1wcg
From Proteopedia
| Line 4: | Line 4: | ||
==Overview== | ==Overview== | ||
| - | The aphid Brevicoryne brassicae is a specialist feeding on Brassicaceae | + | The aphid Brevicoryne brassicae is a specialist feeding on Brassicaceae plants. The insect has an intricate defence system involving a beta-D-thioglucosidase (myrosinase) that hydrolyses glucosinolates sequestered from the host plant into volatile isothiocyanates. These isothiocyanates act synergistically with the pheromone E-beta-farnesene to form an alarm system when the aphid is predated. In order to investigate the enzymatic characteristics of the aphid myrosinase and its three-dimensional structure, milligram amounts of pure recombinant aphid myrosinase were obtained from Echerichia coli. The recombinant enzyme had similar physiochemical properties to the native enzyme. The global structure is very similar to Sinapis alba myrosinase and plant beta-O-glucosidases. Aphid myrosinase has two catalytic glutamic acid residues positioned as in plant beta-O-glucosidases, and it is not obvious why this unusual enzyme hydrolyses glucosinolates, the common substrates of plant myrosinases which are normally not hydrolyzed by plant beta-O-glucosidases. The only residue specific for aphid myrosinase in proximity of the glycosidic linkage is Tyr180 which may have a catalytic role. The aglycon binding site differs strongly from plant myrosinase, whereas due to the presence of Trp424 in the glucose binding site, this part of the active site is more similar to plant beta-O-glucosidases, as plant myrosinases carry a phenylalanine residue at this position. |
==About this Structure== | ==About this Structure== | ||
| Line 13: | Line 13: | ||
[[Category: Brevicoryne brassicae]] | [[Category: Brevicoryne brassicae]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Transferred entry: 3 | + | [[Category: Transferred entry: 3 2.1 147]] |
[[Category: Arzt, S.]] | [[Category: Arzt, S.]] | ||
| - | [[Category: Bones, A | + | [[Category: Bones, A M.]] |
[[Category: Brandt, A.]] | [[Category: Brandt, A.]] | ||
| - | [[Category: Burmeister, W | + | [[Category: Burmeister, W P.]] |
| - | [[Category: Haertel, F | + | [[Category: Haertel, F V.]] |
[[Category: Husebye, H.]] | [[Category: Husebye, H.]] | ||
| - | [[Category: Rossiter, J | + | [[Category: Rossiter, J T.]] |
[[Category: GOL]] | [[Category: GOL]] | ||
[[Category: aphid]] | [[Category: aphid]] | ||
| Line 32: | Line 32: | ||
[[Category: thioglucosidase]] | [[Category: thioglucosidase]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:42:50 2008'' |
Revision as of 13:42, 21 February 2008
|
APHID MYROSINASE
Overview
The aphid Brevicoryne brassicae is a specialist feeding on Brassicaceae plants. The insect has an intricate defence system involving a beta-D-thioglucosidase (myrosinase) that hydrolyses glucosinolates sequestered from the host plant into volatile isothiocyanates. These isothiocyanates act synergistically with the pheromone E-beta-farnesene to form an alarm system when the aphid is predated. In order to investigate the enzymatic characteristics of the aphid myrosinase and its three-dimensional structure, milligram amounts of pure recombinant aphid myrosinase were obtained from Echerichia coli. The recombinant enzyme had similar physiochemical properties to the native enzyme. The global structure is very similar to Sinapis alba myrosinase and plant beta-O-glucosidases. Aphid myrosinase has two catalytic glutamic acid residues positioned as in plant beta-O-glucosidases, and it is not obvious why this unusual enzyme hydrolyses glucosinolates, the common substrates of plant myrosinases which are normally not hydrolyzed by plant beta-O-glucosidases. The only residue specific for aphid myrosinase in proximity of the glycosidic linkage is Tyr180 which may have a catalytic role. The aglycon binding site differs strongly from plant myrosinase, whereas due to the presence of Trp424 in the glucose binding site, this part of the active site is more similar to plant beta-O-glucosidases, as plant myrosinases carry a phenylalanine residue at this position.
About this Structure
1WCG is a Single protein structure of sequence from Brevicoryne brassicae with as ligand. Active as Transferred entry: 3.2.1.147, with EC number 3.2.3.1 Known structural/functional Site: . Full crystallographic information is available from OCA.
Reference
Crystal structure at 1.1 Angstroms resolution of an insect myrosinase from Brevicoryne brassicae shows its close relationship to beta-glucosidases., Husebye H, Arzt S, Burmeister WP, Hartel FV, Brandt A, Rossiter JT, Bones AM, Insect Biochem Mol Biol. 2005 Dec;35(12):1311-20. Epub 2005 Aug 18. PMID:16291087
Page seeded by OCA on Thu Feb 21 15:42:50 2008
Categories: Brevicoryne brassicae | Single protein | Transferred entry: 3 2.1 147 | Arzt, S. | Bones, A M. | Brandt, A. | Burmeister, W P. | Haertel, F V. | Husebye, H. | Rossiter, J T. | GOL | Aphid | Beta-barrel | Beta-glucosidase | Glucosidase | Glycosidase | Hydrolase | Insect | Myrosinase | Thioglucosidase
