1CWY

CRYSTAL STRUCTURE OF AMYLOMALTASE FROM THERMUS AQUATICUS, A GLYCOSYLTRANSFERASE CATALYSING THE PRODUCTION OF LARGE CYCLIC GLUCANS

1CWY の概要

• エントリーDOI: 10.2210/pdb1cwy/pdb
• 分子名称: AMYLOMALTASE (2 entities in total)
• 機能のキーワード: (beta, alpha)8 barrel, transferase
• 由来する生物種: Thermus aquaticus
• 細胞内の位置: Cytoplasm : O87172
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 57293.04

構造登録者

Przylas, I.,Tomoo, K.,Terada, Y.,Takaha, T.,Fuji, K.,Saenger, W.,Straeter, N. (登録日: 1999-08-27, 公開日: 2001-02-28, 最終更新日: 2024-02-07)

主引用文献

Przylas, I.,Tomoo, K.,Terada, Y.,Takaha, T.,Fujii, K.,Saenger, W.,Strater, N.
Crystal structure of amylomaltase from thermus aquaticus, a glycosyltransferase catalysing the production of large cyclic glucans.
J.Mol.Biol., 296:873-886, 2000

PubMed Abstract: Amylomaltase is involved in the metabolism of starch, one of the most important polysaccharides in nature. A unique feature of amylomaltase is its ability to catalyze the formation of cyclic amylose. In contrast to the well studied cyclodextrin glucanotransferases (CGTases), which synthesize cycloamylose with a ring size (degree of polymerization or DP) of 6-8, the amylomaltase from Thermus aquaticus produces cycloamyloses with a DP of 22 and higher. The crystal structure of amylomaltase from Thermus aquaticus was determined to 2.0 A resolution. It is a member of the alpha-amylase superfamily of enzymes, whose core structure consists of a (beta, alpha)(8) barrel. In amylomaltase, the 8-fold symmetry of this barrel is disrupted by several insertions between the barrel strands. The largest insertions are between the third and fifth barrel strands, where two insertions form subdomain B1, as well as between the second and third barrel strands, forming the alpha-helical subdomain B2. Whereas part of subdomain B1 is also present in other enzyme structures of the alpha-amylase superfamily, subdomain B2 is unique to amylomaltase. Remarkably, the C-terminal domain C, which is present in all related enzymes of the alpha-amylase family, is missing in amylomaltase. Amylomaltase shows a similar arrangement of the catalytic side-chains (two Asp residues and one Glu residue) as in previously characterized members of the alpha-amylase superfamily, indicating similar mechanisms of the glycosyl transfer reaction. In amylomaltase, a conserved loop of around eight amino acid residues is partially shielding the active center. This loop, which is well conserved among other amylomaltases, may sterically hinder the formation of small cyclic products.

PubMed: 10677288
DOI: 10.1006/jmbi.1999.3503

実験手法

X-RAY DIFFRACTION (2 Å)