Tandem repeat strategy

The repeat gene family tandem repeats may increase both intra- and intermolecular recombination events, which result in gene or epitope amplification that is usually followed by sequence divergence. This could be another strategy of adaptation by the virus to keep pace with its evolving host. Because of its potentially large size and sequence diversity, the 540-bp repeat gene family will presumably play an important role. Based upon predicted properties, the 540-bp repeat proteins are believed to function differently than those of the cysteine-rich family. 

S. Goletz, B. Thiede, F.-G. Hanisch, M. Schultz, J. Peter-Katalinic, S. Muiller, O. Seitz, and U. Karsten, A sequencing strategy for the localization of O-glycosylation sites of MUC1 tandem repeats by PSD-MALDI mass spectrometry, Glycobiology, 7 (1997) 881-896. 

Figure 1 Strategy for cloning a peptide-coding sequence (CDS) as tandem repeats in the vector pET31b. The resulting fusion protein, comprising the ketosteroid isomerase (KSI), peptide repeats, and His-tag, is targeted to inclusion bodies. The fusion protein can be recovered and cleaved, in this case, with cyanogen bromide (CNBr) which acts at the methionine (M) residues allowing further separation of pure peptide from the other fusion components. The cleavage by CNBr results in a C-terminal homoserine lactone (hsl) on each peptide monomer.

Another strategy was pursued by Boons et al. who assembled a dec-apeptide partial sequence of the MUCl tandem repeat containing a Tn-antigen and prolonged this structure via an JV-terminal glycine with a T-cell epitope (from polio virus) in one linear synthesis on solid-phase. Finally, a... 

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