Effects of Global and Specific DNA-Binding Proteins on Transcriptional Regulation of the <i>E. coli bgl</i> Operon
Using reporter gene (<i>lacZ</i>) transcriptional fusions<i>,</i> we examined the transcriptional dependencies of the <i>bgl</i> promoter (P<i>bgl</i>) and the entire operon regulatory region (P<i>bgl</i>-<i>bglG</i>) on eight t...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-09-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/23/18/10343 |
| Summary: | Using reporter gene (<i>lacZ</i>) transcriptional fusions<i>,</i> we examined the transcriptional dependencies of the <i>bgl</i> promoter (P<i>bgl</i>) and the entire operon regulatory region (P<i>bgl</i>-<i>bglG</i>) on eight transcription factors as well as the inducer, salicin, and an IS5 insertion upstream of P<i>bgl</i>. Crp-cAMP is the primary activator of both P<i>bgl</i> and the <i>bgl</i> operon, while H-NS is a strong dominant operon repressor but only a weak repressor of P<i>bgl</i>. H-NS may exert its repressive effect by looping the DNA at two binding sites. StpA is a relatively weak repressor in the absence of H-NS, while Fis also has a weak repressive effect. Salicin has no effect on P<i>bgl</i> activity but causes a 30-fold induction of <i>bgl</i> operon expression. Induction depends on the activity of the BglF transporter/kinase. IS5 insertion has only a moderate effect on P<i>bgl</i> but causes a much greater activation of the <i>bgl</i> operon expression by preventing the full repressive effects of H-NS and StpA. While several other transcription factors (BglJ, RcsB, and LeuO) have been reported to influence <i>bgl</i> operon transcription when overexpressed, they had little or no effect when present at wild type levels. These results indicate the important transcriptional regulatory mechanisms operative on the <i>bgl</i> operon in <i>E. coli</i>. |
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| ISSN: | 1661-6596 1422-0067 |