Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University Graduate School, Fukuoka, Japan.
Insect Mol Biol. 2020 Feb;29(1):48-55. doi: 10.1111/imb.12609. Epub 2019 Jul 25.
Phosphoserine phosphatase (PSP) catalyses the synthesis of l-serine via the phosphorylated pathway by facilitating the dephosphorylation of phosphoserine. A cDNA encoding PSP from the silkworm Bombyx mori (bmPSP) was isolated using reverse transcription-PCR and then sequenced. The resulting clone encoded 236 amino acids with a molecular weight of 26 150, exhibiting 14-60% sequence identity with other PSPs. The recombinant PSP was overexpressed in Escherichia coli and purified. Kinetic studies showed that bmPSP possessed activity toward l-phosphoserine, and Asp20, Asp22 and Asp204 in bmPSP were found to be critical for modulating bmPSP activity. Real-time PCR analysis provided evidence that the amount of bmpsp transcript was reduced in middle silk glands of a sericin-deficient silkworm strain. These findings revealed that bmPSP may play important roles in synthesizing one-carbon donors of l-serine, which is abundant in silk, as well as other cell metabolites in B. mori.
磷酸丝氨酸磷酸酶（PSP）通过促进磷酸丝氨酸的去磷酸化，催化 l-丝氨酸的合成途径。使用反转录-PCR 从家蚕（Bombyx mori）中分离到编码 PSP 的 cDNA，然后对其进行测序。所得克隆编码 236 个氨基酸，分子量为 26150，与其他 PSP 具有 14-60%的序列同一性。重组 PSP 在大肠杆菌中过表达并纯化。动力学研究表明，bmPSP 对 l-磷酸丝氨酸具有活性，并且 bmPSP 中的 Asp20、Asp22 和 Asp204 被发现对调节 bmPSP 活性至关重要。实时 PCR 分析提供的证据表明，在缺乏丝胶的家蚕品系的中部丝腺中，bmpsp 转录本的数量减少。这些发现表明，bmPSP 可能在家蚕中发挥重要作用，合成 l-丝氨酸的一碳供体，而 l-丝氨酸在丝中含量丰富，也是其他细胞代谢物的来源。
