1n8f: Difference between revisions

Revision as of 15:03, 21 February 2008

Crystal structure of E24Q mutant of phenylalanine-regulated 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP synthase) from Escherichia Coli in complex with Mn2+ and PEP

OverviewOverview

3-Deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS), the first enzyme of the aromatic biosynthetic pathway in microorganisms and plants, catalyzes the aldol-like condensation of phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P) with the formation of DAHP. The native and the selenomethionine-substituted forms of the phenylalanine-regulated isozyme [DAHPS(Phe)] from Escherichia coli were crystallized in complex with PEP and a metal cofactor, Mn(2+), but the crystals displayed disorder in their unit cells, preventing satisfactory refinement. However, the crystal structure of the E24Q mutant form of DAHPS(Phe) in complex with PEP and Mn(2+) has been determined at 1.75 A resolution. Unlike the tetrameric wild-type enzyme, the E24Q enzyme is dimeric in solution, as a result of the mutational perturbation of four intersubunit salt bridges that are critical for tetramer formation. The protein chain conformation and subunit arrangement in the crystals of E24Q and wild-type DAHPS are very similar. However, the interaction of Mn(2+) and PEP in the enzymatically active E24Q mutant complex differs from the Pb(2+)-PEP and Mn(2+)-phosphoglycolate interactions in two enzymatically inactive wild-type complexes whose structures have been determined previously. The geometry of PEP bound in the active site of the E24Q enzyme deviates from planarity due to a 30 degrees twist of the carboxylate plane relative to the enol plane. In addition, seven water molecules are within contact distance of PEP, two of which are close enough to its C2 atom to serve as the nucleophile required in the reaction.

About this StructureAbout this Structure

1N8F is a Single protein structure of sequence from Escherichia coli with , and as ligands. Active as 3-deoxy-7-phosphoheptulonate synthase, with EC number 2.5.1.54 Full crystallographic information is available from OCA.

ReferenceReference

The high-resolution structure of 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase reveals a twist in the plane of bound phosphoenolpyruvate., Shumilin IA, Bauerle R, Kretsinger RH, Biochemistry. 2003 Apr 8;42(13):3766-76. PMID:12667068

Page seeded by OCA on Thu Feb 21 14:03:20 2008

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-[[Image:1n8f.gif|left|200px]]<br /><applet load="1n8f" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1n8f.gif|left|200px]]<br /><applet load="1n8f" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1n8f, resolution 1.75&Aring;" />
 '''Crystal structure of E24Q mutant of phenylalanine-regulated 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHP synthase) from Escherichia Coli in complex with Mn2+ and PEP'''<br />
 ==Overview==
--Deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS), the first, enzyme of the aromatic biosynthetic pathway in microorganisms and plants, catalyzes the aldol-like condensation of phosphoenolpyruvate (PEP) and, D-erythrose 4-phosphate (E4P) with the formation of DAHP. The native and, the selenomethionine-substituted forms of the phenylalanine-regulated, isozyme [DAHPS(Phe)] from Escherichia coli were crystallized in complex, with PEP and a metal cofactor, Mn(2+), but the crystals displayed disorder, in their unit cells, preventing satisfactory refinement. However, the, crystal structure of the E24Q mutant form of DAHPS(Phe) in complex with, PEP and Mn(2+) has been determined at 1.75 A resolution. Unlike the, tetrameric wild-type enzyme, the E24Q enzyme is dimeric in solution, as a, result of the mutational perturbation of four intersubunit salt bridges, that are critical for tetramer formation. The protein chain conformation, and subunit arrangement in the crystals of E24Q and wild-type DAHPS are, very similar. However, the interaction of Mn(2+) and PEP in the, enzymatically active E24Q mutant complex differs from the Pb(2+)-PEP and, Mn(2+)-phosphoglycolate interactions in two enzymatically inactive, wild-type complexes whose structures have been determined previously. The, geometry of PEP bound in the active site of the E24Q enzyme deviates from, planarity due to a 30 degrees twist of the carboxylate plane relative to, the enol plane. In addition, seven water molecules are within contact, distance of PEP, two of which are close enough to its C2 atom to serve as, the nucleophile required in the reaction.
+-Deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS), the first enzyme of the aromatic biosynthetic pathway in microorganisms and plants, catalyzes the aldol-like condensation of phosphoenolpyruvate (PEP) and D-erythrose 4-phosphate (E4P) with the formation of DAHP. The native and the selenomethionine-substituted forms of the phenylalanine-regulated isozyme [DAHPS(Phe)] from Escherichia coli were crystallized in complex with PEP and a metal cofactor, Mn(2+), but the crystals displayed disorder in their unit cells, preventing satisfactory refinement. However, the crystal structure of the E24Q mutant form of DAHPS(Phe) in complex with PEP and Mn(2+) has been determined at 1.75 A resolution. Unlike the tetrameric wild-type enzyme, the E24Q enzyme is dimeric in solution, as a result of the mutational perturbation of four intersubunit salt bridges that are critical for tetramer formation. The protein chain conformation and subunit arrangement in the crystals of E24Q and wild-type DAHPS are very similar. However, the interaction of Mn(2+) and PEP in the enzymatically active E24Q mutant complex differs from the Pb(2+)-PEP and Mn(2+)-phosphoglycolate interactions in two enzymatically inactive wild-type complexes whose structures have been determined previously. The geometry of PEP bound in the active site of the E24Q enzyme deviates from planarity due to a 30 degrees twist of the carboxylate plane relative to the enol plane. In addition, seven water molecules are within contact distance of PEP, two of which are close enough to its C2 atom to serve as the nucleophile required in the reaction.
 ==About this Structure==
-N8F 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 MN, SO4 and PEP as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/3-deoxy-7-phosphoheptulonate_synthase 3-deoxy-7-phosphoheptulonate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.54 2.5.1.54] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1N8F OCA].
+N8F 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=MN:'>MN</scene>, <scene name='pdbligand=SO4:'>SO4</scene> and <scene name='pdbligand=PEP:'>PEP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/3-deoxy-7-phosphoheptulonate_synthase 3-deoxy-7-phosphoheptulonate synthase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.5.1.54 2.5.1.54] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N8F OCA].
 ==Reference==
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 [[Category: Single protein]]
 [[Category: Bauerle, R.]]
-[[Category: Kretsinger, R.H.]]
+[[Category: Kretsinger, R H.]]
-[[Category: Shumilin, I.A.]]
+[[Category: Shumilin, I A.]]
 [[Category: MN]]
 [[Category: PEP]]
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 [[Category: (beta/alpha)8 barrel]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 22:02:38 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:03:20 2008''