NusG is an intrinsic transcription termination factor that stimulates motility and coordinates gene expression with NusA.

Abstract

NusA and NusG are transcription factors that stimulate RNA polymerase pausing in <i>Bacillus subtilis</i>. While NusA was known to function as an intrinsic termination factor in <i>B. subtilis</i>, the role of NusG in this process was unknown. To examine the individual and combinatorial roles that NusA and NusG play in intrinsic termination, Term-seq was conducted in wild type, NusA depletion, Δ<i>nusG</i>, and NusA depletion Δ<i>nusG</i> strains. We determined that NusG functions as an intrinsic termination factor that works alone and cooperatively with NusA to facilitate termination at 88% of the 1400 identified intrinsic terminators. Our results indicate that NusG stimulates a sequence-specific pause that assists in the completion of suboptimal terminator hairpins with weak terminal A-U and G-U base pairs at the bottom of the stem. Loss of NusA and NusG leads to global misregulation of gene expression and loss of NusG results in flagella and swimming motility defects.