3′ Untranslated Region-Dependent Degradation of the aceA mRNA, Encoding the Glyoxylate Cycle Enzyme Isocitrate Lyase, by RNase E/G in Corynebacterium glutamicum

We previously reported that theCorynebacterium glutamicum RNase E/G encoded by therneG gene (NCgl2281) is required for the 5′ maturation of 5S rRNA. In the search for the intracellular target RNAs of RNase E/G other than the 5S rRNA precursor, we detected that the amount of isocitrate lyase, an enzyme of the glyoxylate cycle, increased inrneG knockout mutant cells grown on sodium acetate as the sole carbon source. Rifampin chase experiments showed that the half-life of theaceA mRNA was about 4 times longer in therneG knockout mutant than in the wild type. Quantitative real-time PCR analysis also confirmed that the level ofaceA mRNA was approximately 3-fold higher in therneG knockout mutant strain than in the wild type. Such differences were not observed in other mRNAs encoding enzymes involved in acetate metabolism. Analysis by 3′ rapid amplification of cDNA ends suggested that RNase E/G cleaves theaceA mRNA at a single-stranded AU-rich region in the 3′ untranslated region (3′-UTR). ThelacZ fusion assay showed that the 3′-UTR renderedlacZ mRNA RNase E/G dependent. These findings indicate that RNase E/G is a novel regulator of the glyoxylate cycle inC. glutamicum .