Molecular cloning and characterization of acyl-CoA binding protein (ACBP) gene from shrimp Penaeus monodon exposed to salinity stress

Abstract

Acyl-CoA binding protein (ACBP), a protein present ubiquitously in wide range of organisms play significant role in transport of acyl groups for macromolecular biosynthesis involved in various functional and regulatory processes. In crustaceans, ACBP has functional role in growth, reproduction and temperature tolerance. In the present study, two suppression subtractive hybridization (SSH) cDNA libraries were performed using gut tissues of shrimp Penaeus monodon exposed to low (3ppt) and high (55ppt) salinity stress conditions. SSH library resulted in identification of differentially expressed genes that belonged to various functional classes such as the nucleic acid regulation and replication, defence proteins, allergen protein, signal transduction pathways, apoptosis, energy and metabolism, cell cycle regulation and hypothetical proteins. ACBP was identified as one of the differentially expressed gene in both the SSH libraries of shrimp P. monodon subjected to low and high salinity stress. The full-length cDNA of P. monodon ACBP gene was isolated and the sequence revealed 273bp open reading frame encoding 90 amino acids with molecular mass of 10kDa and pI 6.8. The ORF showed presence of four phosphorylation sites, with absence of signal peptide sequence and glycosylation sites. The deduced amino acid sequence of ACBP exhibited high sequence identity (92%) with ACBP class of protein identified from Fenneropenaeus chinensis. Real time PCR analysis of shrimps subjected to 3ppt salinity conditions after 2weeks revealed an increase in expression of ACBP transcripts, in the gut (28.08-folds), gills (11.71-folds) and in the muscle tissues (1.70-folds). Whereas, shrimps exposed to 55ppt salinity conditions after 2weeks exhibited increased ACBP transcript levels in the gut (11.95-folds), gills (1.052-folds) and muscle tissues (7.35-folds). The significant increase in expression levels of ACBP in various tissues of shrimps suggests a functional role of this gene in salinity stress tolerance and adaptation.