Fig. 1. gp105, an early and highly expressed phage protein, forms a shell around viral DNA during phage infection.

(A) N-terminal fusion of gp105 to GFP (GFP-gp105; green) is diffuse in uninfected P. chlororaphis cells (top) and assembles a shell that encloses the phage DNA at 45 min postinfection (mpi) with phage 201ϕ2-1 (bottom). Cell membranes were stained with FM 4–64 (red), and DNA was stained with DAPI (blue). (B) Fluorescence recovery after photobleaching (FRAP) of the GFP-gp105 shell at 45 mpi. The bleached area of the shell generated at time 0 min does not recover over the course of 16 min. Heat maps show GFP intensity corresponding to the images above. (C and D) Time-lapse imaging (measured in minutes postinfection or seconds) of GFP-gp105 in the presence of mCherry-tagged (red) (C) wild-type PhuZ and (D) mutant PhuZ^D190A. (C) As indicated by arrowheads, the shell moves to the midcell and rotates (in this case, clockwise) during phage infection in the presence of wild-type PhuZ. See also movies S1 and S3. (D) In the presence of PhuZ^D190A, the shell remains at the cell pole throughout the experiment and does not rotate. A lack of rotation is sometimes observed in the presence of wild-type PhuZ for larger gp105 shells such as that shown in (B). Dashed circles indicate the border of the cells. (E) Static images of infected host cells expressing GFP-gp105 together with either wild-type mCherry-PhuZ or mutant mCherry-PhuZ^D190A at 60 mpi. Phage DNA was stained blue with DAPI. (A to E) Scale bars, 0.5 µm. (F) Protein mass spectrometry analysis of phage-infected cells showing putative nonstructural phage proteins until 60 mpi. The gp105 protein (green line) is the most highly expressed phage protein. (See table S1.)