title: A cost-effective ELP-intein coupling system for recombinant protein purification from plant production platform.
abstract: BACKGROUND
  Plant bioreactor offers an efficient and economical system for large-scale production of recombinant proteins. However, high cost and difficulty in scaling-up of downstream purification of the target protein, particularly the common involvement of affinity chromatography and protease in the purification process, has hampered its industrial scale application, therefore a cost-effective and easily scale-up purification method is highly desirable for further development of plant bioreactor.
  
  
  RESULTS
  To tackle this problem, we investigated the ELP-intein coupling system for purification of recombinant proteins expressed in transgenic plants using a plant lectin (PAL) with anti-tumor bioactivity as example target protein and rice seeds as production platform. Results showed that ELP-intein-PAL (EiP) fusion protein formed novel irregular ER-derived protein bodies in endosperm cells by retention of endogenous prolamins. The fusion protein was partially self-cleaved in vivo, but only self-cleaved PAL protein was detected in total seed protein sample and deposited in protein storage vacuoles (PSV). The in vivo uncleaved EiP protein was accumulated up to 2-4.2% of the total seed protein. The target PAL protein could be purified by the ELP-intein system efficiently without using complicated instruments and expensive chemicals, and the yield of pure PAL protein by the current method was up to 1.1 mg/g total seed protein.
  
  
  CONCLUSIONS
  This study successfully demonstrated the purification of an example recombinant protein from rice seeds by the ELP-intein system. The whole purification procedure can be easily scaled up for industrial production, providing the first evidence on applying the ELP-intein coupling system to achieve cost-effective purification of recombinant proteins expressed in plant bioreactors and its possible application in industry.
authors.affiliation: School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Li
authors.initials: L
authors.lastname: Tian
authors.forename: Samuel S M
authors.initials: SS
authors.lastname: Sun
mesh_terms: D047668:Inteins / Q000235:genetics*; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D037121:Plant Lectins / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D055314:Seed Storage Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000378:metabolism
chemical_list: D010455:Peptides; D037121:Plant Lectins; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D055314:Seed Storage Proteins