24TE

Crystal structure of GH30 Streptomyces avermitilis endo-beta-1,6-galactanase complexed with Gal-beta1,6-Gal

24TE の概要

• エントリーDOI: 10.2210/pdb24te/pdb
• 分子名称: Secreted endo-beta-1,6-galactanase, beta-D-galactopyranose-(1-6)-beta-D-galactopyranose, SULFATE ION, ... (6 entities in total)
• 機能のキーワード: glycoside hydrolase family 30, hydrolase
• 由来する生物種: Streptomyces avermitilis MA-4680 = NBRC 14893
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 53457.77

構造登録者

Fujimoto, Z.,Kishine, N.,Kaneko, S. (登録日: 2026-03-19, 公開日: 2026-08-12)

主引用文献

Fujimoto, Z.,Kishine, N.,Kotake, T.,Kaneko, S.
Crystal structure of endo-beta-1,6-galactanase from Streptomyces avermitilis.
Acta Crystallogr D Struct Biol, 82:962-971, 2026

PubMed Abstract: Endo-β-1,6-galactanases hydrolyze β-1,6-linked galactosyl linkages in galactans, yielding β-1,6-linked galacto-oligosaccharides, predominantly galactobiose. Here, we report to our knowledge the first crystal structure of an endo-β-1,6-galactanase, together with its β-1,6-galactobiose-bound complex, revealing the structural basis for substrate recognition by this enzyme. Endo-β-1,6-galactanase from Streptomyces avermitilis (Sa16Gal30A) is a member of glycoside hydrolase family 30 (GH30) subfamily 5. Sa16Gal30A consists of two structural domains: a catalytic (β/α)-barrel domain and an appended β-sandwich domain. The β-1,6-galactobiose complex structure revealed two β-1,6-galactobiose molecules bound within the catalytic domain: one at the catalytic site and another at the distinct surface site distal to the catalytic center. This structure represents the first reported structure of a GH30 subfamily 5 enzyme and provides structural insights into the molecular basis of β-1,6-galactan recognition within the catalytic cleft. Sa16Gal30A possesses three extended regions, loops 2, 4 and 8, in the catalytic domain compared with enzymes from other GH30 subfamilies, and these loops appear to modulate substrate specificity towards β-1,6-galactan by shaping the architecture of the catalytic cleft. In addition, a secondary β-1,6-galactan-binding site was identified at a distal location, which may function as a distal subsite, thereby facilitating the efficient hydrolysis of long β-1,6-galactan chains.

PubMed: 42478457
DOI: 10.1107/S2059798326006133

実験手法

X-RAY DIFFRACTION (2 Å)