Potential role of single hotdog fold thioesterase in the antiviral response of Fenneropenaeus chinensis.

Thioesterase superfamily member 2 (Them2) is a single hotdog fold thioesterase domain-containing protein. Its biological function is not well known. Recently, a hotdog fold thioesterase (FcThem) was cloned for the first time from the Chinese white shrimp. The full length of FcThem is 748bp. It encodes a protein with 142 amino acids with a predicted molecular mass of 14.79kDa and an isoelectric point of 8.76. No signal peptide was predicted. Multiple alignment of FcThem with other Them2 proteins suggested a conserved HGG motif. Phylogenetic analysis showed that FcThem were clustered with vertebrate Them2 protein into one group. The RT-PCR results showed that FcThem was a widely distributed gene and could be detected in the hemocytes, heart, hepatopancreas, gills, stomach, intestines, and ovaries of unchallenged shrimps. In hemocytes, its transcript was upregulated 24h post WSSV challenge. In the gills, the FcThem went up at a 6h WSSV challenge. FcThem expression in the ovaries was also affected by the WSSV and was increased after the 2h WSSV challenge, reaching the highest level at 6h. Our results show that FcThem probably has roles in the innate immunity system of shrimps and investigations will be carried out to explore this finding further.