A. Wegrzyn et al., Differential inhibition of transcription from sigma(70)- and sigma(32)-dependent promoters by rifampicin, FEBS LETTER, 440(1-2), 1998, pp. 172-174
Rifampicin is an antibiotic which binds to the beta subunit of prokaryotic
RNA polymerases and prevents initiation of transcription, It was found prev
iously that production of heat shock proteins in Escherichia coli cells aft
er a shift from 30 degrees C to 43 degrees C is not completely inhibited by
this antibiotic, Here we demonstrate that while activity of a p(L)-lacZ fu
sion (p(L) is a sigma(70)-dependent promoter) in E. coli cells is strongly
inhibited by rifampicin, a p(groE)-lacZ fusion, whose activity is dependent
on the sigma(32) factor, retains significant residual activity even at rel
atively high rifampicin concentrations. Differential sensitivity to this an
tibiotic of RNA polymerase holoenzymes containing either the sigma(70) or t
he sigma(32) subunit was confirmed in vitro, Since the effects of an antibi
otic that binds to the beta subunit can be modulated by the presence of eit
her the sigma(70) or the sigma(32) subunit in the holoenzyme, it is temptin
g to speculate that binding of various a factors to the core of RNA polymer
ase results in different conformations of particular holoenzymes, including
changes in the core enzyme. (C) 1998 Federation of European Biochemical So
cieties.