Dipartimento di Biologia Animale e dell'Uomo, University of Torino, Torino, Italy.
Proteomics. 2011 Jun;11(11):2212-21. doi: 10.1002/pmic.201000747. Epub 2011 May 5.
Selenium (Se), Se-cysteines and selenoproteins have received growing interest in the nutritional field as redox-balance modulating agents. The aim of this study was to establish the Se-concentrating and Se-metabolizing capabilities of the probiotic Lactobacillus reuteri Lb26 BM, for nutraceutical applications. A comparative proteomic approach was employed to study the bacteria grown in a control condition (MRS modified medium) and in a stimulated condition (4.38 mg/L of sodium selenite). The total protein extract was separated into two pI ranges: 4-7 and 6-11; the 25 identified proteins were divided into five functional classes: (i) Se metabolism; (ii) energy metabolism; (iii) stress/adhesion; (iv) cell shape and transport; (v) proteins involved in other functions. All the experimental results indicate that L. reuteri Lb26 BM is able to metabolize Se(IV), incorporating it into selenoproteins, through the action of a selenocysteine lyase, thus enhancing organic Se bioavailability. This involves endo-ergonic reactions balanced by an increase of substrate-level phosphorylation, chiefly through lactic fermentation. Nevertheless, when L. reuteri was grown on Se a certain degree of stress was observed, and this has to be taken into account for future applicative purposes. The proteomic approach has proven to be a powerful tool for the metabolic characterization of potential Se-concentrating probiotics.
硒（Se）、硒半胱氨酸和硒蛋白作为氧化还原平衡调节剂，在营养领域受到越来越多的关注。本研究旨在确定益生菌乳杆菌 Lb26 BM 的浓缩硒和代谢硒的能力，以用于营养保健品应用。采用比较蛋白质组学方法研究了在对照条件（改良 MRS 培养基）和刺激条件（4.38mg/L 亚硒酸钠）下生长的细菌。将总蛋白提取物分离为两个等电范围：4-7 和 6-11；鉴定出的 25 种蛋白质分为五类：（i）硒代谢；（ii）能量代谢；（iii）应激/粘附；（iv）细胞形态和运输；（v）参与其他功能的蛋白质。所有实验结果表明，L. reuteri Lb26 BM 能够通过硒半胱氨酸裂解酶的作用将 Se(IV)代谢为硒蛋白，从而提高有机硒的生物利用度。这涉及到通过主要通过乳酸发酵的底物水平磷酸化来平衡的内吸能反应。然而，当 L. reuteri 在 Se 上生长时，观察到一定程度的应激，这在未来的应用中必须考虑到。蛋白质组学方法已被证明是对潜在浓缩硒益生菌进行代谢特征描述的有力工具。
