Members of the ClpS family of N-recognins identify targets bearing specific N-terminal amino acids for destruction via the bacterial N-end pathway rule. Here, Colombo et al. (on pp. 624-636) identified ClpS1 in Arabidopsis thaliana chloroplasts and analysed its interaction with canonical N-terminal residues of target proteins. They found that ClpS1 has a similar specificity to its bacterial counterparts, albeit at a lower affinity. In addition, they found that an arginine residue, instead of a methionine residue in bacteria, acts as the gatekeeper for fine-tuning the specificity of the N-recognin in plants; while an Arg to Met mutation in ClpS1 significantly increases its ability to recognize canonical N-degrons.