Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan.
Biosci Biotechnol Biochem. 2021 Feb 18;85(2):351-358. doi: 10.1093/bbb/zbaa044.
Methionine is a canonical amino acid. The protein MetX is a homoserine O-acyltransferase utilized in the methionine biosynthetic pathway. The metW gene is found adjacent to the metX gene in some bacteria, but its functions are unclear. In this study, I focused on the function of MetW and MetX from Pseudomonas aeruginosa (PaMetW and PaMetX). I demonstrated that PaMetW interacted with and activated the homoserine O-succinyltransferase (HST) activity of PaMetX. Furthermore, I elucidated that the HST activity of PaMetX in complex with PaMetW was inhibited by the addition of S-adenosyl-l-homocysteine (SAH), although PaMetX alone showed no feedback inhibition. Since PaMetW possesses a glycine-rich sequence annotated as a SAM/SAH binding site, I also investigated the relationship between this glycine-rich sequence and the inhibition caused by SAH. I revealed that alanine mutation of PaMetW Gly24 reduced the inhibitory effect of SAH. These results suggest that MetW is a regulatory protein of MetX.
蛋氨酸是一种典型的氨基酸。MetX 蛋白是甲硫氨酸生物合成途径中用到的同型丝氨酸 O-酰基转移酶。一些细菌的 metW 基因与 metX 基因相邻，但它的功能尚不清楚。在这项研究中，我专注于铜绿假单胞菌（PaMetW 和 PaMetX）的 MetW 和 MetX 的功能。我证明了 PaMetW 与 PaMetX 的同型丝氨酸 O-琥珀酰基转移酶（HST）活性相互作用并激活了该酶的活性。此外，我阐明了 PaMetW 与 PaMetX 形成复合物时，PaMetX 的 HST 活性受到 S-腺苷甲硫氨酸（SAH）的抑制，尽管单独的 PaMetX 没有反馈抑制。由于 PaMetW 具有一个甘氨酸丰富的序列，注释为 SAM/SAH 结合位点，我还研究了这个富含甘氨酸的序列与 SAH 引起的抑制之间的关系。我发现 PaMetW 的丙氨酸突变 24 减少了 SAH 的抑制作用。这些结果表明 MetW 是 MetX 的调节蛋白。
