Multiple factors interact in editing of PPR-E+-targeted sites in maize mitochondria and plastids

RNA cytidine-to-uridine editing is essential for plant organellar gene expression.Pentatricopeptide repeat(PPR)-E+ proteins have been proposed to bind to target sites and recruit the cytidine deaminase AtDYW2,facilitated by AtNUWA.Here we analyze the function of ZmNUWA,ZmDYW2A,and ZmDYW2B and their re-lationships with other editing factors in maize.The zmdyw2a and zmdyw2b single mutants are normal,but the zmdyw2a::zmdyw2b and zmnuwa mutants are severely arrested in seed development.ZmNUWA,ZmDYW2A,and ZmDYW2B are dual localized in mitochondria and plastids.Loss of ZmNUWA decreases the editing at 99 mitochondrial sites and 8 plastid sites.Surprisingly,loss of ZmDYW2A:ZmDYW2B affects almost the same set of sites targeted by PPR-E+ proteins.ZmNUWA interacts with ZmDYW2A and ZmDYW2B,suggesting that ZmNUWA recruits ZmDYW2A/2B in the editing of PPR-E+-targeted sites in maize.Further protein interaction analyses show that ZmNUWA and ZmDYW2A/2B interact with ZmMORF1,ZmMORF8,ZmMORF2,and ZmMORF9 and that ZmOZ1 interacts with ZmORRM1,ZmDYW2A,ZmDYW2B,ZmMORF8,and ZmMORF9.These results suggest that the maize mitochondrial PPR-E+editosome contains PPR-E+,ZmDYW2A/2B,ZmNUWA,and ZmMORF1/8,whereas the plastid PPR-E+editosome is composed of PPR-E+,ZmDYW2A/2B,ZmNUWA,ZmMORF2/8/9,ZmORRM1,and ZmOZ1.