The enzyme involved in transcription is RNA polymerase. This enzyme synthesizes RNA by using a single-stranded DNA template to form a complementary RNA strand. RNA polymerase catalyzes the formation of phosphodiester bonds between nucleotides, extending the RNA chain in the 5′ to 3′ direction
. In prokaryotes, a single RNA polymerase performs transcription of all types of RNA. In eukaryotes, there are three types of RNA polymerases with distinct functions:
- RNA polymerase I transcribes ribosomal RNA (rRNA) genes.
- RNA polymerase II transcribes protein-coding genes into messenger RNA (mRNA) and some small RNAs.
- RNA polymerase III transcribes transfer RNA (tRNA) and some small RNAs
RNA polymerase II is the primary enzyme responsible for transcribing genes that encode proteins in eukaryotic cells and requires additional proteins called general transcription factors to initiate transcription
. Thus, RNA polymerase is the central enzyme in transcription, responsible for reading the DNA template and synthesizing the corresponding RNA molecule.
