RNA polymerase subunit H features a beta-ribbon motif within a novel fold that is present in archaea and eukaryotes.

Abstract The archaeal H and eukaryotic RPB5 RNA polymerase subunits are highly homologous and are likely to play a fundamental role in transcription that extends from archaea to humans. We report the structure of subunit H, in solution, from the archaeon Methanococcus jannaschii using multidimensional nuclear magnetic resonance. The structure reveals a novel fold containing a four-stranded mixed β sheet that is flanked on one side by three short helices. The dominant feature is β-ribbon motif, which presents a hydrophobic, basic surface, and defines a general RNA polymerase architectural scaffold.