3HU7

Structural characterization and binding studies of a plant pathogenesis related protein heamanthin from haemanthus multiflorus reveal its dual inhibitory effects against xylanase and alpha-amylase

Summary for 3HU7

• Entry DOI: 10.2210/pdb3hu7/pdb
• Related: 1OM0 2HVM 3D5H
• Descriptor: Haementhin, ACETATE ION, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: plant pathogenesis related protein, inhibitor, tim barrel, protein binding
• Biological source: Scadoxus multiflorus
• Total number of polymer chains: 1
• Total formula weight: 29972.40

Authors

Kumar, S.,Singh, N.,Sinha, M.,Bhushan, A.,Kaur, P.,Srinivasan, A.,Sharma, S.,Singh, T.P. (deposition date: 2009-06-13, release date: 2010-04-28, Last modification date: 2024-11-20)

Primary citation

Kumar, S.,Singh, N.,Sinha, M.,Dube, D.,Singh, S.B.,Bhushan, A.,Kaur, P.,Srinivasan, A.,Sharma, S.,Singh, T.P.
Crystal structure determination and inhibition studies of a novel xylanase and alpha-amylase inhibitor protein (XAIP) from Scadoxus multiflorus.
Febs J., 277:2868-2882, 2010

PubMed Abstract: A novel plant protein isolated from the underground bulbs of Scadoxus multiflorus, xylanase and alpha-amylase inhibitor protein (XAIP), inhibits two structurally and functionally unrelated enzymes: xylanase and alpha-amylase. The mature protein contains 272 amino acid residues which show sequence identities of 48% to the plant chitinase hevamine and 36% to xylanase inhibitor protein-I, a double-headed inhibitor of GH10 and GH11 xylanases. However, unlike hevamine, it is enzymatically inactive and, unlike xylanase inhibitor protein-I, it inhibits two functionally different classes of enzyme. The crystal structure of XAIP has been determined at 2.0 A resolution and refined to R(cryst) and R(free) factors of 15.2% and 18.6%, respectively. The polypeptide chain of XAIP adopts a modified triosephosphate isomerase barrel fold with eight beta-strands in the inner circle and nine alpha-helices forming the outer ring. The structure contains three cis peptide bonds: Gly33-Phe34, Tyr159-Pro160 and Trp253-Asp254. Although hevamine has a long accessible carbohydrate-binding channel, in XAIP this channel is almost completely filled with the side-chains of residues Phe13, Pro77, Lys78 and Trp253. Solution studies indicate that XAIP inhibits GH11 family xylanases and GH13 family alpha-amylases through two independent binding sites located on opposite surfaces of the protein. Comparison of the structure of XAIP with that of xylanase inhibitor protein-I, and docking studies, suggest that loops alpha3-beta4 and alpha4-beta5 may be involved in the binding of GH11 xylanase, and that helix alpha7 and loop beta6-alpha6 are suitable for the interaction with alpha-amylase.

PubMed: 20528916
DOI: 10.1111/j.1742-4658.2010.07703.x

Experimental method

X-RAY DIFFRACTION (2 Å)