Vitamin B6 metabolism in the Gram-positive model bacterium Bacillus subtilis

术语“维生素B6”统称为维生素吡哆醛(PL)、吡哆醇(PN)和吡哆胺(PM)，以及各自的磷酸酯吡哆醛5‘-磷酸(PLP)、吡哆醇5’-磷酸(PNP)和吡哆胺5‘-磷酸(PMP)。PLP是最重要的B6维生素，因为它是许多蛋白质和酶的辅因子。在革兰氏阳性模式菌中，枯草芽孢杆菌至少有65种蛋白质需要PLP才能发挥作用。枯草杆菌依赖于脱氧硫糖-磷酸(DXP)非依赖的PdxST酶复合体来合成PLP。其他生物通过依赖DXP的途径合成PLP，该途径涉及七个酶反应。还观察到枯草杆菌可以从环境中摄取B6维生素PL和Pn来产生PLP。然而，B6维生素的运输系统尚不清楚。在拟议的项目中，我们希望确定第一个细菌维生素B6转运体。此外，我们的目的是阐明谷氨酰胺酶PdxT在PLP合成中的作用以及反应性B6维生素是如何转移到靶蛋白上的。最近，我们发现两个基因组改变足以使枯草杆菌菌株通过截短的依赖于DXP的途径产生PLP，该途径只由两个非天然酶组成。遗传分析表明，功能未知的YtoQ蛋白参与了维生素B6的生物合成。通过应用遗传学和生物化学方法，我们旨在阐明YtoQ蛋白的生理作用。此外，为了揭示新的维生素B6生物合成途径是如何运作的，我们将进行代谢组分析。

The term "vitamin B6" collectively designates the vitamers pyridoxal (PL), pyridoxine (PN), and pyridoxamine (PM), and the respective phosphate esters pyridoxal 5’-phosphate (PLP), pyridoxine 5’-phosphate (PNP), and pyridoxamine 5’-phosphate (PMP). PLP is the most important B6 vitamer because it serves as a cofactor for many proteins and enzymes. In the Gram-positive model bacterium Bacillus subtilis at least 65 proteins require PLP for function. B. subtilis relies on the deoxyxylulose-phosphate (DXP)-independent PdxST enzyme complex for PLP synthesis. Other organisms synthesize PLP via the DXP-dependent pathway, which involves seven enzymatic reactions. It has also been observed that B. subtilis can take up the B6 vitamers PL and PN from the environment to produce PLP. However, the transport systems for the B6 vitamers are unknown. In the proposed project, we want to identify the first bacterial vitamin B6 transporter. Moreover, we aim to elucidate the role of the glutaminase PdxT in PLP synthesis and how the reactive B6 vitamer is transferred to the target proteins. Recently, we have found that two genomic alterations are sufficient to allow a B. subtilis strain to produce PLP via a truncated DXP-dependent pathway consisting of only two non-native enzymes. Genetic analyses revealed that the YtoQ protein of unknown function is involved in vitamin B6 biosynthesis. By applying genetic as well as biochemical approaches we aim to elucidate the physiological role of the YtoQ protein. Furthermore, to unravel how the novel vitamin B6 biosynthetic route operates, we will perform metabolome analyses.