The general transcription termination factor CPSF1 is ubiquitously distributed among Archaea (aCPSF1). It was recently characterised as a ribonuclease essential for transcription termination to ensure programmed transcriptome and an optimal growth and physiology. It associates with archaeal RNAP and cleaves the transcript at the 3'-end, downstream the uridine-rich sequences recognised by its N-terminal KH-domain, a characteristic RNA binding domain [, ].