Figure 4. Two Models for the Role of EGO-1 in Silencing Unpaired DNA during Meiosis.
(A and B) Unpaired DNA (A) associates with and (B) is transcribed by a DNA-dependent RNA polymerase that is not active on paired DNA. HIM-17 may participate in this process.
(C) EGO-1 binds to the RNA and recruits chromatin modifiers, e.g., histone methyltransferase (HMTase), to the region. RHA-1 may function in an RdRC-like complex with EGO-1 at this step. HMTase may directly bind to EGO-1 for its recruitment. Alternatively, EGO-1 generates dsRNA, which then triggers assembly of a RITS-like complex. RITS-like activity then recruits HMTase.
(D) The end result of the EGO-1-RNA association is accumulation of H3K9me2 modifications preferentially on the unpaired DNA.