TY - JOUR TI - An evolutionarily conserved RNase-based mechanism for repression of transcriptional positive autoregulation. AU - Wurtmann, Elisabeth J. AU - Ratushny, Alexander V. AU - Pan, Min AU - Beer, Karlyn D. AU - Aitchison, John D. AU - Baliga, Nitin S. T2 - Molecular microbiology AB - It is known that environmental context influences the degree of regulation at the transcriptional and post-transcriptional levels. However, the principles governing the differential usage and interplay of regulation at these two levels are not clear. Here, we show that the integration of transcriptional and post-transcriptional regulatory mechanisms in a characteristic network motif drives efficient environment-dependent state transitions. Through phenotypic screening, systems analysis, and rigorous experimental validation, we discovered an RNase (VNG2099C) in Halobacterium salinarum that is transcriptionally co-regulated with genes of the aerobic physiologic state but acts on transcripts of the anaerobic state. Through modelling and experimentation we show that this arrangement generates an efficient state-transition switch, within which RNase-repression of a transcriptional positive autoregulation (RPAR) loop is critical for shutting down ATP-consuming active potassium uptake to conserve energy required for salinity adaptation under aerobic, high potassium, or dark conditions. Subsequently, we discovered that many Escherichia coli operons with energy-associated functions are also putatively controlled by RPAR indicating that this network motif may have evolved independently in phylogenetically distant organisms. Thus, our data suggest that interplay of transcriptional and post-transcriptional regulation in the RPAR motif is a generalized principle for efficient environment-dependent state transitions across prokaryotes. DA - 2014/04//undefined PY - 2014 DO - 10.1111/mmi.12564 VL - 92 IS - 2 SP - 369 EP - 382 J2 - Mol Microbiol LA - eng SN - 1365-2958 0950-382X KW - *Gene Expression Regulation KW - *Homeostasis KW - *RNA Interference KW - *Transcription, Genetic KW - Aerobiosis KW - Anaerobiosis KW - Energy Metabolism KW - Escherichia coli/genetics/metabolism KW - Halobacterium salinarum/*genetics/metabolism KW - Osmotic Pressure KW - Phenotype KW - Potassium/metabolism KW - Ribonucleases/*metabolism KW - Stress, Physiological ER -