Molecular cloning and functional analysis of a destabilase from Hirudinaria manillensis

Destabilases are i-type lysozymes with isopeptidase activity and antibacterial and thrombolytic functions. In recent years, destabliases have been identified in an increasing number of invertebrates. Hirudinaria manillensis belonging to the Annelida, as one of the origins of leeches used in traditional Chinese medicine, which has high medicinal value, there have been few reports on the H. manillensis destabliase. In this study, the cDNA sequence of Hmdestabilase was cloned from the salivary glands of H. manillensis. The 3D Structural analysis indicated that Hmdestabilase is similar to other i-type lysozymes in that it adopts an ellipsoidal shape and has a large cleft containing the lysozyme active site. The docking results of Hmdestabilase protein with N-acetylglucosamine trimer molecule have shown that the location and number of hydrogen bonds are one of the key factors for the interaction between the protein and its substrate. The Hmdestabilase fusion protein obtained through the prokaryotic expression system has lysozyme and isopeptidase activities. In addition, Changes in sodium ion concentration in the environment affect the lysozyme activity of Hmdestabilase fusion protein. The above bioinformatic analysis and enzymatic function studies have shown that Hmdestabilase belongs to the i-type lysozyme family. qPCR analysis revealed that blood feeding significantly increased the mRNA expression of Hmdestabilase in the salivary glands of H. manillensis,and successfully priming the innate immune system against harmful microorganisms ingested with food. This study is helpful to elucidate the innate immune response of H. manillensis and promote the artificial breeding of H. manillensis.