Rhizosecretion of The Recombinant Antimicrobial Peptide Ranalexin from Transgenic Tobacco Hairy Roots

Rhizosecretion of functional recombinant proteins from in vitro cultured roots into the hydroponic medium offers an attractive technology to simplify down-stream purification procedures. Aim of the present study was the production and secretion of the antimicrobial peptide (AMP) ranalexin from Nicotiana tabacum hairy roots which were transformed by agroinfection. A His-tagged ranalexin was expressed under the control of CaMV 35S promoter and directed into the plant secretion pathway by fusing its N terminus to the ER signal peptide of calreticulin. The maximal accumulation of ranalexin in hairy root tissue after 20-25 days of culture accounted for about 3.36% of the total soluble protein. Secreted ranalexin reached a concentration of 0.28 mg/L in the medium on day 25. Extracellular ranalexin level could be increased to 1.64 mg/L by the addition of polyvinylpyrrolidone to the culture medium. The secreted ranalexin is active against Gram positive and Gram negative bacteria including strains which are multiresistant against antibiotics, such as methicillin-resistant Staphylococcus aureus MRSA, vancomycin-resistant Enterococcus VRE, Streptococcus pyogenes, Escherichia coli, Acinetobacter baumanii as well as clinical MRSA isolates. Our results demonstrate the usefulness of plant tissue cultures especially tobacco hairy roots as an alternative production system of ranalexin and other antimicrobial peptides. Received date: 01/07/2015 Accepted date: 29/07/2015 Published date: 31/07/2015 *For Correspondence Dr. Michael Wink, Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany, Tel: 06221 54 6032; E-mail: [email protected]