| Structural highlights
2xqr is a 12 chain structure with sequence from Arabidopsis thaliana and Nicotiana tabacum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , , , , , |
| Related: | 2cj7, 2cj5, 2cj4, 1rj1, 1rj4, 2cj8, 2cj6 |
| Activity: | Beta-fructofuranosidase, with EC number 3.2.1.26 |
| Resources: | FirstGlance, OCA, RCSB, PDBsum |
Function
[INV1_ARATH] Beta-fructofuranosidase that can use sucrose and 1-kestose, and, to a lower extent, neokestose and levan, as substrates, but not inuline.[1] [2]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Invertases are highly regulated enzymes with essential functions in carbohydrate partitioning, sugar signaling, and plant development. Here we present the 2.6 A crystal structure of Arabidopsis cell-wall invertase 1 (INV1) in complex with a protein inhibitor (CIF, or cell-wall inhibitor of beta-fructosidase) from tobacco. The structure identifies a small amino acid motif in CIF that directly targets the invertase active site. The activity of INV1 and its interaction with CIF are strictly pH-dependent with a maximum at about pH 4.5. At this pH, isothermal titration calorimetry reveals that CIF tightly binds its target with nanomolar affinity. CIF competes with sucrose (Suc) for the same binding site, suggesting that both the extracellular Suc concentration and the pH changes regulate association of the complex. A conserved glutamate residue in the complex interface was previously identified as an important quantitative trait locus affecting fruit quality, which implicates the invertase-inhibitor complex as a main regulator of carbon partitioning in plants. Comparison of the CIF/INV1 structure with the complex between the structurally CIF-related pectin methylesterase inhibitor (PMEI) and pectin methylesterase indicates a common targeting mechanism in PMEI and CIF. However, CIF and PMEI use distinct surface areas to selectively inhibit very different enzymatic scaffolds.
Structural insights into the pH-controlled targeting of plant cell-wall invertase by a specific inhibitor protein.,Hothorn M, Van den Ende W, Lammens W, Rybin V, Scheffzek K Proc Natl Acad Sci U S A. 2010 Sep 21. PMID:20858733[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Matrai J, Lammens W, Jonckheer A, Le Roy K, Rabijns A, Van den Ende W, De Maeyer M. An alternate sucrose binding mode in the E203Q Arabidopsis invertase mutant: An X-ray crystallography and docking study. Proteins. 2007 Oct 26;. PMID:17963237 doi:10.1002/prot.21700
- ↑ Le Roy K, Lammens W, Verhaest M, De Coninck B, Rabijns A, Van Laere A, Van den Ende W. Unraveling the difference between invertases and fructan exohydrolases: a single amino acid (Asp-239) substitution transforms Arabidopsis cell wall invertase1 into a fructan 1-exohydrolase. Plant Physiol. 2007 Nov;145(3):616-25. Epub 2007 Sep 14. PMID:17873089 doi:pp.107.105049
- ↑ Hothorn M, Van den Ende W, Lammens W, Rybin V, Scheffzek K. Structural insights into the pH-controlled targeting of plant cell-wall invertase by a specific inhibitor protein. Proc Natl Acad Sci U S A. 2010 Sep 21. PMID:20858733 doi:10.1073/pnas.1004481107
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