Haque Mohammad R, Hirowatari Aiko, Koyanagi Ayumi, Ichinose Takashi, Abiru Maiko, Mohri Shinya, Furuya Shigeki, Yamamoto Kohji
Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Arch Insect Biochem Physiol. 2019 Jun;101(2):e21553. doi: 10.1002/arch.21553. Epub 2019 Apr 19.
In this study, we identified and characterized a phosphoserine aminotransferase (bmPSAT) from Bombyx mori (B. mori) that is responsible for l-serine biosynthesis. A complementary DNA that encodes bmPSAT was cloned by reverse transcriptase polymerase reaction and sequenced. The presumed amino acid sequence revealed 47-87% identity with known PSATs from insects, humans, plants, and bacteria. Through phylogenetic analysis, we found that bmPSAT is evolutionary related to insect PSATs. Recombinant bmPSAT was produced in Escherichia coli by using a cold-shock promotor and purified to homogeneity. This enzyme utilizes phosphohydroxypyruvate and glutamate for transamination. bmPSAT messenger RNA (mRNA) was expressed at higher levels in several tissues of standard strain silkworm including the silk gland, whereas a sericin-deficient silkworm strain exhibited a diminished expression of bmPSAT mRNA in the silk gland. These findings indicate that bmPSAT may play an important role in synthesizing and supplying l-serine in the larva of B. mori.
在本研究中，我们鉴定并表征了家蚕中一种负责L-丝氨酸生物合成的磷酸丝氨酸转氨酶（bmPSAT）。通过逆转录聚合酶反应克隆了编码bmPSAT的互补DNA并进行了测序。推测的氨基酸序列与来自昆虫、人类、植物和细菌的已知PSAT具有47%-87%的同一性。通过系统发育分析，我们发现bmPSAT与昆虫PSAT在进化上相关。利用冷休克启动子在大肠杆菌中产生重组bmPSAT并纯化至同质。该酶利用磷酸羟基丙酮酸和谷氨酸进行转氨作用。bmPSAT信使核糖核酸（mRNA）在标准品系家蚕的几个组织中，包括丝腺，表达水平较高，而丝胶蛋白缺陷型家蚕品系在丝腺中bmPSAT mRNA的表达降低。这些发现表明bmPSAT可能在家蚕幼虫L-丝氨酸的合成和供应中起重要作用。
