Secretion of Pem-CMG, a peptide in the CHH/MIH/GIH Family of Penaeus monodon, in Pichia pastoris is directed by secretion signal of the α-mating factor from Saccharomyces cerevisiae

The CHH/MIH/GIH peptide family of black tiger prawn (Paneaus monodon) is important in shrimp reproduction and growth enhancement. In this study, the cDNA that encodes the complete peptide that is related to the CHH/MIH/GIH family (so-called, Pem-CMG) in the eyestalk of P. monodon was successfully expressed in a methylotrophic yeast Pichia pastoris under the control of an alcohol oxidase promoter. In order to obtain the secreted Pem-CMG, a secretion signal of either the Saccharomyces cerevisiae α-factor or Pem-CMG was employed. The results demonstrated that αPem-CMG, either with (α2EACMG) or without (αCMG) the Glu-Ala repeats, was secreted into the medium, while Pem-CMG with its own secretion signal failed to be secreted. The total protein amount that was secreted from the transformant that contained either α2EACMG or αCMG was approximately 60 mg/l and 150 mg/l, respectively. The N-terminus of the Pem-CMG peptide of both α2EACMG and αCMG was correctly processed. This produced the mature Pem-CMG peptide.