2hcz
From Proteopedia
(New page: 200px<br /><applet load="2hcz" size="450" color="white" frame="true" align="right" spinBox="true" caption="2hcz, resolution 2.750Å" /> '''Crystal structure o...) |
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| - | [[Image:2hcz.gif|left|200px]]<br /><applet load="2hcz" size=" | + | [[Image:2hcz.gif|left|200px]]<br /><applet load="2hcz" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2hcz, resolution 2.750Å" /> | caption="2hcz, resolution 2.750Å" /> | ||
'''Crystal structure of EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize'''<br /> | '''Crystal structure of EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Expansins are small extracellular proteins that promote turgor-driven | + | Expansins are small extracellular proteins that promote turgor-driven extension of plant cell walls. EXPB1 (also called Zea m 1) is a member of the beta-expansin subfamily known in the allergen literature as group-1 grass pollen allergens. EXPB1 induces extension and stress relaxation of grass cell walls. To help elucidate expansin's mechanism of wall loosening, we determined the structure of EXPB1 by x-ray crystallography to 2.75-A resolution. EXPB1 consists of two domains closely packed and aligned so as to form a long, shallow groove with potential to bind a glycan backbone of approximately 10 sugar residues. The structure of EXPB1 domain 1 resembles that of family-45 glycoside hydrolase (GH45), with conservation of most of the residues in the catalytic site. However, EXPB1 lacks a second aspartate that serves as the catalytic base required for hydrolytic activity in GH45 enzymes. Domain 2 of EXPB1 is an Ig-like beta-sandwich, with aromatic and polar residues that form a potential surface for polysaccharide binding in line with the glycan binding cleft of domain 1. EXPB1 binds to maize cell walls, most strongly to xylans, causing swelling of the cell wall. Tests for hydrolytic activity by EXPB1 with various wall polysaccharides proved negative. Moreover, GH45 enzymes and a GH45-related protein called "swollenin" lacked wall extension activity comparable to that of expansins. We propose a model of expansin action in which EXPB1 facilitates the local movement and stress relaxation of arabinoxylan-cellulose networks within the wall by noncovalent rearrangement of its target. |
==About this Structure== | ==About this Structure== | ||
| - | 2HCZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zea_mays Zea mays] with MAN and FCA as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 2HCZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Zea_mays Zea mays] with <scene name='pdbligand=MAN:'>MAN</scene> and <scene name='pdbligand=FCA:'>FCA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HCZ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Zea mays]] | [[Category: Zea mays]] | ||
| - | [[Category: Cosgrove, D | + | [[Category: Cosgrove, D J.]] |
| - | [[Category: Yennawar, N | + | [[Category: Yennawar, N H.]] |
[[Category: FCA]] | [[Category: FCA]] | ||
[[Category: MAN]] | [[Category: MAN]] | ||
[[Category: domain 1 is a beta barrel and domain 2 is a immunoglobulin like beta-sandwich]] | [[Category: domain 1 is a beta barrel and domain 2 is a immunoglobulin like beta-sandwich]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:40:38 2008'' |
Revision as of 15:40, 21 February 2008
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Crystal structure of EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize
Overview
Expansins are small extracellular proteins that promote turgor-driven extension of plant cell walls. EXPB1 (also called Zea m 1) is a member of the beta-expansin subfamily known in the allergen literature as group-1 grass pollen allergens. EXPB1 induces extension and stress relaxation of grass cell walls. To help elucidate expansin's mechanism of wall loosening, we determined the structure of EXPB1 by x-ray crystallography to 2.75-A resolution. EXPB1 consists of two domains closely packed and aligned so as to form a long, shallow groove with potential to bind a glycan backbone of approximately 10 sugar residues. The structure of EXPB1 domain 1 resembles that of family-45 glycoside hydrolase (GH45), with conservation of most of the residues in the catalytic site. However, EXPB1 lacks a second aspartate that serves as the catalytic base required for hydrolytic activity in GH45 enzymes. Domain 2 of EXPB1 is an Ig-like beta-sandwich, with aromatic and polar residues that form a potential surface for polysaccharide binding in line with the glycan binding cleft of domain 1. EXPB1 binds to maize cell walls, most strongly to xylans, causing swelling of the cell wall. Tests for hydrolytic activity by EXPB1 with various wall polysaccharides proved negative. Moreover, GH45 enzymes and a GH45-related protein called "swollenin" lacked wall extension activity comparable to that of expansins. We propose a model of expansin action in which EXPB1 facilitates the local movement and stress relaxation of arabinoxylan-cellulose networks within the wall by noncovalent rearrangement of its target.
About this Structure
2HCZ is a Single protein structure of sequence from Zea mays with and as ligands. Full crystallographic information is available from OCA.
Reference
Crystal structure and activities of EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize., Yennawar NH, Li LC, Dudzinski DM, Tabuchi A, Cosgrove DJ, Proc Natl Acad Sci U S A. 2006 Oct 3;103(40):14664-71. Epub 2006 Sep 19. PMID:16984999
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