Termination factor Rho: From the control of pervasive transcription to cell fate determination in Bacillus subtilis

PLoS Genet. 2017 Jul 19;13(7):e1006909. doi: 10.1371/journal.pgen.1006909. eCollection 2017 Jul.

Abstract

In eukaryotes, RNA species originating from pervasive transcription are regulators of various cellular processes, from the expression of individual genes to the control of cellular development and oncogenesis. In prokaryotes, the function of pervasive transcription and its output on cell physiology is still unknown. Most bacteria possess termination factor Rho, which represses pervasive, mostly antisense, transcription. Here, we investigate the biological significance of Rho-controlled transcription in the Gram-positive model bacterium Bacillus subtilis. Rho inactivation strongly affected gene expression in B. subtilis, as assessed by transcriptome and proteome analysis of a rho-null mutant during exponential growth in rich medium. Subsequent physiological analyses demonstrated that a considerable part of Rho-controlled transcription is connected to balanced regulation of three mutually exclusive differentiation programs: cell motility, biofilm formation, and sporulation. In the absence of Rho, several up-regulated sense and antisense transcripts affect key structural and regulatory elements of these differentiation programs, thereby suppressing motility and biofilm formation and stimulating sporulation. We dissected how Rho is involved in the activity of the cell fate decision-making network, centered on the master regulator Spo0A. We also revealed a novel regulatory mechanism of Spo0A activation through Rho-dependent intragenic transcription termination of the protein kinase kinB gene. Altogether, our findings indicate that distinct Rho-controlled transcripts are functional and constitute a previously unknown built-in module for the control of cell differentiation in B. subtilis. In a broader context, our results highlight the recruitment of the termination factor Rho, for which the conserved biological role is probably to repress pervasive transcription, in highly integrated, bacterium-specific, regulatory networks.

MeSH terms

  • Bacillus subtilis / genetics
  • Bacterial Proteins / genetics*
  • Biofilms / growth & development
  • Cell Movement / genetics
  • Gene Expression Regulation, Bacterial
  • Gene Regulatory Networks / genetics
  • Promoter Regions, Genetic
  • Rho Factor / genetics*
  • Spores, Bacterial / genetics
  • Transcription Factors / genetics*
  • Transcription Termination, Genetic*
  • Transcription, Genetic*
  • Transcriptome / genetics

Substances

  • Bacterial Proteins
  • Rho Factor
  • Spo0A protein, Bacillus subtilis
  • Transcription Factors

Grants and funding

AGM was supported by the co-tutelle PhD scholarship funded by French Government and Program “Partenariats Hubert Curien 2015-2016” (Project 33445ZA) funded by French Ministry of Foreign Affairs and International Development. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.