The transcription of thegluQ-rsgene is controlled by a termination stem loop.A) Schematic representation of the operon, the arrows indicate the position of each promoter identified by our bioinformatics analysis and experimentally determined by Kang and Craig, 1990 . The putative ρ-independent terminator is represented by the stem loop symbol upstream of gluQ-rs gene. The horizontal bar represents the DNA region amplified and cloned into pQF50 (Table 1). The recombinant plasmids are described in Table 1. pVCDT does not have the dksA promoter but has the terminator. pVCPDT has the promoter region of dksA and the terminator upstream of gluQ-rs; therefore, it represents the genomic organization of the operon. pVCPD also has the promoter of dksA but lacks the terminator region. The size of each fragment is indicated. B) β-galactosidase activity of each protein extract obtained from the corresponding clone. The data represent the average of three experiments in triplicates and the Student t test was used to compare the means between each clone with the empty vector. *** p values <0.05 were considered statistically significant.
Caballero et al. BMC Microbiology 2012 12:226 doi:10.1186/1471-2180-12-226