WRS-85D: A Tryptophanyl-tRNA Synthetase Expressed to High Levels in the DevelopingDrosophilaSalivary Gland

Abstract

In a screen for genes expressed in the Drosophila embryonic salivary gland, we identified a tryptophanyl-tRNA synthetase gene that maps to cytological position 85D (WRS-85D). WRS-85D expression is dependent on the homeotic gene Sex combs reduced (Scr). In the absence of Scr function, WRS-85D expression is lost in the salivary gland primordia; conversely, ectopic expression of Scr results in expression of WRS-85D in new locations. Despite the fact that WRS-85D is a housekeeping gene essential for protein synthesis, we detected both WRS-85D mRNA and protein at elevated levels in the developing salivary gland. WRS-85D is required for embryonic survival; embryos lacking the maternal contribution were unrecoverable, whereas larvae lacking the zygotic component died during the third instar larval stage. We showed that recombinant WRS-85D protein specifically charges tRNA Trp , and WRS-85D is likely to be the only tryptophanyl-tRNA synthetase gene in Drosophila. We characterized the expression patterns of all 20 aminoacyl-tRNA synthetases and found that of the four aminoacyl-tRNA synthetase genes expressed at elevated levels in the salivary gland primordia, WRS-85D is expressed at the highest level throughout embryogenesis. We also discuss the potential noncanonical activities of tryptophanyl-tRNA synthetase in immune response and regulation of cell growth.

Gene expression changes in Schistosoma mansoni sporocysts induced by Biomphalaria glabrata embryonic cells

“…AARS are considered to be housekeeping enzymes but in E. coli a metabolic control of the expression of the GlnRS gene occurs at the transcriptional level (Cheung et al 1985). Similar results were also obtained by Hall and Yanofsky (1982) with E. coli and by Seshaiah and Andrew (1999) with the D. melanogaster tryptophanyltRNA synthetases. All these data show that the level of AARS, including GlnRS, increases during growth and is therefore in agreement with the higher levels of SmGlnRS transcripts observed in developing sporocysts.…”

Drosophilaventral furrow morphogenesis: a proteomic analysis

“…RSs are generally thought of as housekeeping genes. However, the expression of specific RSs appears to be developmentally regulated in a tissue-specific manner in Drosophila embryos (Seshaiah and Andrews, 1999). During mammalian apoptosis, tyr-RS has been shown to be cleaved to generate two different cytokines (Wakasugi and Schimmel, 1999).…”

Novel regulatory interactions and activities of mammalian tRNA synthetases

“…For example, Seshaiah and Andrew [32] demonstrated that each ARS is uniquely expressed in different tissues and developmental stages of Drosophila. In particular, WRS is highly induced upon cellular exposure to interferon because its promoter contains an interferon responsive region [33,34].…”