2e0x
From Proteopedia
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[[Image:2e0x.gif|left|200px]] | [[Image:2e0x.gif|left|200px]] | ||
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| - | | | + | {{STRUCTURE_2e0x| PDB=2e0x | SCENE= }} |
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'''Crystal Structure of Gamma-glutamyltranspeptidase from Escherichia coli (monoclinic form)''' | '''Crystal Structure of Gamma-glutamyltranspeptidase from Escherichia coli (monoclinic form)''' | ||
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==Overview== | ==Overview== | ||
| - | Gamma-glutamyltranspeptidase (GGT) is | + | Gamma-glutamyltranspeptidase (GGT) is an extracellular enzyme that plays a key role in glutathione metabolism. The mature GGT is a heterodimer consisting of L- and S-subunits that is generated by posttranslational cleavage of the peptide bond between Gln-390 and Thr-391 in the precursor protein. Thr-391, which becomes the N-terminal residue of the S-subunit, acts as the active residue in the catalytic reaction. The crystal structure of a mutant GGT, T391A, that is unable to undergo autocatalytic processing, has been determined at 2.55-A resolution. Structural comparison of the precursor protein and mature GGT demonstrates that the structures of the core regions in the two proteins are unchanged, but marked differences are found near the active site. In particular, in the precursor, the segment corresponding to the C-terminal region of the L-subunit occupies the site where the loop (residues 438-449) forms the lid of the gamma-glutamyl group-binding pocket in the mature GGT. This result demonstrates that, upon cleavage of the N-terminal peptide bond of Thr-391, the newly produced C terminus (residues 375-390) flips out, allowing the 438-449 segment to form the gamma-glutamyl group-binding pocket. The electron density map for the T391A protein also identified a water molecule near the carbonyl carbon atom of Gln-390. The spatial arrangement around the water and Thr-391 relative to the scissile peptide bond appears suitable for the initiation of autocatalytic processing, as in other members of the N-terminal nucleophile hydrolase superfamily. |
==About this Structure== | ==About this Structure== | ||
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==Reference== | ==Reference== | ||
| - | Crystal | + | Crystal structure of the gamma-glutamyltranspeptidase precursor protein from Escherichia coli. Structural changes upon autocatalytic processing and implications for the maturation mechanism., Okada T, Suzuki H, Wada K, Kumagai H, Fukuyama K, J Biol Chem. 2007 Jan 26;282(4):2433-9. Epub 2006 Nov 29. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/17135273 17135273] |
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Gamma-glutamyltransferase]] | [[Category: Gamma-glutamyltransferase]] | ||
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[[Category: Okada, T.]] | [[Category: Okada, T.]] | ||
[[Category: Wada, K.]] | [[Category: Wada, K.]] | ||
| - | [[Category: | + | [[Category: Gamma-glutamyltransferase]] |
| - | [[Category: | + | [[Category: Gamma-gtp]] |
| - | [[Category: | + | [[Category: Ggt]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Apr 9 14:38:58 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 11:39, 9 April 2008
Crystal Structure of Gamma-glutamyltranspeptidase from Escherichia coli (monoclinic form)
Overview
Gamma-glutamyltranspeptidase (GGT) is an extracellular enzyme that plays a key role in glutathione metabolism. The mature GGT is a heterodimer consisting of L- and S-subunits that is generated by posttranslational cleavage of the peptide bond between Gln-390 and Thr-391 in the precursor protein. Thr-391, which becomes the N-terminal residue of the S-subunit, acts as the active residue in the catalytic reaction. The crystal structure of a mutant GGT, T391A, that is unable to undergo autocatalytic processing, has been determined at 2.55-A resolution. Structural comparison of the precursor protein and mature GGT demonstrates that the structures of the core regions in the two proteins are unchanged, but marked differences are found near the active site. In particular, in the precursor, the segment corresponding to the C-terminal region of the L-subunit occupies the site where the loop (residues 438-449) forms the lid of the gamma-glutamyl group-binding pocket in the mature GGT. This result demonstrates that, upon cleavage of the N-terminal peptide bond of Thr-391, the newly produced C terminus (residues 375-390) flips out, allowing the 438-449 segment to form the gamma-glutamyl group-binding pocket. The electron density map for the T391A protein also identified a water molecule near the carbonyl carbon atom of Gln-390. The spatial arrangement around the water and Thr-391 relative to the scissile peptide bond appears suitable for the initiation of autocatalytic processing, as in other members of the N-terminal nucleophile hydrolase superfamily.
About this Structure
2E0X is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure of the gamma-glutamyltranspeptidase precursor protein from Escherichia coli. Structural changes upon autocatalytic processing and implications for the maturation mechanism., Okada T, Suzuki H, Wada K, Kumagai H, Fukuyama K, J Biol Chem. 2007 Jan 26;282(4):2433-9. Epub 2006 Nov 29. PMID:17135273 Page seeded by OCA on Wed Apr 9 14:38:58 2008
