Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka, Japan.
Arch Insect Biochem Physiol. 2021 Jan;106(1):e21751. doi: 10.1002/arch.21751. Epub 2020 Oct 14.
D-3-phosphoglycerate dehydrogenase (PHGDH) is a key enzyme involved in the synthesis of l-serine. Despite the high serine content in silk proteins and the crucial role of PHGDH in serine biosynthesis, PHGDH has not been described in silkworms to date. Here, we identified PHGDH in the silkworm Bombyx mori and evaluated its biochemical properties. On the basis of the amino acid sequence and phylogenetic tree, this PHGDH has been categorized as a new type and designated as bmPHGDH. The recombinant bmPHGDH was overexpressed and purified to homogeneity. Kinetic studies revealed that PHGDH uses NADH as a coenzyme to reduce phosphohydroxypyruvate. High expression levels of bmphgdh messenger RNA (mRNA) were observed in the middle part of the silk gland and midgut in a standard strain of silkworm. Moreover, a sericin-deficient silkworm strain displayed reduced expression of bmphgdh mRNA. These findings indicate that bmPHGDH might play a crucial role in the provision of l-serine in the larva of B. mori.
3-磷酸甘油酸脱氢酶（PHGDH）是参与 l-丝氨酸合成的关键酶。尽管丝蛋白中含有高浓度的丝氨酸，并且 PHGDH 在丝氨酸生物合成中起着至关重要的作用，但迄今为止尚未在蚕中描述过 PHGDH。在这里，我们在家蚕 Bombyx mori 中鉴定了 PHGDH，并评估了其生化特性。根据氨基酸序列和系统发育树，该 PHGDH 被归类为新型，并命名为 bmPHGDH。重组 bmPHGDH 被过量表达并纯化为均一性。动力学研究表明，PHGDH 使用 NADH 作为辅酶还原磷酸羟丙酮酸。在标准家蚕品系中，丝腺和中肠的中间部分观察到 bmphgdh 信使 RNA（mRNA）的高表达水平。此外，丝胶缺陷型家蚕品系显示 bmphgdh mRNA 的表达降低。这些发现表明 bmPHGDH 可能在家蚕幼虫中提供 l-丝氨酸方面发挥着关键作用。
