Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, Alicante, Spain.
PLoS One. 2013 Jul 26;8(7):e69307. doi: 10.1371/journal.pone.0069307. Print 2013.
The phosphotransferase system (PTS) is involved in the use of carbon sources in bacteria. Bacillus sphaericus, a bacterium with the ability to produce insecticidal proteins, is unable to use hexoses and pentoses as the sole carbon source, but it has ptsHI genes encoding the two general proteins of the PTS: enzyme I (EI) and the histidine phosphocarrier (HPr). In this work, we describe the biophysical and structural properties of HPr from B. sphaericus, HPr(bs), and its affinity towards EI of other species to find out whether there is inter-species binding. Conversely to what happens to other members of the HPr family, HPr(bs) forms several self-associated species. The conformational stability of the protein is low, and it unfolds irreversibly during heating. The protein binds to the N-terminal domain of EI from Streptomyces coelicolor, EIN(sc), with a higher affinity than that of the natural partner of EIN(sc), HPr(sc). Modelling of the complex between EIN(sc) and HPr(bs) suggests that binding occurs similarly to that observed in other HPr species. We discuss the functional implications of the oligomeric states of HPr(bs) for the glycolytic activity of B. sphaericus, as well as a strategy to inhibit binding between HPr(sc) and EIN(sc).
磷酸转移酶系统 (PTS) 参与细菌对碳源的利用。球形芽孢杆菌是一种能够产生杀虫蛋白的细菌，它不能将己糖和戊糖作为唯一的碳源，但它有编码 PTS 两个通用蛋白的 ptsHI 基因：酶 I (EI) 和组氨酸磷酸载体 (HPr)。在这项工作中，我们描述了球形芽孢杆菌 HPr（HPr(bs)）的生物物理和结构特性及其与其他物种 EI 的亲和力，以了解是否存在种间结合。与 HPr 家族的其他成员不同，HPr(bs) 形成了几种自身相关的物种。该蛋白的构象稳定性较低，在加热过程中不可逆地展开。该蛋白与链霉菌 EI 的 N 端结构域 EIN(sc) 结合具有更高的亲和力，高于其天然伴侣 HPr(sc)。EIN(sc) 和 HPr(bs) 之间复合物的建模表明，结合方式与在其他 HPr 物种中观察到的相似。我们讨论了 HPr(bs) 的寡聚状态对球形芽孢杆菌糖酵解活性的功能意义，以及一种抑制 HPr(sc) 和 EIN(sc) 之间结合的策略。
