Graduate Institute of Biotechnology, National Chung Hsing University, 250 Kuo-Kuang Rd, Taichung, 40227, Taiwan.
Microb Cell Fact. 2009 Nov 25;8:62. doi: 10.1186/1475-2859-8-62.
The 190-kDa Paenibacillus beta-1,3-glucanase (LamA) contains a catalytic module of the glycoside hydrolase family 16 (GH16) and several auxiliary domains. Of these, a discoidin domain (DS domain), present in both eukaryotic and prokaryotic proteins with a wide variety of functions, exists at the carboxyl-terminus. To better understand the bacterial DS domain in terms of its structure and function, this domain alone was expressed in Escherichia coli and characterized. The results indicate that the DS domain binds various polysaccharides and enhances the biological activity of the GH16 module on composite substrates. We also investigated the importance of several conserved aromatic residues in the domain's stability and substrate-binding affinity. Both were affected by mutations of these residues; however, the effect on protein stability was more notable. In particular, the forces contributed by a sandwiched triad (W1688, R1756, and W1729) were critical for the presumable beta-sandwich fold.
190kDa 短小芽孢杆菌β-1,3-葡聚糖酶（LamA）包含糖苷水解酶家族 16（GH16）的催化模块和几个辅助结构域。其中，盘菌结构域（DS 结构域）存在于具有广泛功能的真核和原核蛋白中，位于羧基末端。为了更好地理解细菌 DS 结构域在结构和功能方面的特征，我们单独在大肠杆菌中表达了这个结构域并对其进行了表征。结果表明，DS 结构域可以结合各种多糖，并增强 GH16 模块在复合底物上的生物活性。我们还研究了该结构域中几个保守芳香族残基对其稳定性和底物结合亲和力的重要性。突变这些残基会影响两者；然而，对蛋白质稳定性的影响更为显著。特别是，由三明治三联体（W1688、R1756 和 W1729）贡献的力对于假定的β-折叠至关重要。
