1ktw
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1ktw.gif|left|200px]] | [[Image:1ktw.gif|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1ktw", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | + | or leave the SCENE parameter empty for the default display. | |
| - | | | + | --> |
| - | | | + | {{STRUCTURE_1ktw| PDB=1ktw | SCENE= }} |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''IOTA-CARRAGEENASE COMPLEXED TO IOTA-CARRAGEENAN FRAGMENTS''' | '''IOTA-CARRAGEENASE COMPLEXED TO IOTA-CARRAGEENAN FRAGMENTS''' | ||
| Line 29: | Line 26: | ||
[[Category: Kahn, R.]] | [[Category: Kahn, R.]] | ||
[[Category: Michel, G.]] | [[Category: Michel, G.]] | ||
| - | [[Category: | + | [[Category: Hydrolase]] |
| - | [[Category: | + | [[Category: Iota-carrageenan double helix degradation]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 23:10:05 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 20:10, 2 May 2008
IOTA-CARRAGEENASE COMPLEXED TO IOTA-CARRAGEENAN FRAGMENTS
Overview
iota-Carrageenans are sulfated 1,3-alpha-1,4-beta-galactans from the cell walls of red algae, which auto-associate into crystalline fibers made of aggregates of double-stranded helices. iota-Carrageenases, which constitute family 82 of glycoside hydrolases, fold into a right-handed beta-helix. Here, the structure of Alteromonas fortis iota-carrageenase bound to iota-carrageenan fragments was solved at 2.0A resolution (PDB 1KTW). The enzyme holds a iota-carrageenan tetrasaccharide (subsites +1 to +4) and a disaccharide (subsites -3, -4), thus providing the first direct determination of a 3D structure of iota-carrageenan. Electrostatic interactions between basic protein residues and the sulfate substituents of the polysaccharide chain dominate iota-carrageenan recognition. Glu245 and Asp247 are the proton donor and the base catalyst, respectively. C-terminal domain A, which was highly flexible in the native enzyme structure, adopts a alpha/beta-fold, also found in DNA/RNA-binding domains. In the substrate-enzyme complex, this polyanion-binding module shifts toward the beta-helix groove, forming a tunnel. Thus, from an open conformation which allows for the initial endo-attack of iota-carrageenan chains, the enzyme switches to a closed-tunnel form, consistent with its highly processive character, as seen from the electron-microscopy analysis of the degradation of iota-carrageenan fibers.
About this Structure
1KTW is a Single protein structure of sequence from Alteromonas sp. atcc 43554. Full crystallographic information is available from OCA.
Reference
The structural bases of the processive degradation of iota-carrageenan, a main cell wall polysaccharide of red algae., Michel G, Helbert W, Kahn R, Dideberg O, Kloareg B, J Mol Biol. 2003 Nov 28;334(3):421-33. PMID:14623184 Page seeded by OCA on Fri May 2 23:10:05 2008
