Résumé : Bacterial regulatory small RNAs (sRNAs) act as crucial regulators in central carbon metabolism by modulating translation initiation and/or degradation of target mRNAs in metabolic pathways. This work demonstrates that a noncoding sRNA, SdhX, is produced by RNase E-dependent processing from the 3 ́ untranslated region (3 ́ UTR) of an operon encoding three enzymes of the tricarboxylic acid (TCA) cycle. In Escherichia coli, SdhX negatively regulates ackA (encoding an enzyme critical for degradation of the signaling molecule acetyl phosphate) without affecting the downstream pta gene that encodes the enzyme critical for acetyl phosphate synthesis. SdhX abundance is tightly coupled to the transcription signals of the TCA cycle genes but escapes all known post-transcriptional regulation. Therefore, SdhX expression directly correlates with transcriptional input to the TCA cycle, providing an effective mechanism for the cell to link the TCA cycle with acetate metabolism pathways.