Glucosamine: fructose-6-phosphate amidotransferase in the white shrimp Litopenaeus vannamei: characterization and regulation under alkaline and cadmium stress

Abstract

Heavy metal residues and chemical contaminators considered as relevant sources of aquatic environmental pollutants have a generally immunosuppressive effect on aquatic organisms, depressing metabolic activities and immune response. Glutamine: fructose-6-phosphate aminotransferase (GFAT, EC2.6.1.16) is the first, and rate-limiting, enzyme in the hexosamine biosynthetic pathway, and is involved in the regulation of chitin biosynthesis and glycosylation of proteins. We have isolated and characterized GFAT from the white shrimp Litopenaeus vannamei. Amino acid sequence similarity of the Lv-GFAT (L.vannamei-GFAT) was highest to GFATs isolated from insects and mammals (83 % similarity to that of Haemaphysalis longicornis). The open-reading frame of the Lv-GFAT codes for a protein of 41.6 kDa with a calculated isoelectric point of 5.03. RT-PCR assays showed that endogenous Lv-GFAT mRNA is most strongly expressed in the intestine. Further analysis of Lv-GFAT gene expression in hepatopancreas by quantitative real-time PCR demonstrated that Lv-GFAT transcript levels increased when the shrimp were exposed to alkaline pH (9.3) and cadmium stress, but the time when its mRNA expression level peaked differed under these stresses. We also first expressed the recombinant protein of GFAT from shrimps in Escherichia coli. Western blot analyses confirmed that the Lv-GFAT protein was strongly expressed in the hepatopancreas after exposure to the LC-Cd stress. These results suggest that Lv-GFAT expression is stimulated by alkaline pH and cadmium stress and that it may play important roles in resistance of shrimp to environmental stresses.

Impact of Three Thiazolidinone Compounds with Piperine Skeletons on Trehalase Activity and Development of Spodoptera frugiperda Larvae

“…42,69,70 For instance, when Litopenaeus vannamei is exposed to alkaline pH conditions and cadmium stress, LvGFAT is strongly expressed in the liver, indicating its importance in environmental stress resistance. 71 Inhibition of GFAT expression can significantly increase the deformity and mortality rates in Nilaparvata lugens. 72 Bolognesi et al 73 reported that Sf CHSB and Sf CHI are highly expressed in the midgut epithelium.…”

“…frugiperda larvae was less than 50% (Figure A) following treatment with larvae 6a, 7b, and 7e, primarily owing to abnormal chitin metabolism. Previous studies have shown that GFAT and GNAPNA play regulatory roles in chitin biosynthesis. ,, For instance, when Litopenaeus vannamei is exposed to alkaline pH conditions and cadmium stress, LvGFAT is strongly expressed in the liver, indicating its importance in environmental stress resistance . Inhibition of GFAT expression can significantly increase the deformity and mortality rates in Nilaparvata lugens .…”

Proteogenomic Study of the Effect of an Improved Mixed Diet of Live Preys on the Aquaculture of Octopus vulgaris Paralarvae

“…The GFAT controls the flux of glucose into the hexosamine pathway and is involved in the regulation of glycosylation of proteins; and the NDK protein may display multiple functions in diverse biological processes and is involved in the promotion of cancer. Transcripts coding for these proteins have been upregulated in response to several stressors, including viral infection in the white shrimp (Litopenaeus vannamei) (Liu et al, 2015(Liu et al, , 2017, which would indicate that paralarvae fed on A diet would be in poorer condition than those fed on M diet. In fact, caspase 3 that is involved in the apoptotic process was over-expressed in the A group.…”