Regulation of Streptococcus mutans PTS^Bio by the transcriptional repressor NigR

Abstract

SUMMARY Streptococcus mutans is implicated in human dental caries, and the carbohydrate metabolism of this organism plays an important role in the formation of this disease. Carbohydrate transport and metabolism are essential for the survival of S. mutans in the oral cavity. It is known that a unique phosphoenolpyruvate-sugar phosphotransferase system PTSBio of S. mutans UA159 is expressed in sucrose-grown biofilms (Mol Oral Microbiol 28: 2013; 114). In this study we analyzed the transcriptional regulation of the operon (OBio) encoding the PTSBio and showed that it was repressed by NigR, a LacI-like transcriptional regulator. Using electromobility shift assay, we described two operators to which NigR bound with different affinities. We also identified the transcriptional start site and showed that one of the operators overlaps with the promoter and presumably represses initiation of transcription. Mutational analyses revealed the key nucleotides in the operators required for high-affinity binding of NigR. PTSBio is expressed in S. mutans biofilms so understanding its regulation may provide improved strategies for caries treatment and prevention.

The Route of Sucrose Utilization by Streptococcus mutans Affects Intracellular Polysaccharide Metabolism

“…Each assay was performed with biological and technical triplicates. For each gene, the mRNA levels were normalized against that of gyrA transcript ( Vujanac et al, 2015 ; Zeng and Burne, 2016 ) using the ∆∆Cq method ( Schmittgen and Livak, 2008 ; Rocha et al, 2015 ) and presented as relative abundance in comparison to the results of the control group (Glu+Fru) at time 0h.…”

Spontaneous Mutants of Streptococcus sanguinis with Defects in the Glucose-PTS Show Enhanced Post-Exponential Phase Fitness

“…To synthesize cDNA, 0.5 µg of each RNA sample was used in a 10-µL reverse transcription reaction set up using the iScript Select cDNA synthesis kit (Bio-Rad), together with gene-specific reverse primers (Table S2) used at 200 nM each. Primer for the housekeeping gene gyrA was used as an internal control in all cases (67). After a 10-fold dilution with water, the cDNA was used as a template in a quantitative PCR (qPCR) reaction prepared using a SsoAdvanced Universal SYBR Green Supermix and cycled on a CFX96 Real-Time PCR Detection System (Bio-Rad), following the supplier's instructions.…”

Transcriptional Profiling Reveals the Importance of RcrR in the Regulation of Multiple Sugar Transportation and Biofilm Formation in Streptococcus mutans

“…Sugar transport and metabolism are regulated by different mechanisms ( 15 ). Organisms can express and coordinate the regulation of multiple sugar uptake systems in response to complex environments.…”

“…Organisms can express and coordinate the regulation of multiple sugar uptake systems in response to complex environments. Previous studies have postulated that PTS systems are widely regulated by various factors, such as FruR ( 9 ), StsR ( 12 ), TreR ( 13 ), CelR ( 14 ), and NigR ( 15 ). For example, deletion of stsR changes the expression levels of PTS and ABC transporter genes, including mannitol- and trehalose-specific PTS systems ( 12 ).…”

“…However, there are also negative regulators. For instance, FruR and NigR negatively regulate the transcription of the fruRKI operon and the PTS Bio operon, respectively ( 9 , 15 ).…”