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. 2009 Jan 6;37(3):983–998. doi: 10.1093/nar/gkn1010

Figure 1.

Figure 1.

PvuII R-M system control region. (A) Genetic structure. The three genes specify a DNA methyltransferase (pvuIIM), restriction endonuclease (pvuIIR) and controller (activator/repressor, pvuIIC). The two transcription starts for pvuIICR are identified by rightward bent arrows: from the C-independent weak promoter (thin) and C-dependent strong promoter (thick) (25). The two pvuIIM promoters are also shown (leftward bent arrows). The four vertical rectangles represent the C-boxes, which are binding sites for C.PvuII. (B) The pvuIICR regulatory region sequence showing C-boxes and promoter elements. The nearly palindromic operators each contain a pair of C-boxes, designated as boxes 1AB or OL (operator left) and 2AB or OR (operator right). Conserved elements of the stronger, C-dependent promoter are indicated by heavy rectangles, while thinner rectangles indicate the weak C-independent promoter. Transcript starts are indicated by bent arrows. (C) C-box sequence Logos. The Logos represent the subset of C-box regions associated with the subset of C proteins having HRTY in the recognition helix [21 cases, (28)]. The Logo (55) was generated by the server at http://weblogo.berkeley.edu. The C-box intra-operator spacers are boxed, and the central TGTA inter-operator spacer is underlined.