Category:Team Blue-B

In figure 4, RNAP binding to the promoters in phage phi 29 is monitored in the presence of proteins p4 and p6 with or without mutations at the C-end. The gel shows the inability of a stable p4-p6 complex to form in order to properly repress transcription (ie. blocking the binding of RNAP to the A2c promoter), due to a mutation at the C-end of the p4 protein.

Figure 3. Competitive EMSA with increasing amounts of [p4] and [p6] incubated in each lane to observe the p4-p6 nucleoprotein complex formation at the late A3 promoter between positions -58 to -104. P4 by itself binds downstream of -58 position; P6 by itself binds throughout the -58 to -104 position; suggesting that the p4 protein allows specific sites for the complex to form.

Figure 4 displays 3 plasmids and a control to be tested against 2 mutated phages missing either gpG and gpGT or just gpGT, and a wildtype phage. From protein expression, it was concluded that not only gpG is required for tail assembly, but also that the G of gpGT is also integral in successful tail assembly and phage growth.

Figure 2B. A DNase I footprinting assay with both the wild type and mutant was run to observe the p6 and p4 complexes with a DNA fragment containing promoters A3, A2b, and A2c. Calles et al. incubated each lane with an increasing concentration of p6 or p4 and observed the footprints, or areas where the DNase fails to cut because of complex bounded onto the DNA. Mutant p4 proteins lead to a decrease in repression due to the failure of the p4-p6 nucleocomplex protein to form, showing the importance of the p4 protein in transcriptional repression. The presence of p4 protein increases the affinity of the p6 protein to bind, which would repress transcription.

The wildtype gel in figure 1 supports transcriptional activity under normal conditions, and it is contrasted and supported by the change in transcription activity recorded in neighboring gels.

Figure 1 displays the mutations of protein p4 and their effects on forming the repression complex between proteins p4 and p6 that represses early transcription in Bacillus subtilis phage phi 29. These mutations disallow the formation of a stable complex, hence the repressor complex cannot be formed between proteins p4 and p6 to completely halt early transcription and switch to late transcription.