DnaA and LexA Proteins Regulate Transcription of the uvrB Gene in Escherichia coli: The Role of DnaA in the Control of the SOS Regulon

作者：Wurihan; Gezi; Brambilla, Elisa; Wang, Shuwen; Sun, Hongwei; Fan, Lifei; Shi, Yixin; Sclavi, Bianca^*; Morigen^*

来源：Frontiers in Microbiology, 2018, 9: 1212.

DOI：10.3389/fmicb.2018.01212

• DnaA
• LexA
• uvrB gene expression
• SOS regulon
• regulation

The uvrB gene belongs to the SOS network, encoding a key component of the nucleotide excision repair. The uvrB promoter region contains three identified promoters with four LexA binding sites, one consensus and six potential DnaA binding sites. A more than threefold increase in transcription of the chromosomal uvrB gene is observed in both the Delta lexA Delta sulA cells and dnaA(A345S) cells, and a fivefold increase in the Delta lexA Delta sulA dnaA(A345S) cells relative to the wild-type cells. The full activity of the uvrB promoter region requires both the uvrBp1-2 and uvrBp3 promoters and is repressed by both the DnaA and LexA proteins. LexA binds tightly to LexA-box1 at the uvrBp-12 promoter irrespective of the presence of DnaA and this binding is important for the control of the uvrBp1-2 promoter. DnaA and LexA, however, compete for binding to and regulation of the uvrBp3 promoter in which the DnaA-box6 overlaps with LexAbox4. The transcription control of uvrBp3 largely depends on DnaA-box6. Transcription of other SOS regulon genes, such as recN and dinJ, is also repressed by both DnaA and LexA. Interestingly, the absence of LexA in the presence of the DnaA(A345S) mutant leads to production of elongated cells with incomplete replication, aberrant nucleoids and slow growth. We propose that DnaA is a modulator for maintenance of genome integrity during the SOS response by limiting the expression of the SOS regulon.

• 出版日期2018-6-18
• 单位内蒙古大学