Plays a major role in single RNA editing events in chloroplasts. Acts as a site-recognition transacting factor involved in the edition of the site 1 of ndhD (ndhD-1 site corresponding to cytidine-2), which is a plastid-encoded subunit of the NADH-plastoquinone oxidoreductase. The interaction with CRR4 is required for its function in editing the ndhD-1 site. Binds 2 zinc ions per subunit. Interacts with CRR4. No visible phenotype under normal growth conditions, but the mutant plants lack editing of the ndhD-1 site. Unlike other RNA editing factors, DYW1 does not contain identifiable PPR repeats but does contain E(+) and DYW motifs. Therefore its association with CCR4, which lacks E(+) and DYW motifs, but does contain PPR repeats, is required for its function in RNA editing. Belongs to the PPR family. PCMP-H subfamily. The predicted gene has been split into 2 genes: At1g47578 and At1g47580.