Cloning, expression, and sequence analysis of hydrazine synthase A-subunit (hzsA) functional gene from anammox bacteria

Anaerobic ammonia oxidation (anammox) is an efficient biological technology for nitrogen removal. Hydrazine synthase synthesizes the intermediate hydrazine as one of the key enzymes in the metabolism of anammox bacteria. The genomic DNA of anammox bacteria was extracted as a template. Sequence homology and phylogenetic tree analysis showed that the clone gene was closely related to the cloned hydrazine synthase A-subunit (hzsA) from an uncultured anaerobic ammonium-oxidizing bacterium. The full-length cDNA of the hzsA gene was 1331 bp and contained a 762 bp open reading frames (ORFs) encoding 253 amino acids protein. The deduced protein molecular weight was 28.00 kD and its theoretical isoelectric point was 7.62. Its instability coefficient was 31.91, which meant it was a stable protein, and its average hydrophilicity was -0.563, which meant it was a hydrophilic protein. And it was located in the cytoplasm without transmembrane domain and signal peptide. The secondary structure of hydrazine synthase A-subunit protein was composed of four types, the most of which was random coil, accounting for 52.96%, followed by extended strand (32.02%), beta turn (11.46%) and alpha helix (3.56%). The three-dimensional structure of the protein has been successfully modelled. There were no conserved domains in the protein.