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Appl Microbiol Biotechnol (2009) 85:155164 DOI 10.1007/s00253-009-2130-5
APPLIED MICROBIAL AND CELL PHYSIOLOGY
Dextran sodium sulfate enhances secretion of recombinant human transferrin in Schizosaccharomyces pombe
Hiroyuki Mukaiyama & Yuko Giga-Hama &
Hideki Tohda & Kaoru Takegawa
Received: 26 May 2009 /Revised: 4 July 2009 /Accepted: 6 July 2009 /Published online: 23 July 2009 # Springer-Verlag 2009
Abstract The effect of medium supplementation on heterologous production of human serum transferrin (hTF) in the fission yeast Schizosaccharomyces pombe has been investigated. The productivity of recombinant hTF was low in wild-type S. pombe cells. To overcome this impediment, culture media supplements were screened for their ability to improve secretion of hTF. Casamino acids (CAA), which have been reported to increase heterologous protein productivity in Pichia pastoris, improved the secretion hTF by more than fourfold. An anion surfactant deoxycholate or polyethylene glycol also improved the secretion hTF. Interestingly, dextran sodium sulfate (DSS), a poly-anion surfactant, was found to enhance production of secreted hTF better than any other supplement tested. Addition of DSS in the presence of 2% CAA exhibited a synergistic effect on increasing hTF secretion, resulting in an increase of about sevenfold relative to conventional conditions. Cell growth was not found to be affected by the addition of DSS or CAA. DSS may act as a surfactant and may also facilitate the anchoring of liposomes, and these properties may contribute to efficient secretion or exocytosis through the plasma membrane.
Keywords Heterologous protein production .
Schizosaccharomyces pombe . Human transferrin . Secretion
Introduction
Transferrins are a homologous family of Fe3+-binding proteins that include serum transferrin, ovotransferrin, lactoferrin, and melanotransferrin (Aisen and Listowsky 1980; Bullen et al. 2000). They are monomeric glycoproteins of approximately 80 kDa containing two domains (N-lobe and C-lobe) that play an important role in iron metabolism due to their ability to bind iron (Baker et al. 2003). Serum transferrins play a role in iron transport. Lactoferrins are found in milk, tears, and other bodily secretions in numerous mammals. Ovotransferrins are found in avian egg white, and melanotransferrins are found on the surface of melanocytes (Bullen et al. 2000). Within the transferrin family, human serum transferrin (hTF), which is secreted as a 679-residue protein with 20 disulfide bonds and two N-glycan chains on the C-lobe, functions to transport...