Overexpression of APOBEC-1 results in mooring sequence-dependent promiscuous RNA editing.
Apolipoprotein B (apoB) RNA editing involves site-specific deamination of a cytidine to a uridine. A mooring sequence, a spacer region, and a regulator region are components of the apoB RNA editing motif of which only the mooring sequence is both necessary and sufficient for editosome assembly and editing. The catalytic component of the editosome is APOBEC-1. In rat hepatoma, stable cell lines, overexpression of APOBEC-1 resulted in 3 6-fold stimulation of the editing efficiency on either rat endogenous apoB RNA or transiently expressed human apoB RNA. In these cell lines, cytidines in addition to the one at the wild type site were edited. The occurrence and efficiency of this "promiscuous" editing increased with increasing expression of APOBEC-1. Promiscuous editing was restricted to cytidines 5' of the mooring sequence and only occurred on RNAs that had been edited at the wild type site. Moreover, RNAs with mutant editing motifs supported high efficiency but low fidelity editing in the presence of high levels of APOBEC-1. This study demonstrates that overexpression of APOBEC-1 can increase the efficiency of site-specific editing but can also result in promiscuous editing.
Sowden
M
M
Department of Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA.
Hamm
J K
JK
Smith
H C
HC
D000071479:APOBEC-1 Deaminase; D000818:Animals; D001055:Apolipoproteins B / Q000096:biosynthesis*; D001483:Base Sequence; D002460:Cell Line; D003564:Cytidine Deaminase / Q000096:biosynthesis / Q000378:metabolism*; D017931:DNA Primers; D015870:Gene Expression; D006801:Humans; D008114:Liver Neoplasms, Experimental; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D016133:Polymerase Chain Reaction; D012313:RNA / Q000378:metabolism*; D017393:RNA Editing; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D001055:Apolipoproteins B; D017931:DNA Primers; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D012313:RNA; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D000071479:APOBEC-1 Deaminase; C000605089:APOBEC1 protein, human; C000605091:Apobec1 protein, rat; D003564:Cytidine Deaminase