FIG. 4.

The C-terminal domains of T and RI are the determinants of LIN. (A) ^ssPhoAΦRI_CTD is necessary and sufficient for LIN. CQ21(λkanΔ(SR)) cells carrying the indicated plasmids were induced at time zero, and culture turbidity was monitored as a function of time: ⊠, pT4T; ▪, □, pT4T and pZA-RI; ○, •, pT4T and pZA-^ssPhoAΦRI_CTD; ▴, pT4T and pZA-RI_NTDΦPhoA; ⧫, pS105; ⋄, pS105 and pZA-RI; ▿, pS105 and pZA-^ssPhoAΦRI_CTD. To demonstrate premature triggering, KCN was added to two cultures (pT4T and pZA-RI, □; and pT4T and pZA-^ssPhoAΦRI_CTD, ○) at the time indicated by the solid arrow. (B) Phage accumulation during ^ssPhoAΦRI_CTD-mediated LIN. CQ21(λ-t^his) carrying the indicated plasmids was induced at time zero, and culture turbidity (solid symbols) and phage accumulation (open symbols) were monitored as a function of time. ○, •, no plasmid; ⋄, ⧫, pZA-RI; □, ▪, pZA-^ssPhoAΦRI_CTD. (C) Periplasmic T_CTD interferes with LIN. CQ21(λkanΔ(SR)) cells carrying the indicated plasmids were induced at time zero, and culture turbidity was monitored as a function of time. •, pT4T; ○, pT4T and pZA-^ssPhoAΦT_CTD; □, pZA-^ssPhoAΦT_CTD; ▵, pT4TRI; ▿, pT4TRI and pZA-^ssPhoAΦT_CTD; ⋄, pT4TRI and pZA-T_CTD; ▴, pT4TRI and pZAT_TCD; ▾, pT4TRI and pZA- FtsI_TMDΦT_70-218; ▪, pT4TRI and pZA-T_TMDΦPhoA. (Inset) Detail for growth of cells carrying pT4T alone (•) and pT4T and pZA-^ssPhoAΦT_CTD (○). (D) Periplasmic T_CTD blocks LIN during T4 phage infections. CQ21 cells carrying either pZA32-luc (solid symbols) or pZA-^ssPhoAΦT_CTD (open symbols) were induced at time zero and were grown without infection (○, •) or infected at a multiplicity of infection of 10 with either T4D (□, ▪) or T4rI (▵,▴). In panels A, C, and D, CHCl₃ was added at the time indicated by the arrow.