title: Dissection of an old protein reveals a novel application: domain D of Staphylococcus aureus Protein A (sSpAD) as a secretion--tag.
abstract: BACKGROUND
  Escherichia coli as a frequently utilized host organism for recombinant protein production offers different cellular locations with distinct qualities. The periplasmic space is often favored for the production of complex proteins due to enhanced disulfide bond formation, increased target product stability and simplified downstream processing. To direct proteins to the periplasmic space rather small proteinaceus tags that can be used for affinity purification would be advantageous.
  
  
  RESULTS
  We discovered that domain D of the Staphylococcus aureus protein A was sufficient for the secretion of various target proteins into the periplasmic space of E. coli. Our experiments indicated the Sec pathway as the mode of secretion, although N-terminal processing was not observed. Furthermore, the solubility of recombinant fusion proteins was improved for proteins prone to aggregation.The tag allowed a straightforward affinity purification of recombinant fusion protein via an IgG column, which was exemplified for the target protein human superoxide dismutase 1 (SOD).
  
  
  CONCLUSIONS
  In this work we present a new secretion tag that combines several advantages for the production of recombinant proteins in E. coli. Domain D of S. aureus protein A protects the protein of interest against N-terminal degradation, increases target protein solubility and enables a straight-forward purification of the recombinant protein using of IgG columns.
authors.affiliation: Austrian Center of Industrial Biotechnology (ACIB), TU Graz, Petersgasse 14, A-8010 Graz, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Heel
authors.forename: Michael
authors.initials: M
authors.lastname: Paal
authors.forename: Rainer
authors.initials: R
authors.lastname: Schneider
authors.forename: Bernhard
authors.initials: B
authors.lastname: Auer
mesh_terms: D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D019897:Periplasm / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism*; D012995:Solubility; D013205:Staphylococcal Protein A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013211:Staphylococcus aureus / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1
chemical_list: D011993:Recombinant Fusion Proteins; C000606290:SOD1 protein, human; D013205:Staphylococcal Protein A; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1