1NU5

Crystal structure of Pseudomonas sp. P51 Chloromuconate lactonizing enzyme

Summary for 1NU5

• Entry DOI: 10.2210/pdb1nu5/pdb
• Descriptor: Chloromuconate cycloisomerase, MANGANESE (II) ION (3 entities in total)
• Functional Keywords: enzyme, muconate, dehalogenation, isomerase
• Biological source: Pseudomonas sp.
• Total number of polymer chains: 1
• Total formula weight: 39641.84

Authors

Kajander, T.,Lehtio, L.,Goldman, A. (deposition date: 2003-01-31, release date: 2003-12-30, Last modification date: 2024-03-13)

Primary citation

Kajander, T.,Lehtio, L.,Schlomann, M.,Goldman, A.
The structure of Pseudomonas P51 Cl-muconate lactonizing enzyme: co-evolution of structure and dynamics with the dehalogenation function.
Protein Sci., 12:1855-1864, 2003

PubMed Abstract: 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.

PubMed: 12930985
DOI: 10.1110/ps.0388503

Experimental method

X-RAY DIFFRACTION (1.95 Å)