Group 2 Sigma Factor SigB of Corynebacterium glutamicum Positively Regulates Glucose Metabolism under Conditions of Oxygen Deprivation

Abstract

The sigB gene of Corynebacterium glutamicum encodes a group 2 sigma factor of RNA polymerase. Under conditions of oxygen deprivation, the sigB gene is upregulated and cells exhibit high productivity of organic acids as a result of an elevated glucose consumption rate. Using DNA microarray and quantitative reverse transcription-PCR (RT-PCR) analyses, we found that sigB disruption led to reduced transcript levels of genes involved in the metabolism of glucose into organic acids. This in turn resulted in retardation of glucose consumption by cells under conditions of oxygen deprivation. These results indicate that SigB is involved in positive regulation of glucose metabolism genes and enhances glucose consumption under conditions of oxygen deprivation. Moreover, sigB disruption reduced the transcript levels of genes involved in various cellular functions, including the glucose metabolism genes not only in the growth-arrested cells under conditions of oxygen deprivation but also in the cells during aerobic exponential growth, suggesting that SigB functions as another vegetative sigma factor.

Lactate production as representative of the fermentation potential of Corynebacterium glutamicum 2262 in a one-step process

“…13) Upregulation of these genes is controlled by SigB, a group-2 sigma factor, which has been found to be expressed during the transition from exponential phase to stationary phase, under various stresses, and under oxygen deprivation in C. glutamicum. 14) As a consequence, a metabolic shift is driven from the glycolytic pathway toward the reductive arm of the TCA cycle, enabling an increase in organic acid production. 15) From a biotechnological point of view, these modifications of the physiological state of cells during the transition from aerobic to anaerobic conditions probably constitute critical points.…”

Regulation of Quinone Oxidoreductase by the Redox-sensing Transcriptional Regulator QorR in Corynebacterium glutamicum

“…This is the first report on a DUF24 family protein other than those of B. subtilis to our knowledge. 33°C in A medium with 4% (w/v) glucose as described previously (18). Disruptants of the qorR (cgR_1435) and qor2 (cgR_1436) genes were constructed by the transposon-mediated mutagenesis method as described previously (19).…”

“…Real-time qRT-PCR-A one-step real-time quantitative reverse transcription-PCR (qRT-PCR) 2 was performed with the Power SYBR Green PCR Master Mix (Applied BioSystems) and a pair of gene-specific primers (supplemental Table S1) by using the 7500 Fast Real-time PCR system (Applied BioSystems) as described previously (18). Relative ratios were normalized with the value for 16 S rRNA.…”

“…RNA Isolation and DNA Microarray Analysis-Total RNA was extracted from C. glutamicum cells by using the RNeasy Mini kit (Qiagen) and was treated with DNase I (Takara Bio, Inc.) as described previously (18). Global gene expression analysis was performed with the C. glutamicum R DNA microarray as described previously (18).…”

“…Global gene expression analysis was performed with the C. glutamicum R DNA microarray as described previously (18). Microarray analyses were carried out using two sets of RNA samples isolated from independently grown cultures with different combinations of Cy dyes (a dye swap strategy).…”