Abstract
Rhizobium leguminosarum bv. trifolii is a soil bacterium capable of establishing a symbiotic relationship with clover (Trifolium spp.). Previously, the rosR gene, encoding a global regulatory protein involved in motility, synthesis of cell-surface components, and other cellular processes was identified and characterized in this bacterium. This gene possesses a long upstream region that contains several regulatory motifs, including inverted repeats (IRs) of different lengths. So far, the role of these motifs in the regulation of rosR transcription has not been elucidated in detail. In this study, we performed a functional analysis of these motifs using a set of transcriptional rosR-lacZ fusions that contain mutations in these regions. The levels of rosR transcription for different mutant variants were evaluated in R. leguminosarum using both quantitative real-time PCR and β-galactosidase activity assays. Moreover, the stability of wild type rosR transcripts and those with mutations in the regulatory motifs was determined using an RNA decay assay and plasmids with mutations in different IRs located in the 5′-untranslated region of the gene. The results show that transcription of rosR undergoes complex regulation, in which several regulatory elements located in the upstream region and some regulatory proteins are engaged. These include an upstream regulatory element, an extension of the -10 element containing three nucleotides TGn (TGn-extended -10 element), several IRs, and PraR repressor related to quorum sensing.
Highlights
Rhizobium leguminosarum bv. trifolii is a soil bacterium that establishes nitrogen-fixing symbiosis with clover (Trifolium spp.)
It was established that a regulatory protein encoded by the rosR gene is essential for the adaptation of R. leguminosarum to stress conditions, affecting the expression of many genes related to the synthesis of surface polysaccharides and cell-surface components, secretion of extracellular proteins, motility, and other cellular processes [3,4,5]
In R. leguminosarum, the transcription factors (TFs) encoded by rosR is a global regulator that plays an essential role in this regulatory network
Summary
Rhizobium leguminosarum bv. trifolii is a soil bacterium that establishes nitrogen-fixing symbiosis with clover (Trifolium spp.). It was established that a regulatory protein encoded by the rosR gene is essential for the adaptation of R. leguminosarum to stress conditions, affecting the expression of many genes related to the synthesis of surface polysaccharides and cell-surface components, secretion of extracellular proteins, motility, and other cellular processes [3,4,5]. This gene encodes a 15.7 kDa global transcriptional regulator, which contains a Cys2 -His2 -type zinc finger motif responsible for binding to RosR-box motifs located in the promoter regions of the regulated genes [4,6]. In contrast to eukaryotic transcription factors (TFs), which typically contain tandem arrays of such Cys2 -His zinc fingers, bacterial proteins, including the rhizobial RosR/MucR family, possess only one Cys2 -His2 -type zinc finger motif located in their
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
