Berget, PB and King, J. (1978) Virology, 86(2), 312-328

Antigenic gene products of bacteriophage T4 baseplates


Antibodies raised against isolated T4 precursor baseplates exponentially inactivated T4 phage. The target antigens of the killing antibody were different from the targets of serum raised against complete phage particles. To determine which of the fourteen species of baseplate structural proteins represented the target antigens, we examined cells infected with mutants defective in baseplate assembly. The major target antigen was associated with precursors of the outer arms of the mature baseplate. A candidate for the antigen was the gene 11 tailspike protein. Serum-blocking experiments with defective phage particles lacking the gene 11 protein indicated that it was the target of 85% of the neutralizing antibody in the serum. The remaining 15% of the neutralizing antibody was directed against the gene 12 protein, which forms the short baseplate fibers (Kells and Haselkorn, 1974). Cells infected with temperature-sensitive mutants in gene 11 had significantly decreased levels of the target antigen, supporting its identification as the product of gene 11. Surprisingly, cells infected with amber mutants at three different sites in gene 11 all accumulated normal levels of the target antigens, suggesting that the gene 11 amber fragments are stable and fully antigenic. The gene 11 tailspike protein complexes with the gene 10 protein in the first reaction in baseplate arm formation and is present in all subsequent intermediates in baseplate assembly. Therefore, antibody against the gene 11 product provides an assay for the purificatin of each of he intermediate protein complexes in baseplate morphogenesis.

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