1HJS

Structure of two fungal beta-1,4-galactanases: searching for the basis for temperature and pH optimum.

1HJS の概要

• エントリーDOI: 10.2210/pdb1hjs/pdb
• 関連するPDBエントリー: 1HJQ 1HJU
• 分子名称: BETA-1,4-GALACTANASE, 2-acetamido-2-deoxy-beta-D-glucopyranose, SULFATE ION, ... (6 entities in total)
• 機能のキーワード: beta-1, 4-galactanases, family 53 glycoside hydrolase, thermostability, ph optimum, clan gh-a, thermophile, alkalophile, hydrolase
• 由来する生物種: THIELAVIA HETEROTHALLICA (MYCELIOPHTHORA THERMOPHILA)
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 150923.61

構造登録者

Le Nours, J.,Ryttersgaard, C.,Lo Leggio, L.,Ostergaard, P.R.,Borchert, T.V.,Christensen, L.L.H.,Larsen, S. (登録日: 2003-02-27, 公開日: 2003-06-02, 最終更新日: 2024-10-23)

主引用文献

Le Nours, J.,Ryttersgaard, C.,Lo Leggio, L.,Ostergaard, P.R.,Borchert, T.V.,Christensen, L.L.H.,Larsen, S.
Structure of Two Fungal Beta-1,4-Galactanases: Searching for the Basis for Temperature and Ph Optimum
Protein Sci., 12:1195-, 2003

PubMed Abstract: beta-1,4-Galactanases hydrolyze the galactan side chains that are part of the complex carbohydrate structure of the pectin. They are assigned to family 53 of the glycoside hydrolases and display significant variations in their pH and temperature optimum and stability. Two fungal beta-1,4-galactanases from Myceliophthora thermophila and Humicola insolens have been cloned and heterologously expressed, and the crystal structures of the gene products were determined. The structures are compared to the previously only known family 53 structure of the galactanase from Aspergillus aculeatus (AAGAL) showing approximately 56% identity. The M. thermophila and H. insolens galactanases are thermophilic enzymes and are most active at neutral to basic pH, whereas AAGAL is mesophilic and most active at acidic pH. The structure of the M. thermophila galactanase (MTGAL) was determined from crystals obtained with HEPES and TRIS buffers to 1.88 A and 2.14 A resolution, respectively. The structure of the H. insolens galactanase (HIGAL) was determined to 2.55 A resolution. The thermostability of MTGAL and HIGAL correlates with increase in the protein rigidity and electrostatic interactions, stabilization of the alpha-helices, and a tighter packing. An inspection of the active sites in the three enzymes identifies several amino acid substitutions that could explain the variation in pH optimum. Examination of the activity as a function of pH for the D182N mutant of AAGAL and the A90S/ H91D mutant of MTGAL showed that the difference in pH optimum between AAGAL and MTGAL is at least partially associated with differences in the nature of residues at positions 182, 90, and/or 91.

PubMed: 12761390
DOI: 10.1110/PS.0300103

実験手法

X-RAY DIFFRACTION (1.87 Å)