D‐3‐phosphoglycerate dehydrogenase from the silkworm Bombyx mori: Identification, functional characterization, and expression

Abstract

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.

The Phosphoserine Phosphatase Alters the Free Amino Acid Compositions and Fecundity in Cyrtorhinus lividipennis Reuter

“…Additionally, the mammalian delta (1)-pyrroline-5-carboxylate synthase (P5CS) is found to be highly interactive with ClPSP, which is a bifunctional ATP- and NAD(P)H-dependent mitochondrial enzyme that catalyzes the complex phosphorylation and reduction-conversion of L-glutamate to P5C, a pivotal step in the biosynthesis of L-proline, L-ornithine, and L-arginine. Serine-pyruvate aminotransferase (spat) pyridoxal phosphate binding, alanine-glyoxylate transaminase activity, and serine-pyruvate transaminase activity, primarily involved in the biological process described with the glyoxylate catabolic process, are found with high interaction with ClPSP protein [ 26 ]. Moreover, other proteins/enzymes (serine hydroxy methyltransferase, serine-pyruvate aminotransferase, cystathionine beta-synthase) are found to be highly interactive with our reference protein.…”