title: Describing the structural robustness landscape of bacterial small RNAs.
abstract: BACKGROUND
  The potential role of RNA molecules as gene expression regulators has led to a new perspective on the intracellular control and genome organization. Because secondary structures are crucial for their regulatory role, we sought to investigate their robustness to mutations and environmental changes.
  
  
  RESULTS
  Here, we dissected the structural robustness landscape of the small non-coding RNAs (sncRNAs) encoded in the genome of the bacterium Escherichia coli. We found that bacterial sncRNAs are not significantly robust to both mutational and environmental perturbations when compared against artificial, unbiased sequences. However, we found that, on average, bacterial sncRNAs tend to be significantly plastic, and that mutational and environmental robustness strongly correlate. We further found that, on average, epistasis in bacterial sncRNAs is significantly antagonistic, and positively correlates with plasticity. Moreover, the evolution of robustness is likely dependent upon the environmental stability of the cell, with more fluctuating environments leading to the emergence and fixation of more robust molecules. Mutational robustness also appears to be correlated with structural functionality and complexity.
  
  
  CONCLUSIONS
  Our study provides a deep characterization of the structural robustness landscape of bacterial sncRNAs, suggesting that evolvability could be evolved as a consequence of selection for more plastic molecules. It also supports that environmental fluctuations could promote mutational robustness. As a result, plasticity emerges to link robustness, functionality and evolvability.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas, Universidad Politécnica de Valencia, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain. guirodta@ibmcp.upv.es
authors.forename: Guillermo
authors.initials: G
authors.lastname: Rodrigo
authors.forename: Mario A
authors.initials: MA
authors.lastname: Fares
mesh_terms: D004843:Epistasis, Genetic / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D019143:Evolution, Molecular; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics*; D009690:Nucleic Acid Conformation; D059370:RNA Folding / Q000502:physiology*; D058727:RNA, Small Untranslated / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D058727:RNA, Small Untranslated