Dispersin B:一种可用于生物被膜防治的糖苷水解酶

Dispersin B: a biofilm degrading glucoside hydrolase

β-N-乙酰氨基葡萄糖苷酶(dispersin B, DspB)是一种活性高、稳定性强的糖苷水解酶,其相对分子质量为40 000。DspB由361个氨基酸残基组成,具有8个β/a结构域,折叠后形成TIM桶状结构。其中,β4结构域存在高度保守的位点Asp183和Glu184。作为糖苷水解酶家族20(glycoside hydrolase family 20, GH20)成员,DspB不像其他β-己糖胺酶那样具有多个功能域,DspB只有单一的功能域,且具有独特的底物专一性、底物结合与释放特性。由于DspB能够水解细菌生物被膜基质中的聚β-(1,6)-N-乙酰葡萄糖胺(poly-β-1,6-N-acetyl-D-glucosamine, PNAG),使生物被膜发生解聚而变成游离状态,增加抗生素疗效,因此有望用于细菌引起的植入医疗器械感染的治疗。现分别从DspB所在GH20家族成员概况、DspB的结构和DspB的功能与应用三个方面对相关的最新研究进展进行分析与总结。

β-N-acetylglucosaminidase （dsipersin B, DspB） is an enzyme with the molecular weight of 40 kDa and consisting of a single polypeptide chain containing 361 residues. It is a highly active and stable glucoside hydrolase. It has 8 13/ct structures with a typical TIM barrel. The ]34 region of DspB is highly con- served, especially the residue Asp183 and Glu184. Although DspB belongs to glycoside hydrolase family 20 （GH20）, DspB is a single domain enzyme, which makes it different from other multi-domain 13-hexosamini- dases. And the onesingle-domain enzyme properties result in the unique characteristics of DspB, especially in the substrate specificity, banding, hydrolysis and release of products. Owing to the hydrolytic activities of DspB towards poly-β-（1,6）-N-acetyl-D-glucosamine （PNAG） polymer, which is the major component of bac- terium biofilm. The bacterium biofilm can be detached and become a planktonic stage, and this can increase the therapeutic effect of antibiotics. Therefore, DspB could be applied into the therapy of bacterium infection associated with medicine devices. This article briefly introduces the latest research progress in relation to the GH20 family members including DspB, the functions of DspB and the structure of DspB.