Dynamic Expression of the Translational Machinery during Bacillus subtilis Life Cycle at a Single Cell Level

Abstract

The ability of bacteria to responsively regulate the expression of translation components is crucial for rapid adaptation to fluctuating environments. Utilizing Bacillus subtilis (B. subtilis) as a model organism, we followed the dynamics of the translational machinery at a single cell resolution during growth and differentiation. By comprehensive monitoring the activity of the major rrn promoters and ribosomal protein production, we revealed diverse dynamics between cells grown in rich and poor medium, with the most prominent dissimilarities exhibited during deep stationary phase. Further, the variability pattern of translational activity varied among the cells, being affected by nutrient availability. We have monitored for the first time translational dynamics during the developmental process of sporulation within the two distinct cellular compartments of forespore and mother-cell. Our study uncovers a transient forespore specific increase in expression of translational components. Finally, the contribution of each rrn promoter throughout the bacterium life cycle was found to be relatively constant, implying that differential expression is not the main purpose for the existence of multiple rrn genes. Instead, we propose that coordination of the rrn operons serves as a strategy to rapidly fine tune translational activities in a synchronized fashion to achieve an optimal translation level for a given condition.

Following the Fate of Bacterial Cells Experiencing Sudden Chromosome Loss

“…To address this issue, we conducted a f luorescence r ecovery a fter p hotobleaching (FRAP) assay, monitoring DLCs expressing RplA-GFP. Following photobleached DLCs by time lapse microscopy revealed recovery of the signal, though with slow kinetics ( 26 ), as evidenced by the increase in fluorescence 1 to 2 h post-bleaching ( Fig. 3C ; see Fig.…”

“…S4A in the supplemental material). We next examined in detail the stability of specific proteins with diverse cellular functions: RplA, a ribosomal subunit ( 25 , 26 ), Spo0J, a DNA binding protein involved in chromosome segregation ( 27 – 29 ), ManP, a membrane transporter of mannose ( 30 ), and FtsZ, the major cell division protein ( 31 , 32 ). To this end, DLCs harboring GFP fusions to each of the representative proteins were subjected to Western blot analysis.…”

Spx, the central regulator of the heat and oxidative stress response in B. subtilis, can repress transcription of translation‐related genes

“…In order to assess the effect of Spx on rRNA expression, we combined an array of strains carrying transcriptional rrn‐gfp fusions in the amyE site (Rosenberg et al , ) with an IPTG‐inducible copy of spx DD in the lacA site (Fig. A).…”

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“…The Bacillus subtilis is aerobic, non-pathogenic bacteria found in soil, water, air and healthy to humus plant and animal debris 31,32 . A number of Bacillus species are useful for a number of industrial applications due to its capability for production of large number of enzymes 33,34 .…”