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The ClpX protein of Bacillus subtilis indirectly influences RNA polymerase holoenzyme composition and directly stimulates σ H ‐dependent transcription
Author(s) -
Liu Jiajian,
Zuber Peter
Publication year - 2000
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2000.02053.x
Subject(s) - biology , bacillus subtilis , transcription (linguistics) , rna polymerase , polymerase , rna , microbiology and biotechnology , transcription factor ii d , biochemistry , dna , bacteria , genetics , gene , linguistics , philosophy
In Bacillus subtilis , several processes associated with the onset of stationary phase, including the initiation of sporulation, require the activity of the minor σ H form of RNA polymerase (RNAP). The induction of σ H ‐dependent gene transcription requires the regulatory ATPase, ClpX. The ClpX‐dependent post‐exponential increase in σ H activity is not dependent on the activator of sporulation gene expression, Spo0A. By determining the level of σ H and σ A in whole‐cell extracts and RNAP preparations, evidence is presented that clpX does not influence the concentration of sigma subunits, but is required for the stationary phase reduction in σ A ‐RNAP holoenzyme. This is probably an indirect consequence of ClpX activity, because the ClpX‐dependent decrease in σ A ‐RNAP concentration does not occur in a spo0A abrB mutant. The addition of ClpX to in vitro transcription reactions resulted in the stimulation of RNAP holoenzyme activity, but σ H ‐RNAP was observed to be more sensitive to ClpX‐dependent stimulation than σ A ‐RNAP. No difference in transcriptional activity was observed in single‐cycle in vitro transcription reactions, suggesting that ClpX acted at a step in transcription initiation after closed‐ and open‐promoter complex formation. ClpX is proposed to function indirectly in the displacement of σ A from core RNAP and to act directly in the stimulation of σ H ‐dependent transcription in sporulating B. subtilis cells.