Identification and expression characterization of pepsinogen A in orange‐spotted grouper, Epinephelus coioides

Abstract

To understand the molecular mechanisms associated with digestive physiology of the stomach of orange-spotted grouper Epinephelus coioides, a cDNA library was constructed and 331 expressed sequence tags (EST) were generated and annotated. About 37Á17% of 226 identified ESTs were possibly related to digestive enzymes. Two type-A pepsinogens differing in putative isoelectric point were identified and characterized for the first time in E. coioides. The complete cDNAs were 1312 and 1314 bp in length, and the deduced polypeptide sequences comprised 376 and 377 amino acids, respectively. Both genes consisted of eight introns of various lengths. Alignment and a phylogenetic tree based on the amino acid sequences of pepsins indicated that pepsin A1 and A2 could be classified into two different subtypes. Northern blot hybridization showed that there were two forms of transcripts for pepsinogen A1 and three for pepsinogen A2. Reverse transcription-PCR (RT-PCR) followed by Southern blot analysis revealed that two type-A pepsinogen mRNAs were present in the adult stomach tissue, and pepsinogen A2 was also detectable in the mid-intestine. Furthermore, pepsinogen A1 transcript was first detected at 29 days post-hatching, while pepsinogen A2 was continuously expressed through hatching to adult fish. These results imply that transcriptional regulation and physiological function of the two type-A pepsinogens may be different.

Study on Pepsinogens and Pepsins from Snakehead (Channa argus)

“…Quite possibly, because of the steric structure of the protein, the p I value may not be in complete accordance with its performance under chromatographic pH conditions (pH 7.0). p I values of other fish, such as three pepsinogens from Pacific bluefin tuna (5.69, 4.95, and 4.66) and pepsinogens A1 and A2 from orange-spotted grouper (4.41 and 5.17) , have been reported, whereas all of these p I values were deduced from amino acid sequence analysis based on molecular cloning. Compared with these, the p I values of snakehead pepsinogens were relatively lower.…”

Recurrent gene loss correlates with the evolution of stomach phenotypes in gnathostome history

“…In fishes, a distinct nomenclature is currently used and three pepsinogen gene families have been described: Pgc, Pga1 and Pga2 [35][36][37][38]. We began by determining the repertoire of Pga, Pgf and Cym in tetrapods.…”

“…Tetrapod aspartic proteases expressed almost uniquely in the stomach include Pga, Pgf, Pgc, Pgb and Cym [12,[32][33][34]. In fishes, a distinct nomenclature is currently used and three pepsinogen gene families have been described: Pgc, Pga1 and Pga2 [35][36][37][38]. We began by determining the repertoire of Pga, Pgf and Cym in tetrapods.…”

Purification and characterization of pepsinogens and pepsins from the stomach of rice field eel (Monopterus albus Zuiew)

“…The possibility that because of the steric structure of the protein, the pI value may not be in complete accordance with the performance of PG1 under chromatographic pH conditions was ascribed. On the other hand, pI values of three PGs from Pacific bluefin tuna (5.69, 4.95, 4.66;Tanji et al 2009), pepsinogen A1 and A2 from orange-spotted grouper (4.41, 5.17;Feng et al 2008), which were deduced from nucleotide sequences of cDNAs, have also been reported.…”