2fw6
From Proteopedia
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| - | [[Image:2fw6.gif|left|200px]] | + | [[Image:2fw6.gif|left|200px]] |
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| - | '''Structure of PurE (N5-carboxyaminoimidazole ribonucleotide mutase) mutant H59N from the acidophilic bacterium Acetobacter aceti, at pH 5.4''' | + | {{Structure |
| + | |PDB= 2fw6 |SIZE=350|CAPTION= <scene name='initialview01'>2fw6</scene>, resolution 1.85Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=CIT:CITRIC ACID'>CIT</scene> | ||
| + | |ACTIVITY= | ||
| + | |GENE= purE ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=435 Acetobacter aceti]) | ||
| + | }} | ||
| + | |||
| + | '''Structure of PurE (N5-carboxyaminoimidazole ribonucleotide mutase) mutant H59N from the acidophilic bacterium Acetobacter aceti, at pH 5.4''' | ||
| + | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 2FW6 is a [ | + | 2FW6 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Acetobacter_aceti Acetobacter aceti]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2FW6 OCA]. |
==Reference== | ==Reference== | ||
| - | Biochemical and structural studies of N5-carboxyaminoimidazole ribonucleotide mutase from the acidophilic bacterium Acetobacter aceti., Constantine CZ, Starks CM, Mill CP, Ransome AE, Karpowicz SJ, Francois JA, Goodman RA, Kappock TJ, Biochemistry. 2006 Jul 11;45(27):8193-208. PMID:[http:// | + | Biochemical and structural studies of N5-carboxyaminoimidazole ribonucleotide mutase from the acidophilic bacterium Acetobacter aceti., Constantine CZ, Starks CM, Mill CP, Ransome AE, Karpowicz SJ, Francois JA, Goodman RA, Kappock TJ, Biochemistry. 2006 Jul 11;45(27):8193-208. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16819818 16819818] |
[[Category: Acetobacter aceti]] | [[Category: Acetobacter aceti]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: purine biosynthesis]] | [[Category: purine biosynthesis]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 16:57:26 2008'' |
Revision as of 14:57, 20 March 2008
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| , resolution 1.85Å | |||||||
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| Ligands: | |||||||
| Gene: | purE (Acetobacter aceti) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structure of PurE (N5-carboxyaminoimidazole ribonucleotide mutase) mutant H59N from the acidophilic bacterium Acetobacter aceti, at pH 5.4
Overview
N5-carboxyaminoimidazole ribonucleotide (N5-CAIR) mutase (PurE) catalyzes the reversible interconversion of acid-labile compounds N5-CAIR and 4-carboxy-5-aminoimidazole ribonucleotide (CAIR). We have examined PurE from the acidophilic bacterium Acetobacter aceti (AaPurE), focusing on its adaptation to acid pH and the roles of conserved residues His59 and His89. Both AaPurE and Escherichia coli PurE showed quasi-reversible acid-mediated inactivation, but wt AaPurE was much more stable at pH 3.5, with a > or = 20 degrees C higher thermal unfolding temperature at all pHs. His89 is not essential and does not function as part of a proton relay system. The kcat pH-rate profile was consistent with the assignment of pK1 to unproductive protonation of bound nucleotide and pK2 to deprotonation of His59. A 1.85 A resolution crystal structure of the inactive mutant H59N-AaPurE soaked in CAIR showed that protonation of CAIR C4 can occur in the absence of His59. The resulting species, modeled as isoCAIR [4(R)-carboxy-5-iminoimidazoline ribonucleotide], is strongly stabilized by extensive interactions with the enzyme and a water molecule. The carboxylate moiety is positioned in a small pocket proposed to facilitate nucleotide decarboxylation in the forward direction (N5-CAIR --> CAIR) [Meyer, E., Kappock, T. J., Osuji, C., and Stubbe, J. (1999) Biochemistry 38, 3012-3018]. Comparisons with model studies suggest that in the reverse (nonbiosynthetic) direction PurE favors protonation of CAIR C4. We suggest that the essential role of protonated His59 is to lower the barrier to decarboxylation by stabilizing a CO2-azaenolate intermediate.
About this Structure
2FW6 is a Single protein structure of sequence from Acetobacter aceti. Full crystallographic information is available from OCA.
Reference
Biochemical and structural studies of N5-carboxyaminoimidazole ribonucleotide mutase from the acidophilic bacterium Acetobacter aceti., Constantine CZ, Starks CM, Mill CP, Ransome AE, Karpowicz SJ, Francois JA, Goodman RA, Kappock TJ, Biochemistry. 2006 Jul 11;45(27):8193-208. PMID:16819818
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