The NusA:RNA polymerase ratio is increased at sites of rRNA synthesis in Bacillus subtilis.
Bacterial RNA polymerases (RNAPs) are capable of producing full-length transcripts in the absence of additional factors using in vitro assays. However, in vivo RNAP can become stalled during the elongation phase of transcription due to the presence of various sequence motifs. Subsequently, a host of elongation factors are required to modulate the activity of RNAP. NusA, the most intensively studied elongation factor, plays a role in increasing RNAP pausing and termination. Conversely, it is also important in transcription of rRNA where it functions as an anti-termination factor, helping to ensure only full-length transcripts are produced. Here we show that NusA is closely associated with RNAP within the bacterial nucleoid and that it is preferentially recruited to sites of rRNA synthesis. In vivo and in vitro analyses indicate this results in a change in stoichiometry of NusA:RNAP from 1:1 to approximately 2:1 at the subcellular sites of rRNA synthesis. A model is presented showing how the ratio of NusA:RNAP could affect the activity of the elongation complex so that it functions as an anti-terminator complex during rRNA synthesis.
School of Environmental and Life Sciences, Biological Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.
Karen M
KM
Davies
Amy J
AJ
Dedman
Stephanie
S
van Horck
Peter J
PJ
Lewis
D001412:Bacillus subtilis / Q000201:enzymology / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000737:chemistry; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D010445:Peptide Elongation Factors / Q000032:analysis* / Q000502:physiology; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D014157:Transcription Factors / Q000032:analysis* / Q000502:physiology; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010445:Peptide Elongation Factors; D012335:RNA, Ribosomal; D014157:Transcription Factors; D035602:Transcriptional Elongation Factors; C068727:nusA protein, E coli; D012321:DNA-Directed RNA Polymerases