Plastid-encoded RNA polymerase (PEP) (PEP)

The Plastid-encoded RNA polymerase (PEP) is a large, multisubunit enzyme complex that serves as the primary transcriptional machinery for the chloroplast genome in plants and algae (Börner et al., 2015). It is structurally and functionally related to the bacterial RNA polymerase core enzyme, typically composed of four core subunits (alpha, beta, beta', and beta'') encoded by the plastid rpo genes (Pfannschmidt et al., 2015). PEP is responsible for transcribing genes essential for photosynthesis, such as those encoding components of the photosystems and the large subunit of RuBisCO. In addition to its role in plants, PEP-like polymerases are found in the apicoplast of apicomplexan parasites like Plasmodium falciparum, making it a significant target for developing anti-malarial drugs (Dahl & Rosenthal, 2008). Because of its prokaryotic origins, PEP is sensitive to inhibitors like rifampicin and tagetitoxin, which do not typically affect the single-subunit RNA polymerases found in human mitochondria. Consequently, PEP represents a unique target for both herbicidal applications and selective anti-parasitic therapy.

Other names

Chloroplast multisubunit RNA polymerasePlastid RNA polymerasePEPDNA-directed RNA polymerase (plastid-encoded)Prokaryotic-type plastid RNA polymerase

Inhibition of DNA-directed RNA polymerase activity by binding to the beta subunit and blocking the path of the nascent RNA transcript.