1zm8

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(New page: 200px<br /><applet load="1zm8" size="450" color="white" frame="true" align="right" spinBox="true" caption="1zm8, resolution 1.90&Aring;" /> '''Apo Crystal structur...)
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'''Apo Crystal structure of Nuclease A from Anabaena sp.'''<br />
'''Apo Crystal structure of Nuclease A from Anabaena sp.'''<br />
==Overview==
==Overview==
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Nuclease A (NucA) is a nonspecific endonuclease from Anabaena sp. capable, of degrading single- and double-stranded DNA and RNA in the presence of, divalent metal ions. We have determined the structure of the, delta(2-24),D121A mutant of NucA in the presence of Zn2+ and Mn2+ (PDB, code 1ZM8). The mutations were introduced to remove the N-terminal signal, peptide and to reduce the activity of the nonspecific nuclease, thereby, reducing its toxicity to the Escherichia coli expression system. NucA, contains a betabeta alpha metal finger motif and a hydrated Mn2+ ion at, the active site. Unexpectedly, NucA was found to contain additional metal, binding sites approximately 26 A apart from the catalytic metal binding, site. A structural comparison between NucA and the closest analog for, which structural data exist, the Serratia nuclease, indicates several, interesting differences. First, NucA is a monomer rather than a dimer., Second, there is an unexpected structural homology between the N-terminal, segments despite a poorly conserved sequence, which in Serratia includes a, cysteine bridge thought to play a regulatory role. In addition, although a, sequence alignment had suggested that NucA lacks a proposed catalytic, residue corresponding to Arg57 in Serratia, the structure determined here, indicates that Arg93 in NucA is positioned to fulfill this role. Based on, comparison with DNA-bound nuclease structures of the betabeta alpha metal, finger nuclease family and available mutational data on NucA, we propose, that His124 acts as a catalytic base, and Arg93 participates in the, catalysis possibly through stabilization of the transition state.
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Nuclease A (NucA) is a nonspecific endonuclease from Anabaena sp. capable of degrading single- and double-stranded DNA and RNA in the presence of divalent metal ions. We have determined the structure of the delta(2-24),D121A mutant of NucA in the presence of Zn2+ and Mn2+ (PDB code 1ZM8). The mutations were introduced to remove the N-terminal signal peptide and to reduce the activity of the nonspecific nuclease, thereby reducing its toxicity to the Escherichia coli expression system. NucA contains a betabeta alpha metal finger motif and a hydrated Mn2+ ion at the active site. Unexpectedly, NucA was found to contain additional metal binding sites approximately 26 A apart from the catalytic metal binding site. A structural comparison between NucA and the closest analog for which structural data exist, the Serratia nuclease, indicates several interesting differences. First, NucA is a monomer rather than a dimer. Second, there is an unexpected structural homology between the N-terminal segments despite a poorly conserved sequence, which in Serratia includes a cysteine bridge thought to play a regulatory role. In addition, although a sequence alignment had suggested that NucA lacks a proposed catalytic residue corresponding to Arg57 in Serratia, the structure determined here indicates that Arg93 in NucA is positioned to fulfill this role. Based on comparison with DNA-bound nuclease structures of the betabeta alpha metal finger nuclease family and available mutational data on NucA, we propose that His124 acts as a catalytic base, and Arg93 participates in the catalysis possibly through stabilization of the transition state.
==About this Structure==
==About this Structure==
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1ZM8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Anabaena_sp. Anabaena sp.] with MN, SO4 and NA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1ZM8 OCA].
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1ZM8 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Anabaena_sp. Anabaena sp.] with <scene name='pdbligand=MN:'>MN</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=NA:'>NA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ZM8 OCA].
==Reference==
==Reference==
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[[Category: Single protein]]
[[Category: Single protein]]
[[Category: Ghosh, M.]]
[[Category: Ghosh, M.]]
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[[Category: London, R.E.]]
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[[Category: London, R E.]]
[[Category: Meiss, G.]]
[[Category: Meiss, G.]]
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[[Category: Pedersen, L.C.]]
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[[Category: Pedersen, L C.]]
[[Category: Pingoud, A.]]
[[Category: Pingoud, A.]]
[[Category: MN]]
[[Category: MN]]
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[[Category: nuclease]]
[[Category: nuclease]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 07:32:02 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:16:56 2008''

Revision as of 14:16, 21 February 2008

Image:1zm8.gif

1zm8, resolution 1.90Å

Drag the structure with the mouse to rotate

Apo Crystal structure of Nuclease A from Anabaena sp.

Overview

Nuclease A (NucA) is a nonspecific endonuclease from Anabaena sp. capable of degrading single- and double-stranded DNA and RNA in the presence of divalent metal ions. We have determined the structure of the delta(2-24),D121A mutant of NucA in the presence of Zn2+ and Mn2+ (PDB code 1ZM8). The mutations were introduced to remove the N-terminal signal peptide and to reduce the activity of the nonspecific nuclease, thereby reducing its toxicity to the Escherichia coli expression system. NucA contains a betabeta alpha metal finger motif and a hydrated Mn2+ ion at the active site. Unexpectedly, NucA was found to contain additional metal binding sites approximately 26 A apart from the catalytic metal binding site. A structural comparison between NucA and the closest analog for which structural data exist, the Serratia nuclease, indicates several interesting differences. First, NucA is a monomer rather than a dimer. Second, there is an unexpected structural homology between the N-terminal segments despite a poorly conserved sequence, which in Serratia includes a cysteine bridge thought to play a regulatory role. In addition, although a sequence alignment had suggested that NucA lacks a proposed catalytic residue corresponding to Arg57 in Serratia, the structure determined here indicates that Arg93 in NucA is positioned to fulfill this role. Based on comparison with DNA-bound nuclease structures of the betabeta alpha metal finger nuclease family and available mutational data on NucA, we propose that His124 acts as a catalytic base, and Arg93 participates in the catalysis possibly through stabilization of the transition state.

About this Structure

1ZM8 is a Single protein structure of sequence from Anabaena sp. with , and as ligands. Full crystallographic information is available from OCA.

Reference

Structural insights into the mechanism of nuclease A, a betabeta alpha metal nuclease from Anabaena., Ghosh M, Meiss G, Pingoud A, London RE, Pedersen LC, J Biol Chem. 2005 Jul 29;280(30):27990-7. Epub 2005 May 15. PMID:15897201

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