DnaA boxes

The oriC locus consists of a unique 245-bp sequence which contains a number of elements as shown in Fig. 16-15. These include four 9-bp segments called DnaA boxes which enable the oriC sequence to recognize and bind DnaA. Three 13-bp AT-rich segments at one end of oriC allow the DNA to open up during the process of initiation and provide an entry point for DnaB and DnaC. The oriC region and its immediate vicinity also contain numerous GATC sites which can be methylated. For simplicity they are not shown in Fig. 16-15. They have a role in preventing re-initiation of replication at oriC before the appropriate time in the cell cycle. 

Fig. 5 SPR analysis of E. coli DnaA protein interaction with DNA containing one DnaA box. 12 RU of 21mer DNA was immobilized on an SA chip. The protein was injected at concentrations of 0.39, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50, and 100 nM at a flow rate of 100 jjilmin-1. The association phase (130 s) was followed by 120 s dissociation phase, a The experimental data (rough lines) and response curves simulation based on evaluated rate constants (smooth lines), b Scatchard equilibrium analysis for the six highest concentrations of DnaA from a...

Figure 27-19 Hypothetical scheme for initiation of bidirectional replication in E. coli. The closed boxes R1 through R5 represent the 9-residue recognition sequences for the E. coli dnaA protein. The open boxes 1, 2, and 3 represent the three 13-residue repeats, possible sites for binding of the dnaB-dnaC protein complex. From McMacken et al.m Redrawn in simplified form.

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