Production of high mannose glycosylated proteins stored in the plastid of microalgae

A transformed microalga producing at least one protein harboring a “high mannose” pattern of glycosylation in the plastid of said transformed microalga, wherein

• 1) said transformed microalga has a Chloroplast Endoplasmic Reticulum (CER);
• 2) said microalga has been transformed with a nucleic acid sequence operatively linked to a promoter, said nucleic acid sequence encoding an amino acid sequence comprising:
• (i) An amino-terminal bipartite topogenic signal (BTS) sequence composed of at least a signal peptide followed by a transit peptide;
• and
• (ii) The sequence of said protein;
• 3) the xylosyltransferases and fucosyltransferases of said microalga have not been inactivated;
• 4) The N-acetylglycosyltransferase I of said microalga has not been inactivated, preferably the N-acetylglycosyltranferases II, III, IV, V and VI, mannosidase II and glycosyltransferases of said microalga have not been inactivated.

A method for producing at least one protein harboring a “high mannose” pattern of glycosylation in the plastid of a transformed microalga producing at least one protein harboring a “high mannose” pattern of glycosylation in the plastid of said transformed microalga, wherein

• 1) said transformed microalga has a Chloroplast Endoplasmic Reticulum (CER);
• 2) said microalga has been transformed with a nucleic acid sequence operatively linked to a promoter, said nucleic acid sequence encoding an amino acid sequence comprising:
• (i) An amino-terminal bipartite topogenic signal (BTS) sequence composed of at least a signal peptide followed by a transit peptide;
• and
• (ii) The sequence of said protein;
• 3) the xylosyltransferases and fucosyltransferases of said microalga have not been inactivated;
• 4) the N-acetylglycosyltransferase I of said microalga has not been inactivated, preferably the N-acetylglycosyltranferases II, III, IV, V and VI, mannosidase II and glycosyltransferases of said microalga have not been inactivated;
• wherein said method comprises the steps of:
• 1) culturing said transformed microalga;
• 2) harvesting the plastid of said transformed microalga;
• and
• 3) purifying said protein from said plastid.