rotate

QM/MM structure refined from NMR-structure of a single chain diiron protein

Overview

We report the solution NMR structure of a designed dimetal-binding protein, di-Zn(II) DFsc, along with a secondary refinement step employing molecular dynamics techniques. Calculation of the initial NMR structural ensemble by standard methods led to distortions in the metal-ligand geometries at the active site. Unrestrained molecular dynamics using a nonbonded force field for the metal shell, followed by quantum mechanical/molecular mechanical dynamics of DFsc, were used to relax local frustrations at the dimetal site that were apparent in the initial NMR structure and provide a more realistic description of the structure. The MD model is consistent with NMR restraints, and in good agreement with the structural and functional properties expected for DF proteins. This work demonstrates that NMR structures of metalloproteins can be further refined using classical and first-principles molecular dynamics methods in the presence of explicit solvent to provide otherwise unavailable insight into the geometry of the metal center.

About this Structure

2HZ8 is a Protein complex structure of sequences from Escherichia coli with as ligand. Known structural/functional Sites: and . Full crystallographic information is available from OCA.

Reference

Solution NMR structure of a designed metalloprotein and complementary molecular dynamics refinement., Calhoun JR, Liu W, Spiegel K, Dal Peraro M, Klein ML, Valentine KG, Wand AJ, Degrado WF, Structure. 2008 Feb;16(2):210-5. PMID:18275812

Page seeded by OCA on Fri Mar 14 09:42:32 2008

Proteopedia Page Contributors and Editors (what is this?)

OCA

Personal tools