FIG. 5.

On the left-hand side is shown a representation of the las cluster regulatory region. The features indicated are the experimentally determined transcription initiation points (bent arrows), the deduced promoter elements (underlined), direct repeats (marked DR1 to DR3 [with brackets]), and the proposed ribosome-binding sites (boldface letters). The roman numerals refer to the 5" ends of the two RNA species representing lasA (38). To the right is shown the result of the primer extension experiment performed to determine the 5" end of lasX (and/or lasXY) mRNA. The arrow indicates the extension product of the primer 1295TC (Table 2), which was run alongside a sequence reaction with 1295TC and plas7.5-1 as a template.