2hcz

Crystal structure of EXPB1 (Zea m 1), a beta-expansin and group-1 pollen allergen from maize

spinqualitylabelsall models 2hcz, resolution 2.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2hcz is a 1 chain structure with sequence from Zea mays. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.75Å Ligands: FCA, HYP, MAN, NAG, XYS Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function EXPB1_MAIZE May aid fertilization by loosening the cell wall of the stigma and style, thereby facilitating penetration of the pollen tube. Acts selectively on grass cell walls, which are relatively poor in pectins and xyloglucans and rich in glucuronoarabinoxylans and (1-3),(1-4)-beta-D-glucans, when compared with cell walls of other angiosperms, including other monocots. 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 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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