1k0e
From Proteopedia
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| - | [[Image:1k0e.jpg|left|200px]] | + | [[Image:1k0e.jpg|left|200px]] |
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| - | '''THE CRYSTAL STRUCTURE OF AMINODEOXYCHORISMATE SYNTHASE FROM FORMATE GROWN CRYSTALS''' | + | {{Structure |
| + | |PDB= 1k0e |SIZE=350|CAPTION= <scene name='initialview01'>1k0e</scene>, resolution 2.00Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=TRP:TRYPTOPHAN'>TRP</scene> and <scene name='pdbligand=FMT:FORMIC ACID'>FMT</scene> | ||
| + | |ACTIVITY= | ||
| + | |GENE= | ||
| + | }} | ||
| + | |||
| + | '''THE CRYSTAL STRUCTURE OF AMINODEOXYCHORISMATE SYNTHASE FROM FORMATE GROWN CRYSTALS''' | ||
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==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1K0E is a [ | + | 1K0E is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K0E OCA]. |
==Reference== | ==Reference== | ||
| - | Structure of Escherichia coli aminodeoxychorismate synthase: architectural conservation and diversity in chorismate-utilizing enzymes., Parsons JF, Jensen PY, Pachikara AS, Howard AJ, Eisenstein E, Ladner JE, Biochemistry. 2002 Feb 19;41(7):2198-208. PMID:[http:// | + | Structure of Escherichia coli aminodeoxychorismate synthase: architectural conservation and diversity in chorismate-utilizing enzymes., Parsons JF, Jensen PY, Pachikara AS, Howard AJ, Eisenstein E, Ladner JE, Biochemistry. 2002 Feb 19;41(7):2198-208. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/11841211 11841211] |
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: tryptophan]] | [[Category: tryptophan]] | ||
| - | ''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 12:10:52 2008'' |
Revision as of 10:10, 20 March 2008
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| Ligands: | and | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
THE CRYSTAL STRUCTURE OF AMINODEOXYCHORISMATE SYNTHASE FROM FORMATE GROWN CRYSTALS
Overview
Aminodeoxychorismate synthase is part of a heterodimeric complex that catalyzes the two-step biosynthesis of 4-amino-4-deoxychorismate, a precursor of p-aminobenzoate and folate in microorganisms. In the first step, a glutamine amidotransferase encoded by the pabA gene generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by aminodeoxychorismate synthase, the product of the pabB gene. Here we report the X-ray crystal structure of Escherichia coli PabB determined in two different crystal forms, each at 2.0 A resolution. The 453-residue monomeric PabB has a complex alpha/beta fold which is similar to that seen in the structures of homologous, oligomeric TrpE subunits of several anthranilate synthases of microbial origin. A comparison of the structures of these two classes of chorismate-utilizing enzymes provides a rationale for the differences in quaternary structures seen for these enzymes, and indicates that the weak or transient association of PabB with PabA during catalysis stems at least partly from a limited interface for protein interactions. Additional analyses of the structures enabled the tentative identification of the active site of PabB, which contains a number of residues implicated from previous biochemical and genetic studies to be essential for activity. Differences in the structures determined from phosphate- and formate-grown crystals, and the location of an adventitious formate ion, suggest that conformational changes in loop regions adjacent to the active site may be needed for catalysis. A surprising finding in the structure of PabB was the presence of a tryptophan molecule deeply embedded in a binding pocket that is analogous to the regulatory site in the TrpE subunits of the anthranilate synthases. The strongly bound ligand, which cannot be dissociated without denaturation of PabB, may play a structural role in the enzyme since there is no effect of tryptophan on the enzymic synthesis of aminodeoxychorismate. Extensive sequence similarity in the tryptophan-binding pocket among several other chorismate-utilizing enzymes, including isochorismate synthase, suggests that they too may bind tryptophan for structural integrity, and corroborates early ideas on the evolution of this interesting enzyme family.
About this Structure
1K0E is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure of Escherichia coli aminodeoxychorismate synthase: architectural conservation and diversity in chorismate-utilizing enzymes., Parsons JF, Jensen PY, Pachikara AS, Howard AJ, Eisenstein E, Ladner JE, Biochemistry. 2002 Feb 19;41(7):2198-208. PMID:11841211
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