Bacteriophage T4 short tail fibers are the product of gene 12

The baseplate of wild-type T4 phage carries a small number (probably 6) of short tail fibers in addition to the well known long tail fibers and tail pins. Short tail fibers are missing from defective T4 particles (12⁻ particles) lacking only the product of T4 gene 12 and are restored by in vitro complementation. Phage are neutralized by an antiserum swept with 12⁻ particles; that neutralizing activity is in turn quantitatively blocked exclusively by soluble 12P or by particles that carry 12P. 12⁻ particle-swept antibody aggregates phage through their short tail fibers. It can be concluded that these fibers are the product of gene 12.Antibody blocking experiments and in vitro complementation confirm the pleiotropic role of gene 57 product in phage T4 morphogenesis: 57⁻ particles are deficient in 12P as well as in long tail fibers.