Short ROSE-like RNA thermometers control IbpA synthesis in Pseudomonas species

PLoS One. 2013 May 31;8(5):e65168. doi: 10.1371/journal.pone.0065168. Print 2013.

Abstract

The bacterial small heat shock protein IbpA protects client proteins from aggregation. Due to redundancy in the cellular chaperone network, deletion of the ibpA gene often leads to only a mild or no phenotypic defect. In this study, we show that a Pseudomonas putida ibpA deletion mutant has a severe growth defect under heat stress conditions and reduced survival during recovery revealing a critical role of IbpA in heat tolerance. Transcription of the ibpA gene depends on the alternative heat shock sigma factor σ(32). Production of IbpA protein only at heat shock temperatures suggested additional translational control. We conducted a comprehensive structural and functional analysis of the 5' untranslated regions of the ibpA genes from P. putida and Pseudomonas aeruginosa. Both contain a ROSE-type RNA thermometer that is substantially shorter and simpler than previously reported ROSE elements. Comprised of two hairpin structures only, they inhibit translation at low temperature and permit translation initiation after a temperature upshift. Both elements regulate reporter gene expression in Escherichia coli and ribosome binding in vitro in a temperature-dependent manner. Structure probing revealed local melting of the second hairpin whereas the first hairpin remained unaffected. High sequence and structure conservation of pseudomonal ibpA untranslated regions and their ability to confer thermoregulation in vivo suggest that short ROSE-like thermometers are commonly used to control IbpA synthesis in Pseudomonas species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions
  • Base Sequence
  • Conserved Sequence
  • Gene Expression
  • Gene Expression Regulation, Bacterial
  • Genes, Reporter
  • Heat-Shock Proteins / biosynthesis*
  • Molecular Sequence Data
  • Mutation
  • Nucleic Acid Conformation
  • Nucleic Acid Denaturation
  • Phenotype
  • Protein Binding
  • Pseudomonas / genetics*
  • Pseudomonas / metabolism*
  • RNA, Bacterial / genetics*
  • RNA, Bacterial / metabolism
  • Ribosome Subunits, Small, Bacterial / metabolism
  • Sequence Alignment
  • Temperature
  • Transcription Initiation Site
  • Transcription, Genetic

Substances

  • 5' Untranslated Regions
  • Heat-Shock Proteins
  • RNA, Bacterial

Grants and funding

This work was financially supported by a grant from the German Research Foundation (DFG priority program SPP 1258: Sensory and regulatory RNAs in Prokaryotes) to FN. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.