An RNA polymerase from the ocean improves in vitro RNA synthesis (560.1)

Abstract

Phages in the ocean harbor the greatest diversity of protein on the earth. Since a large portion of these proteins must play roles in nucleic acids metabolism, one would expect numerous novel mechanisms underlying the fundamental processes including transcription, DNA replication, and recombination and thus abundant molecular reagents therein. We recently characterized the single subunit RNA polymerase from marine cyanophage Syn5 and identified its promoter sequence. This marine enzyme catalyzes RNA synthesis over a wide range of temperature and salinity. Its processivity is greater than 30,000 nt without any significant intermediate products. Most important, Syn5 RNA polymerase produces precise run‐off transcripts with homogeneous 3’ termini. The enzyme predominantly used for in vitro run‐off RNA synthesis‐T7 RNA polymerase synthesizes, in addition to run‐off products of precise length, transcripts with an additional non‐base‐paired nucleotide at the 3’‐terminus (N+1 product). Therefore, the enzyme is advantageous for the production of RNAs that require precise 3’‐termini, such as tRNAs and RNA fragments that are used for subsequent assembly.