RNA polymerases are multi-subunit proteins that transcribe genes encoded in DNA to messenger RNA (mRNA). The mRNA is then translated into protein at the ribosome.
In a recent publication in Protein Science, iCOOL affiliate Claudia Alvarez Carreno, Co-I Anton Petrov, and PI Loren Williams describe, for the first time, the insertion of blocks of conserved sequence and structure into the catalytic subunits of RNA polymerase.
Interestingly, although the insertions, dubbed BEAN and HABAS, each represent a group of orthologs (descending from a common ancestor), their insertion positions within the catalytic subunits vary. Additionally, the BEAN insertion is found in the archaeal version of universally conserved ribosomal protein uL10 but not the bacterial version. Taken together, the results suggest discrete episodes of domain insertion around or after the last bacterial common ancestor.
Insertion of BEAN in the RNAP-β subunit of RNA polymerase.