6mer Seed Toxicity in Viral microRNAs

MicroRNAs (miRNAs) are short double-stranded noncoding RNAs (19-23 nucleotides) that regulate gene expression by suppressing mRNAs through RNA interference. Targeting is determined by the seed sequence (position 2-7/8) of the mature miRNA. A minimal G-rich seed of just six nucleotides is highly toxic to cells by targeting genes essential for cell survival. A screen of 215 miRNAs encoded by 17 human pathogenic viruses (v-miRNAs) now suggests that...