Molecular cloning and characterization of glutamine synthetase, a tegumental protein from Schistosoma japonicum

• Published in: Parasitology research (1987) 2012-12, Vol.111 (6), p.2367-2376
• Main Authors: Qiu, Chunhui, Hong, Yang, Cao, Yan, Wang, Fei, Fu, Zhiqiang, Shi, Yaojun, Wei, Meimei, Liu, Shengfa, Lin, Jiaojiao
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Blotting, Western; Catalytic Domain; Cloning; Cloning, Molecular; Computational Biology; Enzyme Stability; Escherichia coli; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation; General aspects; General aspects and techniques. Study of several systematic groups. Models; Genetic aspects; Glutamate-Ammonia Ligase - chemistry; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; Glutamine; Hydrogen-Ion Concentration; Immunology; Invertebrates; Ligases; Medical Microbiology; Microbiology; Microscopy, Fluorescence; Models, Molecular; Molecular Sequence Data; Molecular Weight; Original Paper; Recombinant proteins; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; RNA; Schistosoma japonicum; Schistosoma japonicum - enzymology; Schistosoma japonicum - genetics; Sequence Alignment; Temperature
• ISSN: 0932-0113; 1432-1955
• DOI: 10.1007/s00436-012-3092-6

Glutamine synthetase catalyzes the synthesis of glutamine, providing nitrogen for the production of purines, pyrimidines, amino acids, and other compounds required in many pivotal cellular events. Herein, a full-length cDNA encoding Schistosoma japonicum glutamine synthetase (SjGS) was isolated from 21-day schistosomes. The entire open reading frame of SjGS contains a 1,095-bp coding region corresponding to 364 amino acids with a calculated molecular weight of 40.7 kDa. NCBIP blast shows that the putative amino acid of SjGS contains a classic β-grasp domain and a catalytic domain of glutamine synthetase. The relative mRNA expression of SjGS was evaluated in 7-, 13-, 21-, 28-, 35-, and 42-day worms of S. japonicum in the final host and higher expression at day 21, and 42 worms were observed. This protein was also detected in worm extracts using Western blot. Immunofluorescence studies indicated that the SjGS protein was mainly distributed on tegument and parenchyma in 28-day adult worms. The recombinant glutamine synthetase with a molecular weight of 45 kDa was expressed in Escherichia coli and purified in its active form. The enzyme activity of the recombinant protein was 3.30 ± 0.67 U.μg-1. The enzyme activity was highly stable over a wide range of pH (6–9) and temperature (25–40 °C) under physiological conditions. The transcription of SjGS was upregulated in praziquantel-treated worms at 2-, 4-, and 24-h posttreatment compared with the untreated control. As a first step towards the clarification of the role of glutamine synthetase in schistosome species, we have cloned and characterized cDNAs encoding SjGS in S. japonicum , and the data presented suggest that SjGS is an important molecule in the development of the schistosome.