1wm9: Difference between revisions

Revision as of 16:45, 21 February 2008

Structure of GTP cyclohydrolase I from Thermus thermophilus HB8

OverviewOverview

GTP cyclohydrolase I (GTPCH1) catalyzes the conversion of GTP to dihydroneopterin 3'-triphosphate. We found that an 8-oxoguanine derivative of GTP (8-oxo-GTP) strongly bound to GTPCH1 from Thermus thermophilus HB8 (tGTPCH1) as a competitive inhibitor. The affinity of 8-oxo-GTP was three orders of magnitude greater than that of GTP. These results suggest that 8-oxo-GTP is a transition state analogue of GTPCH1. We have solved the X-ray crystal structures of tGTPCH1 complexed with 8-oxo-GTP and 8-oxo-dGTP at 2.0 and 1.8 A resolution, respectively, as well as the free form of the enzyme at 2.2 A resolution. In the structure of tGTPCH1 complexed with 8-oxo-GTP or 8-oxo-dGTP, the oxygen atoms at O8 of the 8-oxoguanine groups, together with residues Cys108, His111 and Cys179, are coordinated to the zinc ion. The water molecule between Ndelta1 of His177 and N7 of 8-oxoguanine is conserved in both structures. These structural data are in accordance with one of the proposed transition states. Superimpositioning of the structures indicates the imidazole ring of His110 is rotated, implying concomitant proton transfer to the ribose ring O4'. Based on these structural data we propose a novel reaction mechanism for GTPCH1.

About this StructureAbout this Structure

1WM9 is a Single protein structure of sequence from Thermus thermophilus with as ligand. Active as GTP cyclohydrolase I, with EC number 3.5.4.16 Full crystallographic information is available from OCA.

ReferenceReference

Novel reaction mechanism of GTP cyclohydrolase I. High-resolution X-ray crystallography of Thermus thermophilus HB8 enzyme complexed with a transition state analogue, the 8-oxoguanine derivative., Tanaka Y, Nakagawa N, Kuramitsu S, Yokoyama S, Masui R, J Biochem. 2005 Sep;138(3):263-75. PMID:16169877

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-[[Image:1wm9.gif|left|200px]]<br /><applet load="1wm9" size="450" color="white" frame="true" align="right" spinBox="true"
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 caption="1wm9, resolution 2.2&Aring;" />
 '''Structure of GTP cyclohydrolase I from Thermus thermophilus HB8'''<br />
 ==Overview==
-GTP cyclohydrolase I (GTPCH1) catalyzes the conversion of GTP to, dihydroneopterin 3'-triphosphate. We found that an 8-oxoguanine derivative, of GTP (8-oxo-GTP) strongly bound to GTPCH1 from Thermus thermophilus HB8, (tGTPCH1) as a competitive inhibitor. The affinity of 8-oxo-GTP was three, orders of magnitude greater than that of GTP. These results suggest that, 8-oxo-GTP is a transition state analogue of GTPCH1. We have solved the, X-ray crystal structures of tGTPCH1 complexed with 8-oxo-GTP and, 8-oxo-dGTP at 2.0 and 1.8 A resolution, respectively, as well as the free, form of the enzyme at 2.2 A resolution. In the structure of tGTPCH1, complexed with 8-oxo-GTP or 8-oxo-dGTP, the oxygen atoms at O8 of the, 8-oxoguanine groups, together with residues Cys108, His111 and Cys179, are, coordinated to the zinc ion. The water molecule between Ndelta1 of His177, and N7 of 8-oxoguanine is conserved in both structures. These structural, data are in accordance with one of the proposed transition states., Superimpositioning of the structures indicates the imidazole ring of, His110 is rotated, implying concomitant proton transfer to the ribose ring, O4'. Based on these structural data we propose a novel reaction mechanism, for GTPCH1.
+GTP cyclohydrolase I (GTPCH1) catalyzes the conversion of GTP to dihydroneopterin 3'-triphosphate. We found that an 8-oxoguanine derivative of GTP (8-oxo-GTP) strongly bound to GTPCH1 from Thermus thermophilus HB8 (tGTPCH1) as a competitive inhibitor. The affinity of 8-oxo-GTP was three orders of magnitude greater than that of GTP. These results suggest that 8-oxo-GTP is a transition state analogue of GTPCH1. We have solved the X-ray crystal structures of tGTPCH1 complexed with 8-oxo-GTP and 8-oxo-dGTP at 2.0 and 1.8 A resolution, respectively, as well as the free form of the enzyme at 2.2 A resolution. In the structure of tGTPCH1 complexed with 8-oxo-GTP or 8-oxo-dGTP, the oxygen atoms at O8 of the 8-oxoguanine groups, together with residues Cys108, His111 and Cys179, are coordinated to the zinc ion. The water molecule between Ndelta1 of His177 and N7 of 8-oxoguanine is conserved in both structures. These structural data are in accordance with one of the proposed transition states. Superimpositioning of the structures indicates the imidazole ring of His110 is rotated, implying concomitant proton transfer to the ribose ring O4'. Based on these structural data we propose a novel reaction mechanism for GTPCH1.
 ==About this Structure==
-WM9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/GTP_cyclohydrolase_I GTP cyclohydrolase I], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.4.16 3.5.4.16] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1WM9 OCA].
+WM9 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermus_thermophilus Thermus thermophilus] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/GTP_cyclohydrolase_I GTP cyclohydrolase I], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.5.4.16 3.5.4.16] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WM9 OCA].
 ==Reference==
-Novel reaction mechanism of GTP cyclohydrolase I. High-resolution X-ray crystallography of Thermus thermophilus HB8 enzyme complexed with a transition state analogue, the 8-oxoguanine derivative., Tanaka Y, Nakagawa N, Kuramitsu S, Yokoyama S, Masui R, J Biochem (Tokyo). 2005 Sep;138(3):263-75. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16169877 16169877]
+Novel reaction mechanism of GTP cyclohydrolase I. High-resolution X-ray crystallography of Thermus thermophilus HB8 enzyme complexed with a transition state analogue, the 8-oxoguanine derivative., Tanaka Y, Nakagawa N, Kuramitsu S, Yokoyama S, Masui R, J Biochem. 2005 Sep;138(3):263-75. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=16169877 16169877]
 [[Category: GTP cyclohydrolase I]]
 [[Category: Single protein]]
 [[Category: Thermus thermophilus]]
-[[Category: RSGI, RIKEN.Structural.Genomics/Proteomics.Initiative.]]
+[[Category: RSGI, RIKEN Structural Genomics/Proteomics Initiative.]]
 [[Category: Tanaka, Y.]]
 [[Category: ZN]]
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 [[Category: tetrahydrobiopterin]]
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