Clone and functional analysis of Seryl-tRNA synthetase and Tyrosyl-tRNA synthetase from silkworm, Bombyx mori

Abstract

Aminoacyl-tRNA synthetases are the key enzymes for protein synthesis. Glycine, alanine, serine and tyrosine are the major amino acids composing fibroin of silkworm. Among them, the genes of alanyl-tRNA synthetase (AlaRS) and glycyl-tRNA synthetase (GlyRS) have been cloned. In this study, the seryl-tRNA synthetase (SerRS) and tyrosyl-tRNA synthetase (TyrRS) genes from silkworm were cloned. Their full length are 1709 bp and 1868 bp and contain open reading frame (ORF) of 1485 bp and 1575 bp, respectively. RT-PCR examination showed that the transcription levels of SerRS, TyrRS, AlaRS and GlyRS are significantly higher in silk gland than in other tissues. In addition, their transcription levels are much higher in middle and posterior silk gland than in anterior silk gland. Moreover, treatment of silkworms with phoxim, an inhibitor of silk protein synthesis, but not TiO2 NP, an enhancer of silk protein synthesis, significantly reduced the transcription levels of aaRS and content of free amino acids in posterior silk gland, therefore affecting silk protein synthesis, which may be the mechanism of phoxim-silking disorders. Furthermore, low concentration of TiO2 NPs showed no effect on the transcription of aaRS and content of free amino acids, suggesting that TiO2 NPs promotes silk protein synthesis possibly by increasing the activity of fibroin synthase in silkworm.

Unique Material Properties of Bombyx mori Silk Fiber Incorporated with 3-Azidotyrosine

“…AQM56846). The catalytic domain of TyrRS is located in its N-terminal region and TyrRS from Saccharomyces cerevisiae (ScTyrRS) was previously mutated in its catalytic domain (Tyr43 to Gly) to recognize an azido-bearing synthetic tyrosine analogue, 3-AzTyr, as a substrate. , We compared the amino acid sequence of BmTyrRS with that of ScTyrRS (Figure S1), which revealed high homology in their N-terminal catalytic domains (Figure ). Since the Tyr43 of ScTyrRS corresponds to the Tyr36 of BmTyrRS, we generated a BmTyrRS mutant with Tyr36 to Gly (Y36G) mutation to confer catalytic activity toward 3-AzTyr.…”

Metabonomic Analysis of Silkworm Midgut Reveals Differences between the Physiological Effects of an Artificial and Mulberry Leaf Diet

“…For the silk proteins, Gly, alanine (Ala), serine (Ser), and tyrosine (Tyr) account for more than 85% of the total amino acids [12,36,37]. The silk proteins of B. mori are mainly composed of sericin and silk fibroin [38,39], and amino acids such as Gly and Ser play an important role in silk fibroin synthesis [40]. In this study, a great deal of differential metabolite enrichment in the Gly, Ser, and threonine (Thr) metabolic pathways was detected in the midgut of male silkworms fed on ML and AD, but not in female silkworms.…”