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. 2015 Feb 16;5(1):538–553. doi: 10.3390/life5010538

Figure 3.

Figure 3

Putative mechanisms of bacterial Ago-mediated silencing pathways. (I) Guide sequences of Thermus thermophilus Ago (TtAgo) and Rhodobacter sphaeroides Ago (RsAgo) are derived from plasmid DNA or RNA transcripts, respectively. (II) TtAgo is loaded with a 13–25-nt guide DNA and RsAgo with a 15–19-nt guide RNA. (III) The target substrates are (a) ssRNA, (b) negatively-supercoiled plasmid DNA and (c) ssDNAs in the case of TtAgo. RsAgo binds plasmid DNA, which will be cleaved, yielding 22–24-nt DNA fragments. Binding of the guide-Ago complex to plasmid DNA furthermore possibly leads to an inhibition of plasmid transcription. The short fragments either stay bound to Argonaute (d) or interact with other RsAgo molecules to constitute DNA-RsAgo complexes and regulate plasmid transcription (e). Figure in part modified from Olovnikov et al. [8].