1qr7: Difference between revisions

|PDB= 1qr7 |SIZE=350|CAPTION= <scene name='initialview01'>1qr7</scene>, resolution 2.6&Aring;

|SITE=  

|LIGAND= <scene name='pdbligand=PB:LEAD+(II)+ION'>PB</scene>, <scene name='pdbligand=PEP:PHOSPHOENOLPYRUVATE'>PEP</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene>

|ACTIVITY= <span class='plainlinks'>[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] </span>

|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1qr7 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qr7 OCA], [http://www.ebi.ac.uk/pdbsum/1qr7 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1qr7 RCSB]</span>

 

 

==Overview==

BACKGROUND: In microorganisms and plants the first step in the common pathway leading to the biosynthesis of aromatic compounds is the stereospecific condensation of phosphoenolpyruvate (PEP) and D-erythrose-4-phosphate (E4P) giving rise to 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP). This reaction is catalyzed by DAHP synthase (DAHPS), a metal-activated enzyme, which in microorganisms is the target for negative-feedback regulation by pathway intermediates or by end products. In Escherichia coli there are three DAHPS isoforms, each specifically inhibited by one of the three aromatic amino acids. RESULTS: The crystal structure of the phenylalanine-regulated form of DAHPS complexed with PEP and Pb2+ (DAHPS(Phe)-PEP-Pb) was determined by multiple wavelength anomalous dispersion phasing utilizing the anomalous scattering of Pb2+. The tetramer consists of two tight dimers. The monomers of the tight dimer are coupled by extensive interactions including a pair of three-stranded, intersubunit beta sheets. The monomer (350 residues) is a (beta/alpha)8 barrel with several additional beta strands and alpha helices. The PEP and Pb2+ are at the C-ends of the beta strands of the barrel, as is SO4(2-), inferred to occupy the position of the phosphate of E4P. Mutations that reduce feedback inhibition cluster about a cavity near the twofold axis of the tight dimer and are centered approximately 15 A from the active site, indicating the location of a separate regulatory site. CONCLUSIONS: The crystal structure of DAHPS(Phe)-PEP-Pb reveals the active site of this key enzyme of aromatic biosynthesis and indicates the probable site of inhibitor binding. This is the first reported structure of a DAHPS; the structure of its two paralogs and of a variety of orthologs should now be readily determined by molecular replacement.

 

1QR7 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=1QR7 OCA].

 

Crystal structure of phenylalanine-regulated 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase from Escherichia coli., Shumilin IA, Kretsinger RH, Bauerle RH, Structure. 1999 Jul 15;7(7):865-75. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10425687 10425687]

[[Category: Single protein]]

[[Category: Bauerle, R H.]]

[[Category: Kretsinger, R H.]]

[[Category: Shumilin, I A.]]