RNA polymerase IV
RNA polymerase IV is an enzyme which synthesizes small interfering RNA (siRNA) in plants.[1] Polymerase IV is specific to plants genomes and is required for the synthesis of over 90% of 24-nt heterochromatic siRNA. [2]
Function
RNA polymerase silences the transposons and repetitive DNA in the siRNA pathway.[1] The siRNA plays a major role in defending the genome against the invading viruses and transposable elements by RNA directed DNA methylation. [2]
Polymerase IV and ROS1 demethylase unlocks and recondenses the 5S rDNA chromatin, which is present in seed and used for the development of adult features in plants. [3] Polymerase IV is involved in setting the methylation patterns in the 5S genes during plant maturation. [3]
In arabidopsis polymerase IV works with binding protein DCL3 and a RNA polymerase II RDR2 in a silencing pathway which Polymerase IV would produce RNA, which is changed to dsRNA by RDR2 then converted to siRNA by DCL3.[1]
