[The beta-helical domain of bacteriophage T4 controls the folding of the fragment of long tail fibers in a chimeric protein].

The key stage of the infection of the Escherichia coli cell with bacteriophage T4, the binding to the surface of the host cell, is determined by the specificity of the long tail fiber proteins of the phage, in particular, gp37. The assembly and oligomerization of this protein under natural conditions requires the participation of at least two additional protein factors, gp57A and gp38, which strongly hinders the production of the recombinant form of gp37. To overcome this problem, a modern protein engineering strategy was used, which involves the construction of a chimeric protein containing a carrier protein that drives the correct folding of the target protein. For this purpose, the trimeric beta-helical domain of another protein of phage T4, gp5, was used. It was shown that this domain, represented as a rigid trimeric polypeptide prism, has properties favorable for use as a protein carrier. A fragment of protein gp37 containing five pentapeptides repeats, Gly-X-His-X-His, which determine the binding to the receptors on the bacterial cell surface, was fused in a continuous reading frame to the C-terminus of the domain of gp5. The resulting chimeric protein forms a trimer that has the native conformation of gp37 and exhibits biological activity.