Editing Phage display (section)

{{Short description|Biological technique to evolve proteins using bacteriophages}}
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{{Technical|date=October 2018}}
[[File:Phage display.png|right|thumb|400px|Phage display cycle. 1) fusion proteins for a viral coat protein + the gene to be evolved (typically an antibody fragment) are expressed in bacteriophage. 2) the library of phage are washed over an immobilised target. 3) the remaining high-affinity binders are used to infect bacteria. 4) the genes encoding the high-affinity binders are isolated. 5) those genes may have random mutations introduced and used to perform another round of evolution. The selection and amplification steps can be performed multiple times at greater stringency to isolate higher-affinity binders.]]
'''Phage display''' is a laboratory technique for the study of [[Protein–protein interaction|protein–protein]], [[protein]]–[[peptide]], and protein–[[DNA]] interactions that uses [[bacteriophage]]s ([[viruses]] that infect [[bacteria]]) to connect proteins with the [[genetic information]] that [[code|encodes]] them.<ref name="Smith_1985">{{cite journal | author = Smith GP | title = Filamentous fusion phage: novel expression vectors that display cloned antigens on the virion surface | journal = Science | volume = 228 | issue = 4705 | pages = 1315–7 |date=June 1985 | pmid = 4001944 | doi = 10.1126/science.4001944 |bibcode = 1985Sci...228.1315S }}</ref> In this technique, a gene encoding a protein of interest is inserted into a phage [[viral coat protein|coat protein]] gene, causing the phage to "display" the protein on its outside while containing the gene for the protein on its inside, resulting in a connection between [[genotype]] and [[phenotype]]. The proteins that the phages are displaying can then be screened against other proteins, peptides or DNA sequences, in order to detect interaction between the displayed protein and those of other molecules. In this way, large [[protein fragment library|libraries of proteins]] can be screened and [[amplification (molecular biology)|amplified]] in a process called ''[[in vitro]]'' selection, which is analogous to [[natural selection]].

The most common bacteriophages used in phage display are [[M13 bacteriophage|M13]] and [[Filamentous bacteriophage fd|fd]] [[filamentous phage]],<ref name="pmid11848876">{{cite journal |vauthors=Smith GP, Petrenko VA | title = Phage Display | journal = Chem. Rev. | volume = 97 | issue = 2 | pages = 391–410 |date=April 1997 | pmid = 11848876 | doi = 10.1021/cr960065d  }}</ref><ref name="pmid16277371">{{cite journal |vauthors=Kehoe JW, Kay BK | title = Filamentous phage display in the new millennium | journal = Chem. Rev. | volume = 105 | issue = 11 | pages = 4056–72 |date=November 2005 | pmid = 16277371 | doi = 10.1021/cr000261r }}</ref> though [[Enterobacteria phage T4|T4]],<ref name="Malys_2002">{{cite journal |vauthors=Malys N, Chang DY, Baumann RG, Xie D, Black LW | title = A bipartite bacteriophage T4 SOC and HOC randomized peptide display library: detection and analysis of phage T4 terminase (gp17) and late sigma factor (gp55) interaction |journal = J Mol Biol |volume = 319 | issue = 2 | pages = 289–304 | year = 2002 | doi =10.1016/S0022-2836(02)00298-X | pmid = 12051907 }}</ref> [[T7 phage|T7]], and [[Lambda phage|λ]] phage have also been used.