BioProject

Endoribonucleases govern the maturation and degradation of RNA and are indispensable in the post-transcriptional regulation of gene expression. More...

Endoribonucleases govern the maturation and degradation of RNA and are indispensable in the post-transcriptional regulation of gene expression. A key endoribonuclease in many bacteria is RNase E. To ensure an appropriate supply of RNase E, some bacteria such as E. coli have evolved a tightly functioning feedback regulation of RNase E, which is mediated in cis by the rne 5′-untranslated region (5′UTR); however, the mechanisms involved in the control of RNase E in other bacteria have largely remained unknown. Cyanobacteria rely on solar light as energy source for their photosynthetic lifestyle, despite the inherent ultraviolet (UV) irradiation. Here, we revealed the global gene expression response in the cyanobacterium Synechocystis sp. PCC 6803 after exposure to UV light and discovered a unique response of RNase E: a rapidly increasing enzymatic activity although stability of the protein was lowered . In parallel, we observed a substantial stabilization of the full-length mRNA specifically after UV-C treatment, while the 5′UTR accumulated under all conditions. Mapping of RNA 3′ends and in vitro cleavage assays revealed that RNase E cleaves within a stretch of six consecutive uridine residues within the rne 5′UTR, indicating the autoregulation of RNase E via its own 5′UTR. These observations imply that RNase E in cyanobacteria evolved as a substantial contributor in re-shaping the transcriptome during the UV stress response, that its required activity level is maintained despite enhanced turnover of the protein, and that the underlying mechanism involves a feedback mechanism acting on a uridine-rich element within the rne 5′UTR. Overall design: We performed microarray analysis of total RNA from UV-stressed cultures and cultures that were not dtressed (mock). Sampling time points were t1 = 1h +/- UV, t2 = 2h +/- UV. Samples were taken in biological duplicates. Less...