More Than One Type of Transglutaminase in Invertebrates? A Second Type of Transglutaminase is Involved in Shrimp Coagulation

• Main Authors: Meng-Yi Chen, 陳夢怡
• Other Authors: Yen-Ling Song
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/06983834919170909951

碩士 === 國立臺灣大學 === 動物學研究研究所 === 93 === Coagulation (clot formation) can form a physical barrier to prevent the loss of body fluid and dissemination of microbes into the hemocoel after injury or infection. Its quickness and efficiency is essential for survival of invertebrates that relay solely on the innate immunity. Though the components and activation of coagulation system is diversified in the invertebrates, transglutaminase (TG) (EC 2.3.2.13) is the only conserved member throughout the known species. TG catalyzes intermolecular or intramolecular ε-(γ-glutamyl) lysine bond formation, resulting in protein polymerization. Physiologically, they are known for the roles in blood coagulation and post-translational protein modification. In the present study, we cloned a TG from shrimp (Penaeus monodon) hemocyte cDNA. It was assigned shrimp transglutaminase II (STG II). The TG cDNA consists of a coding region of 2,274 bp. The deduced protein has 757 amino acid residues, a calculated molecular mass of 85,000 Da and an isoelectric point of 5.48. RT-PCR results showed a high level of STG II expression in hemocytes, but not in hepatopancreas, differently from STG I. Neighbor Joining analysis indicates the genetic distance between STG II and STG I is much larger than that between STG II and TG of kuruma shrimp (Marsupenaeus japonicus). These evidences suggest at least two types of shrimp TG encoded from different chromosomal loci. The recombinant STG II was expressed using insect-baculovirus expression system. It showed polymerization activity on clottable proteins extracted from shrimp plasma. Under TEM observation, the polymerized chain resembles structurally the reacting products from shrimp hemocyte lysate supernatants on their plasma. Conclusively, STG II is characterized to be a hemocytic TG and involved in coagulation.