鉴定枯草芽孢杆菌膜结合型短链多谷氨酸及其生化特性。

Identification and biochemical characterization of membranous short-chain polyglutamate from Bacillus subtilis.

机构信息

Department of Bioresources Science, Kochi University, Nankoku, Kochi 783-8502, Japan.

出版信息

Chem Biodivers. 2010 Jun;7(6):1563-72. doi: 10.1002/cbdv.200900238.

DOI:10.1002/cbdv.200900238

PMID:20564574

Abstract

It is generally thought that natural strains of Bacillus subtilis produce poly-gamma-glutamate (PGA) as a large exopolymer (over 1,000 kDa) with high water solubility. However, extracellular PGA (ePGA) of B. subtilis is actually diverse in molecular size and configuration. In this study, we identified membranous PGA (mPGA) from both natural and domestic strains of B. subtilis. In contrast to ePGA, mPGA was relatively small and consistently l-glutamate-rich. Genetic analysis revealed that the pgs operon of B. subtilis is responsible for mPGA production as well as ePGA production. Biochemical analyses using the membranous fractions from B. subtilis ssp. chungkookjang indicated that the presence of zinc ions (Zn(2+)) affected both the membrane association of mPGA and in vitro synthesis (elongation) of PGA. Our observations highlighted three important factors that will affect the structural diversity of B. subtilis PGA, namely the occurrence of mPGA, the effects of Zn(2+), and the configuration of glutamate substrate.

摘要

人们普遍认为枯草芽孢杆菌天然菌株会产生聚-γ-谷氨酸（PGA）作为一种具有高水溶性的大型胞外聚合物（超过 1000 kDa）。然而，枯草芽孢杆菌的细胞外 PGA（ePGA）在分子大小和结构上实际上是多种多样的。在这项研究中，我们从枯草芽孢杆菌的天然菌株和国内菌株中鉴定出了膜 PGA（mPGA）。与 ePGA 不同，mPGA 相对较小且始终富含 l-谷氨酸。遗传分析表明，枯草芽孢杆菌的 pgs 操纵子负责 mPGA 的产生以及 ePGA 的产生。使用来自枯草芽孢杆菌 ssp. chungkookjang 的膜部分进行的生化分析表明，锌离子（Zn(2+)）的存在会影响 mPGA 的膜结合以及 PGA 的体外合成（延伸）。我们的观察结果强调了三个重要因素，它们将影响枯草芽孢杆菌 PGA 的结构多样性，即 mPGA 的发生、Zn(2+)的影响以及谷氨酸底物的构型。