Molecular Cloning and Functional Characterization of a Hexokinase from the Oriental River Prawn Macrobrachium nipponense in Response to Hypoxia

Metabolic adjustment to hypoxia in Macrobrachium nipponense (oriental river prawn) implies a shift to anaerobic metabolism. Hexokinase (HK) is a key glycolytic enzyme in prawns. The involvement of HK in the hypoxia inducible factors (HIFs) pathway is unclear in prawns. In this study, the full-length cDNA for HK (MnHK) was obtained from M. nipponense, and its properties were characterized. The full-length cDNA (2385 bp) with an open reading frame of 1350 bp, encoded a 450-amino acid protein. MnHK contained highly conserved amino acids in the glucose, glucose-6-phosphate, ATP, and Mg+2 binding sites. Quantitative real-time reverse transcription PCR assays revealed the tissue-specific expression pattern of MnHK, with abundant expression in the muscle, and gills. Kinetic studies validated the hexokinase activity of recombinant HK. Silencing of HIF-1α or HIF-1β subunit genes blocked the induction of HK and its enzyme activities during hypoxia in muscles. The results suggested that MnHK is a key factor that increases the anaerobic rate, and is probably involved in the HIF-1 pathway related to highly active metabolism during hypoxia.