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1x08

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[[Image:1x08.gif|left|200px]]
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{{STRUCTURE_1x08| PDB=1x08 | SCENE= }}
{{STRUCTURE_1x08| PDB=1x08 | SCENE= }}
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'''Crystal structure of D26A mutant UPPs in complex with Mg, IPP and FsPP'''
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===Crystal structure of D26A mutant UPPs in complex with Mg, IPP and FsPP===
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==Overview==
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Undecaprenyl pyrophosphate synthase (UPPs) catalyzes the consecutive condensation reactions of a farnesyl pyrophosphate (FPP) with eight isopentenyl pyrophosphates (IPP), in which new cis-double bonds are formed, to generate undecaprenyl pyrophosphate that serves as a lipid carrier for peptidoglycan synthesis of bacterial cell wall. The structures of Escherichia coli UPPs were determined previously in an orthorhombic crystal form as an apoenzyme, in complex with Mg(2+)/sulfate/Triton, and with bound FPP. In a further search of its catalytic mechanism, the wild-type UPPs and the D26A mutant are crystallized in a new trigonal unit cell with Mg(2+)/IPP/farnesyl thiopyrophosphate (an FPP analogue) bound to the active site. In the wild-type enzyme, Mg(2+) is coordinated by the pyrophosphate of farnesyl thiopyrophosphate, the carboxylate of Asp(26), and three water molecules. In the mutant enzyme, it is bound to the pyrophosphate of IPP. The [Mg(2+)] dependence of the catalytic rate by UPPs shows that the activity is maximal at [Mg(2+)] = 1 mm but drops significantly when Mg(2+) ions are in excess (50 mm). Without Mg(2+), IPP binds to UPPs only at high concentration. Mutation of Asp(26) to other charged amino acids results in significant decrease of the UPPs activity. The role of Asp(26) is probably to assist the migration of Mg(2+) from IPP to FPP and thus initiate the condensation reaction by ionization of the pyrophosphate group from FPP. Other conserved residues, including His(43), Ser(71), Asn(74), and Arg(77), may serve as general acid/base and pyrophosphate carrier. Our results here improve the understanding of the UPPs enzyme reaction significantly.
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{{ABSTRACT_PUBMED_15788389}}
==About this Structure==
==About this Structure==
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[[Category: Wang, A H.J.]]
[[Category: Wang, A H.J.]]
[[Category: Inactive mutant enzyme-substrate complex]]
[[Category: Inactive mutant enzyme-substrate complex]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 14:22:12 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 13:14:50 2008''

Revision as of 10:14, 29 July 2008

Image:1x08.png

Template:STRUCTURE 1x08

Crystal structure of D26A mutant UPPs in complex with Mg, IPP and FsPP

Template:ABSTRACT PUBMED 15788389

About this Structure

1X08 is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.

Reference

Crystal structures of undecaprenyl pyrophosphate synthase in complex with magnesium, isopentenyl pyrophosphate, and farnesyl thiopyrophosphate: roles of the metal ion and conserved residues in catalysis., Guo RT, Ko TP, Chen AP, Kuo CJ, Wang AH, Liang PH, J Biol Chem. 2005 May 27;280(21):20762-74. Epub 2005 Mar 23. PMID:15788389

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