title: Purification of phage display-modified bacteriophage T4 by affinity chromatography.
abstract: BACKGROUND
  Affinity chromatography is one of the most efficient protein purification strategies. This technique comprises a one-step procedure with a purification level in the order of several thousand-fold, adaptable for various proteins, differentiated in their size, shape, charge, and other properties. The aim of this work was to verify the possibility of applying affinity chromatography in bacteriophage purification, with the perspective of therapeutic purposes. T4 is a large, icosahedral phage that may serve as an efficient display platform for foreign peptides or proteins. Here we propose a new method of T4 phage purification by affinity chromatography after its modification with affinity tags (GST and Histag) by in vivo phage display. As any permanent introduction of extraneous DNA into a phage genome is strongly unfavourable for medical purposes, integration of foreign motifs with the phage genome was not applied. The phage was propagated in bacteria expressing fusions of the phage protein Hoc with affinity tags from bacterial plasmids, independently from the phage expression system.
  
  
  RESULTS
  Elution profiles of phages modified with the specific affinity motifs (compared to non-specific phages) document their binding to the affinity resins and effective elution with standard competitive agents. Non-specific binding was also observed, but was 102-105 times weaker than the specific one. GST-modified bacteriophages were also effectively released from glutathione Sepharose by proteolytic cleavage. The possibility of proteolytic release was designed at the stage of expression vector construction. Decrease in LPS content in phage preparations was dependent on the washing intensity; intensive washing resulted in preparations of 11-40 EU/ml.
  
  
  CONCLUSIONS
  Affinity tags can be successfully incorporated into the T4 phage capsid by the in vivo phage display technique and they strongly elevate bacteriophage affinity to a specific resin. Affinity chromatography can be considered as a new phage purification method, appropriate for further investigations and development.
authors.affiliation: Bacteriophage Laboratory, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R.Weigla 12, Wroclaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Oślizło
authors.forename: Paulina
authors.initials: P
authors.lastname: Miernikiewicz
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Piotrowicz
authors.forename: Barbara
authors.initials: B
authors.lastname: Owczarek
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kopciuch
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Figura
authors.forename: Krystyna
authors.initials: K
authors.lastname: Dąbrowska
mesh_terms: D017122:Bacteriophage T4 / Q000302:isolation & purification* / Q000378:metabolism; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism; D002846:Chromatography, Affinity / Q000379:methods*; D003001:Cloning, Molecular; D005978:Glutathione / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism; D019151:Peptide Library; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; C108525:HOC protein, T4 phage; C471213:His-His-His-His-His-His; D009842:Oligopeptides; D019151:Peptide Library; D011993:Recombinant Fusion Proteins; D006639:Histidine; D005978:Glutathione