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| {{STRUCTURE_1nu5| PDB=1nu5 | SCENE= }} | | {{STRUCTURE_1nu5| PDB=1nu5 | SCENE= }} |
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| '''Crystal structure of Pseudomonas sp. P51 Chloromuconate lactonizing enzyme'''
| | ===Crystal structure of Pseudomonas sp. P51 Chloromuconate lactonizing enzyme=== |
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| ==Overview==
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| Bacterial muconate lactonizing enzymes (MLEs) catalyze the conversion of cis,cis-muconate as a part of the beta-ketoadipate pathway, and some MLEs are also able to dehalogenate chlorinated muconates (Cl-MLEs). The basis for the Cl-MLEs dehalogenating activity is still unclear. To further elucidate the differences between MLEs and Cl-MLEs, we have solved the structure of Pseudomonas P51 Cl-MLE at 1.95 A resolution. Comparison of Pseudomonas MLE and Cl-MLE structures reveals the presence of a large cavity in the Cl-MLEs. The cavity may be related to conformational changes on substrate binding in Cl-MLEs, at Gly52. Site-directed mutagenesis on Pseudomonas MLE core positions to the equivalent Cl-MLE residues showed that the variant Thr52Gly was rather inactive, whereas the Thr52Gly-Phe103Ser variant had regained part of the activity. These residues form a hydrogen bond in the Cl-MLEs. The Cl-MLE structure, as a result of the Thr-to-Gly change, is more flexible than MLE: As a mobile loop closes over the active site, a conformational change at Gly52 is observed in Cl-MLEs. The loose packing and structural motions in Cl-MLE may be required for the rotation of the lactone ring in the active site necessary for the dehalogenating activity of Cl-MLEs. Furthermore, we also suggest that differences in the active site mobile loop sequence between MLEs and Cl-MLEs result in lower active site polarity in Cl-MLEs, possibly affecting catalysis. These changes could result in slower product release from Cl-MLEs and make it a better enzyme for dehalogenation of substrate.
| | The line below this paragraph, {{ABSTRACT_PUBMED_12930985}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 12930985 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_12930985}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Enzyme]] | | [[Category: Enzyme]] |
| [[Category: Muconate]] | | [[Category: Muconate]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 02:58:54 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 08:02:35 2008'' |
