1kbr: Difference between revisions
New page: left|200px<br /><applet load="1kbr" size="450" color="white" frame="true" align="right" spinBox="true" caption="1kbr, resolution 1.55Å" /> '''CRYSTAL STRUCTURE OF... |
No edit summary |
||
| Line 1: | Line 1: | ||
[[Image:1kbr.jpg|left|200px]]<br /><applet load="1kbr" size=" | [[Image:1kbr.jpg|left|200px]]<br /><applet load="1kbr" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1kbr, resolution 1.55Å" /> | caption="1kbr, resolution 1.55Å" /> | ||
'''CRYSTAL STRUCTURE OF UNLIGATED HPPK(R92A) FROM E.COLI AT 1.55 ANGSTROM RESOLUTION'''<br /> | '''CRYSTAL STRUCTURE OF UNLIGATED HPPK(R92A) FROM E.COLI AT 1.55 ANGSTROM RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the | 6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate biosynthetic pathway. Arginine residues 82 and 92, strictly conserved in 35 HPPK sequences, play dynamic roles in the catalytic cycle of the enzyme. At 0.89-A resolution, two distinct conformations are observed for each of the two residues in the crystal structure of the wild-type HPPK in complex with two HP variants, two Mg(2+) ions, and an ATP analogue. Structural information suggests that R92 first binds to the alpha-phosphate group of ATP and then shifts to interact with the beta-phosphate as R82, which initially does not bind to ATP, moves in and binds to alpha-phosphate when the pyrophosphoryl transfer is about to occur. The dynamic roles of R82 and R92 are further elucidated by five more crystal structures of two mutant proteins, R82A and R92A, with and without bound ligands. Two oxidized forms of HP are observed with an occupancy ratio of 0.50:0.50 in the 0.89-A structure. The oxidation of HP has significant impact on its binding to the protein as well as the conformation of nearby residue W89. | ||
==About this Structure== | ==About this Structure== | ||
1KBR 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 CL as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/2-amino-4-hydroxy-6-hydroxymethyldihydropteridine_diphosphokinase 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.6.3 2.7.6.3] Full crystallographic information is available from [http:// | 1KBR 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=CL:'>CL</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/2-amino-4-hydroxy-6-hydroxymethyldihydropteridine_diphosphokinase 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.7.6.3 2.7.6.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1KBR OCA]. | ||
==Reference== | ==Reference== | ||
| Line 28: | Line 28: | ||
[[Category: x-ray crystallography]] | [[Category: x-ray crystallography]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:32:17 2008'' | ||
Revision as of 14:32, 21 February 2008
|
CRYSTAL STRUCTURE OF UNLIGATED HPPK(R92A) FROM E.COLI AT 1.55 ANGSTROM RESOLUTION
OverviewOverview
6-Hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) catalyzes the pyrophosphoryl transfer from ATP to 6-hydroxymethyl-7,8-dihydropterin (HP), the first reaction in the folate biosynthetic pathway. Arginine residues 82 and 92, strictly conserved in 35 HPPK sequences, play dynamic roles in the catalytic cycle of the enzyme. At 0.89-A resolution, two distinct conformations are observed for each of the two residues in the crystal structure of the wild-type HPPK in complex with two HP variants, two Mg(2+) ions, and an ATP analogue. Structural information suggests that R92 first binds to the alpha-phosphate group of ATP and then shifts to interact with the beta-phosphate as R82, which initially does not bind to ATP, moves in and binds to alpha-phosphate when the pyrophosphoryl transfer is about to occur. The dynamic roles of R82 and R92 are further elucidated by five more crystal structures of two mutant proteins, R82A and R92A, with and without bound ligands. Two oxidized forms of HP are observed with an occupancy ratio of 0.50:0.50 in the 0.89-A structure. The oxidation of HP has significant impact on its binding to the protein as well as the conformation of nearby residue W89.
About this StructureAbout this Structure
1KBR is a Single protein structure of sequence from Escherichia coli with as ligand. Active as 2-amino-4-hydroxy-6-hydroxymethyldihydropteridine diphosphokinase, with EC number 2.7.6.3 Full crystallographic information is available from OCA.
ReferenceReference
Dynamic roles of arginine residues 82 and 92 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase: crystallographic studies., Blaszczyk J, Li Y, Shi G, Yan H, Ji X, Biochemistry. 2003 Feb 18;42(6):1573-80. PMID:12578370
Page seeded by OCA on Thu Feb 21 13:32:17 2008