Cloning and sequencing of cDNA encoding glutamine synthetase from the sea anemone Aiptasia pallida

Glutamine synthetase (GS) catalyzes the addition of ammonium to glutamic acid to form glutamine and plays a crucial role in the nitrogen assimilation of the sea anemone Aiptasia pallida and its endosymbiotic algae. We describe the cDNA cloning and sequence analysis of GS mRNA from A. pallida based on polymerase chain reaction (PCR) technology that employed a combination of degenerate and A. pallida-specific primers. The sequenced cDNA approximates 1620 nucleotides and is characterized by an open reading frame of 1107 nucleotides that encodes a protein of 369 amino acid residues. Comparisons of the deduced sea anemone GS protein to a wide range of species demonstrated greatest amino acid sequence identity to sea urchin GS (66%) and least identity to green algae GS (51%). The sequenced cDNA can be used in future research to study GS gene expression in A. pallida.