1x19
From Proteopedia
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| - | [[Image:1x19.gif|left|200px]] | + | [[Image:1x19.gif|left|200px]] |
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| - | '''Crystal structure of BchU involved in bacteriochlorophyll c biosynthesis''' | + | {{Structure |
| + | |PDB= 1x19 |SIZE=350|CAPTION= <scene name='initialview01'>1x19</scene>, resolution 2.27Å | ||
| + | |SITE= | ||
| + | |LIGAND= <scene name='pdbligand=SO4:SULFATE ION'>SO4</scene> | ||
| + | |ACTIVITY= | ||
| + | |GENE= | ||
| + | }} | ||
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| + | '''Crystal structure of BchU involved in bacteriochlorophyll c biosynthesis''' | ||
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==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1X19 is a [ | + | 1X19 is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Chlorobaculum_tepidum Chlorobaculum tepidum]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1X19 OCA]. |
==Reference== | ==Reference== | ||
| - | Crystal structures of BchU, a methyltransferase involved in bacteriochlorophyll c biosynthesis, and its complex with S-adenosylhomocysteine: implications for reaction mechanism., Wada K, Yamaguchi H, Harada J, Niimi K, Osumi S, Saga Y, Oh-Oka H, Tamiaki H, Fukuyama K, J Mol Biol. 2006 Jul 21;360(4):839-49. Epub 2006 Jun 8. PMID:[http:// | + | Crystal structures of BchU, a methyltransferase involved in bacteriochlorophyll c biosynthesis, and its complex with S-adenosylhomocysteine: implications for reaction mechanism., Wada K, Yamaguchi H, Harada J, Niimi K, Osumi S, Saga Y, Oh-Oka H, Tamiaki H, Fukuyama K, J Mol Biol. 2006 Jul 21;360(4):839-49. Epub 2006 Jun 8. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/16797589 16797589] |
[[Category: Chlorobaculum tepidum]] | [[Category: Chlorobaculum tepidum]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: sam]] | [[Category: sam]] | ||
| - | ''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 15:03:57 2008'' |
Revision as of 13:03, 20 March 2008
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal structure of BchU involved in bacteriochlorophyll c biosynthesis
Overview
BchU plays a role in bacteriochlorophyll c biosynthesis by catalyzing methylation at the C-20 position of cyclic tetrapyrrole chlorin using S-adenosylmethionine (SAM) as a methyl source. This methylation causes red-shifts of the electronic absorption spectrum of the light-harvesting pigment, allowing green photosynthetic bacteria to adapt to low-light environments. We have determined the crystal structures of BchU and its complex with S-adenosylhomocysteine (SAH). BchU forms a dimer and each subunit consists of two domains, an N-terminal domain and a C-terminal domain. Dimerization occurs through interactions between the N-terminal domains and the residues responsible for the catalytic reaction are in the C-terminal domain. The binding site of SAH is located in a large cavity between the two domains, where SAH is specifically recognized by many hydrogen bonds and a salt-bridge. The electron density map of BchU in complex with an analog of bacteriochlorophyll c located its central metal near the SAH-binding site, but the tetrapyrrole ring was invisible, suggesting that binding of the ring to BchU is loose and/or occupancy of the ring is low. It is likely that His290 acts as a ligand for the central metal of the substrate. The orientation of the substrate was predicted by simulation, and allows us to propose a mechanism for the BchU directed methylation: the strictly conserved Tyr246 residue acts catalytically in the direct transfer of the methyl group from SAM to the substrate through an S(N)2-like mechanism.
About this Structure
1X19 is a Single protein structure of sequence from Chlorobaculum tepidum. Full crystallographic information is available from OCA.
Reference
Crystal structures of BchU, a methyltransferase involved in bacteriochlorophyll c biosynthesis, and its complex with S-adenosylhomocysteine: implications for reaction mechanism., Wada K, Yamaguchi H, Harada J, Niimi K, Osumi S, Saga Y, Oh-Oka H, Tamiaki H, Fukuyama K, J Mol Biol. 2006 Jul 21;360(4):839-49. Epub 2006 Jun 8. PMID:16797589
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