C to U RNA editing mediated by APOBEC1 requires RNA-binding protein RBM47

Cytidine (C) to Uridine (U) RNA editing is a post-transcriptional modification that is accomplished by the deaminase APOBEC1 and its partnership with the RNA-binding protein A1CF. We identify and characterise here a novel RNA-binding protein, RBM47, that interacts with APOBEC1 and A1CF and is expressed in tissues where C to U RNA editing occurs. RBM47 can substitute for A1CF and is necessary and sufficient for APOBEC1-mediated editing in vitro. Editing is further impaired in Rbm47-deficient mutant mice. These findings suggest that RBM47 and APOBEC1 constitute the basic machinery for C to U RNA editing. Synopsis The RNA-binding protein RBM47 is required for normal Cytidine to Uridine RNA editing in mice and is sufficient for the C to U editing activity of APOBEC1, indicating that the composition of the editosome holoenzyme needs to be revised. RBM47 is found in the epithelial cells of the intestine and interacts with APOBEC1 and A1CF. RBM47 can replace A1CF and is sufficient with APOBEC1 for C to U RNA editing. C to U editing of Apob and other RNA is impaired in Rbm47-deficient mice. The RNA-binding protein RBM47 is required for normal Cytidine to Uridine RNA editing in mice and is sufficient for the C to U editing activity of APOBEC1, indicating that the composition of the editosome holoenzyme needs to be revised.