1d7a: Difference between revisions

Revision as of 13:13, 21 February 2008

CRYSTAL STRUCTURE OF E. COLI PURE-MONONUCLEOTIDE COMPLEX.

OverviewOverview

BACKGROUND: Conversion of 5-aminoimidazole ribonucleotide (AIR) to 4-carboxyaminoimidazole ribonucleotide (CAIR) in Escherichia coli requires two proteins - PurK and PurE. PurE has recently been shown to be a mutase that catalyzes the unusual rearrangement of N(5)-carboxyaminoimidazole ribonucleotide (N(5)-CAIR), the PurK reaction product, to CAIR. PurEs from higher eukaryotes are homologous to E. coli PurE, but use AIR and CO(2) as substrates to produce CAIR directly. RESULTS: The 1.50 A crystal structure of PurE reveals an octameric structure with 422 symmetry. A central three-layer (alphabetaalpha) sandwich domain and a kinked C-terminal helix form the folded structure of the monomeric unit. The structure reveals a cleft at the interface of two subunits and near the C-terminal helix of a third subunit. Co-crystallization experiments with CAIR confirm this to be the mononucleotide-binding site. The nucleotide is bound predominantly to one subunit, with conserved residues from a second subunit making up one wall of the cleft. CONCLUSIONS: The crystal structure of PurE reveals a unique quaternary structure that confirms the octameric nature of the enzyme. An analysis of the native crystal structure, in conjunction with sequence alignments and studies of co-crystals of PurE with CAIR, reveals the location of the active site. The environment of the active site and the analysis of conserved residues between the two classes of PurEs suggests a model for the differences in their substrate specificities and the relationship between their mechanisms.

About this StructureAbout this Structure

1D7A is a Single protein structure of sequence from Escherichia coli with as ligand. Active as Phosphoribosylaminoimidazole carboxylase, with EC number 4.1.1.21 Full crystallographic information is available from OCA.

ReferenceReference

Crystal structure of Escherichia coli PurE, an unusual mutase in the purine biosynthetic pathway., Mathews II, Kappock TJ, Stubbe J, Ealick SE, Structure. 1999 Nov 15;7(11):1395-406. PMID:10574791

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-[[Image:1d7a.jpg|left|200px]]<br /><applet load="1d7a" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1d7a.jpg|left|200px]]<br /><applet load="1d7a" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1d7a, resolution 2.5&Aring;" />
 '''CRYSTAL STRUCTURE OF E. COLI PURE-MONONUCLEOTIDE COMPLEX.'''<br />
 ==Overview==
-BACKGROUND: Conversion of 5-aminoimidazole ribonucleotide (AIR) to, 4-carboxyaminoimidazole ribonucleotide (CAIR) in Escherichia coli requires, two proteins - PurK and PurE. PurE has recently been shown to be a mutase, that catalyzes the unusual rearrangement of N(5)-carboxyaminoimidazole, ribonucleotide (N(5)-CAIR), the PurK reaction product, to CAIR. PurEs from, higher eukaryotes are homologous to E. coli PurE, but use AIR and CO(2) as, substrates to produce CAIR directly. RESULTS: The 1.50 A crystal structure, of PurE reveals an octameric structure with 422 symmetry. A central, three-layer (alphabetaalpha) sandwich domain and a kinked C-terminal helix, form the folded structure of the monomeric unit. The structure reveals a, cleft at the interface of two subunits and near the C-terminal helix of a, third subunit. Co-crystallization experiments with CAIR confirm this to be, the mononucleotide-binding site. The nucleotide is bound predominantly to, one subunit, with conserved residues from a second subunit making up one, wall of the cleft. CONCLUSIONS: The crystal structure of PurE reveals a, unique quaternary structure that confirms the octameric nature of the, enzyme. An analysis of the native crystal structure, in conjunction with, sequence alignments and studies of co-crystals of PurE with CAIR, reveals, the location of the active site. The environment of the active site and, the analysis of conserved residues between the two classes of PurEs, suggests a model for the differences in their substrate specificities and, the relationship between their mechanisms.
+BACKGROUND: Conversion of 5-aminoimidazole ribonucleotide (AIR) to 4-carboxyaminoimidazole ribonucleotide (CAIR) in Escherichia coli requires two proteins - PurK and PurE. PurE has recently been shown to be a mutase that catalyzes the unusual rearrangement of N(5)-carboxyaminoimidazole ribonucleotide (N(5)-CAIR), the PurK reaction product, to CAIR. PurEs from higher eukaryotes are homologous to E. coli PurE, but use AIR and CO(2) as substrates to produce CAIR directly. RESULTS: The 1.50 A crystal structure of PurE reveals an octameric structure with 422 symmetry. A central three-layer (alphabetaalpha) sandwich domain and a kinked C-terminal helix form the folded structure of the monomeric unit. The structure reveals a cleft at the interface of two subunits and near the C-terminal helix of a third subunit. Co-crystallization experiments with CAIR confirm this to be the mononucleotide-binding site. The nucleotide is bound predominantly to one subunit, with conserved residues from a second subunit making up one wall of the cleft. CONCLUSIONS: The crystal structure of PurE reveals a unique quaternary structure that confirms the octameric nature of the enzyme. An analysis of the native crystal structure, in conjunction with sequence alignments and studies of co-crystals of PurE with CAIR, reveals the location of the active site. The environment of the active site and the analysis of conserved residues between the two classes of PurEs suggests a model for the differences in their substrate specificities and the relationship between their mechanisms.
 ==About this Structure==
-D7A is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with AIR as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Phosphoribosylaminoimidazole_carboxylase Phosphoribosylaminoimidazole carboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.21 4.1.1.21] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1D7A OCA].
+D7A is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with <scene name='pdbligand=AIR:'>AIR</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Phosphoribosylaminoimidazole_carboxylase Phosphoribosylaminoimidazole carboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.21 4.1.1.21] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1D7A OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Phosphoribosylaminoimidazole carboxylase]]
 [[Category: Single protein]]
-[[Category: Ealick, S.E.]]
+[[Category: Ealick, S E.]]
-[[Category: Kappock, T.J.]]
+[[Category: Kappock, T J.]]
-[[Category: Mathews, I.I.]]
+[[Category: Mathews, I I.]]
 [[Category: Stubbe, J.]]
 [[Category: AIR]]
@@ Line 22: / Line 22: @@
 [[Category: three-layer (alpha-beta-alpha) sandwich n5-cair mutase (pure)]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 13:03:44 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:13:42 2008''