PPR-SMR protein SOT1 has RNA endonuclease activity

Abstract

Significance Our results demonstrate that SUPPRESSOR OF THYLAKOID FORMATION 1 (SOT1), an Arabidopsis pentatricopeptide repeat (PPR) protein with a small MutS-related (SMR) domain, has endonuclease activity. The SMR moiety of SOT1 performs the endonucleolytic maturation of 23S and 4.5S rRNA through the PPR domain specifically recognizing a 13-nucleotide RNA sequence in the 5′ end of the chloroplast 23S–4.5S rRNA precursor. Our results also show that SOT1 can be engineered to recognize and cleave a predicted RNA substrate. Our findings suggest that SOT1 could be used as a tool for RNA manipulation in the future.