Cloning and identification of four Mu-type glutathione S-transferases from the giant freshwater prawn Macrobrachium rosenbergii.

ABSTRACT

Glutathione S-transferases (GSTs) are essential components of the cellular detoxification system because of their capability to protect organisms against the toxicity of reactive oxygen species (ROSs). Four different GSTs (MrMuGST1-MrMuGST4) showing similarities with Mu-type GSTs were cloned from the hepatopancreas of Macrobrachium rosenbergii. These four GSTs have 219, 216, 218 and 219 amino acids in length, respectively. MrMuGST1-MrMuGST4 proteins all have a G-site in the N-terminus and an H-site in the C-terminus. Phylogenetic analysis reveals that four Mu-type GSTs are classified into two different clades (MrMuGST2 one clade; MrMuGST1, MrMuGST3 and MrMuGST4 other clades). Nonetheless, no site under positive selection was detected but rapid evolution was found in the few of MuGST genes. Reverse transcription-polymerase chain reaction (RT-PCR) results showed that MrMuGST1 and MrMuGST2 transcripts were expressed in all detected tissues, however, MrMuGST3 and MrMuGST4 were just mainly expressed in hepatopancreas and intestines. Quantitative RT-PCR analysis showed that MrMuGST1 and MrMuGST2 were down-regulated upon Vibrio anguillarum challenge, whereas MrMuGST3 and MrMuGST4 were quickly up-regulated 2 h after the Vibrio challenge. Our results imply that different Mu-type GSTs may respond to Vibrio challenge with different manners.