FIG. 4.

Bound Dec protein stabilizes P22 virions. P22 c1⁻7 13⁻amH101 virions with (circles) and without (squares) saturating amounts of N-terminally histidine-tagged Dec protein were diluted in 10 mM TrisCl (pH = 7.4)-83 mM EDTA to a final concentration of 10⁸ virions/ml. After the indicated times at 50°C, aliquots were diluted in room-temperature TM, and titers were determined with Salmonella serovar Typhimurium strain DB7004. The two mutations were present in the phage genome to simplify growth and purification of the phage (6); they do not affect the virions produced in any way.