Bacteriophage lambda surface display of a bacterial biotin acceptor domainreveals the minimal peptide size required for biotinylation

Phage display is a powerful technique for identifying specific ligands to a given target. In this work random peptides derived from the biotin accepti ng domain of the Klebsiella pneumoniae oxaloacetate decarboxylase were disp layed on bacteriophage lambda heads to determine the minimal sequence lengt h that is necessary to effect biotinylation in vivo. Phages with a function al biotinylation domain were identified after affinity purification with im mobilised avidin. All biotinylated phages isolated this may were found to h ave a sequence of 66 amino acids from the parental protein in common. This minimal biotinylation domain is fully functional as a biotin acceptor and m ore resistant to proteolytic attack compared to domains of larger size deri ved from the same protein. The data present the first example of a posttran slational protein modification analysed in a phage display system. Moreover , a biotin domain of reduced size and improved stability was identified, th at should be superior to the larger parental protein as a tag to generate b iotinytated fusion proteins. (C) 1998 Federation of European Biochemical So cieties.