Plastids have an interesting transcription machinery that makes it possible to study the interplay of mono- and multisubunit RNA polymerases (RNAPs) during intricate organelle biogenesis, requiring the concerted expression of genes located in different compartments of the cell. The past decade has been marked by a breakthrough in studies of chloroplast RNAPs. Nucleus-encoded monosubunit RNAP (NEP) was discovered; a nuclear gene family was found to code for σ subunits of plastid-encoded multisubunit RNAP (PEP); mutants knocked-out in PEP subunit genes were obtained; a reorganization of PEP was observed during plastid biogenesis; and a hypothesis was advanced to describe the division of functions between NEP and PEP. The review considers recent data on the organization, functions, and evolution of plastid RNAPs.
- Gene expression
- RNA polymerase