Transcription factors of the GntR type possess two domains: a DNA binding domain in the N-terminal part, and a putative ligand-binding domain in the C-terminal section. Upon ligand binding, the protein activity is modified, leading to a change in the regulation of gene expression. Therefore, GntR-type transcriptional regulators are prime candidates to synchronize metabolism and transcription, especially in Cyanobacteria with their versatile pathways for photosynthesis-driven carbon and nitrogen assimilation. With their new paper “The GntR family transcriptional regulator PMM1637 regulates the highly conserved cyanobacterial sRNA Yfr2 in marine picocyanobacteria” the cyanolabbers Joke, Mascha and Claudia provide for the first time insight into the activity of such a transcription factor from the marine cyanobacterium Prochlorococcus MED4.