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PMID:24069347
| Citation |
Xu, Z, Li, S, Li, J, Li, Y, Feng, X, Wang, R, Xu, H and Zhou, J (2013) The Structural Basis of Erwinia rhapontici Isomaltulose Synthase. PLoS ONE 8:e74788 |
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| Abstract |
Sucrose isomerase NX-5 from Erwiniarhapontici efficiently catalyzes the isomerization of sucrose to isomaltulose (main product) and trehalulose (by-product). To investigate the molecular mechanism controlling sucrose isomer formation, we determined the crystal structures of native NX-5 and its mutant complexes E295Q/sucrose and D241A/glucose at 1.70 Å, 1.70 Å and 2.00 Å, respectively. The overall structure and active site architecture of NX-5 resemble those of other reported sucrose isomerases. Strikingly, the substrate binding mode of NX-5 is also similar to that of trehalulose synthase from Pseudomonasmesoacidophila MX-45 (MutB). Detailed structural analysis revealed the catalytic RXDRX motif and the adjacent 10-residue loop of NX-5 and isomaltulose synthase PalI from Klebsiella sp. LX3 adopt a distinct orientation from those of trehalulose synthases. Mutations of the loop region of NX-5 resulted in significant changes of the product ratio between isomaltulose and trehalulose. The molecular dynamics simulation data supported the product specificity of NX-5 towards isomaltulose and the role of the loop(330-339) in NX-5 catalysis. This work should prove useful for the engineering of sucrose isomerase for industrial carbohydrate biotransformations. |
| Links |
PubMed Online version:10.1371/journal.pone.0074788 |
| Keywords |
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| edit table |
Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0016853: isomerase activity |
ECO:0000314: |
F |
Figure 2. Shows the crystal structure of native NX-5. |
complete | ||||
| GO:0016853: isomerase activity |
ECO:0000315: |
F |
Table 2. Shows the ratios of isomerization products of NX-5 and mutants used to elucidate the product specificity role of the 10 residue loop adjacent to the catalytic site. |
complete | ||||
|
enables |
GO:0016853: isomerase activity |
ECO:0000315: mutant phenotype evidence used in manual assertion |
F |
Seeded From UniProt |
complete | |||
See also
References
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