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| {{STRUCTURE_2b1k| PDB=2b1k | SCENE= }} | | {{STRUCTURE_2b1k| PDB=2b1k | SCENE= }} |
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| '''Crystal structure of E. coli CcmG protein'''
| | ===Crystal structure of E. coli CcmG protein=== |
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| ==Overview==
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| CcmG, also designated DsbE, functions as a periplasmic protein thiol:disulfide oxidoreductase and is required for cytochrome c maturation. Here we report the crystal structures of Escherichia coli CcmG and its two mutants, P144A and the N-terminal fifty seven-residue deletion mutant, and two additional deletion mutants were studied by circular dichroism. Structural comparison of E. coli CcmG with its deletion mutants reveals that the N-terminal beta-sheet is essential for maintaining the folding topology and consequently maintaining the active-site structure of CcmG. Pro144 and Glu145 are key residues of the fingerprint region of CcmG. Pro144 is in cis-configuration, and it makes van der Waals interactions with the active-site disulfide Cys80-Cys83 and forms a C--H...O hydrogen bond with Thr82, helping stabilize the active-site structure. Glu145 forms a salt-bridge and hydrogen-bond network with other residues of the fingerprint region and with Arg158, further stabilizing the active-site structure. The cis-configuration of Pro144 makes the backbone nitrogen and oxygen of Ala143 exposed to solvent, favorable for interacting with binding partners. The key role of cis-Pro144 is verified by the P144A mutant, which contains trans-Ala144 and displays redox property changes. Structural comparison of E. coli CcmG with the recently reported structure of CcmG in complex with the N-terminal domain of DsbD reveals that Tyr141 undergoes conformational changes upon binding DsbD. A cis-proline located at the N-terminus of the first beta-strand of the betabetaalpha motif of the thioredoxin-like domain is a conserved structural feature of the thioredoxin superfamily.
| | The line below this paragraph, {{ABSTRACT_PUBMED_17019698}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 17019698 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_17019698}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Fingerprint rigion]] | | [[Category: Fingerprint rigion]] |
| [[Category: N-terminal beta-sheet]] | | [[Category: N-terminal beta-sheet]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 19:44:22 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 12:46:53 2008'' |