Figure 23-2: Physical and genetic map of the genome of bacteriophage SPP1. The genome is presented in a circular form as found in the cell at early times after infection. The inner circle represents the base pair scale from 1 to 44,007 bp (3). Digestion of the DNA with EcoRI generates 16 fragments as indicated by lines and numbers in the thick bar circle. The packaging initiation sequence pacLCR (see section 'Morphogenesis') is shown as a black box indicated by a vertical arrow. The direction of packaging is shown by a dotted arrow. The white rhombi within the EcoRI-4 and EcoRI-3 fragments denote the oriL and oriR sequences, respectively (see section 'SPP1 DNA replication'). Segments of the genome dispensable for SPP1 multiplication are shown in white frames. The region coding for genes expressed early during infection is shown in dark grey and the region coding for late genes in light grey. The five early promoters (PE1-PE5; filled circles) are indicated by filled circles in the outer periphery of the map. Arrows show the direction of transcription by σA-RNAP and arrow heads the position of rho-independent transcription terminators. The late σA-RNAP promoters (PL1–PL5; open circles) and their transcripts are represented using the same symbols. The operons coding for genes involved in DNA replication, DNA packaging, and virion morphogenesis, as well as the regions of the genome not characterized yet are indicated in the outside. (for better image quality, click here for tif image, which may be quite large; may also require screen refreshing plus special software to view; or view larger tif in separate window)

Figure 23-1, Figure 23-2, Figure 23-3, Figure 23-4, Figure 23-5, Figure 23-6, Figure 23-7, Figure 23-8

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