Open AccessPromoter selectivity ofEscherichia coliRNA polymerase: omega factor is responsible for the ppGpp sensitivity
Author(s) -
Kazuhiko Igarashi,
Nobuyuki Fujita,
Akira Ishihama
Publication year - 1989
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/17.21.8755
Subject(s) - rna polymerase , biology , sigma factor , microbiology and biotechnology , stringent response , polymerase , escherichia coli , transcription (linguistics) , rna , guanosine , rna polymerase i , rna dependent rna polymerase , rna polymerase ii , biochemistry , gene , gene expression , promoter , linguistics , philosophy
Transcription in vitro of stringently controlled Escherichia coli genes by purified RNA polymerase holoenzyme is inhibited by guanosine tetraphosphate (ppGpp). In order to examine possible role of omega factor in this ppGpp sensitivity, RNA polymerases with or without the omega factor were reconstituted and tested for their ppGpp sensitivity using an in vitro mixed transcription system. RNA polymerase lacking the omega factor was found virtually insensitive to ppGpp but the addition of a purified omega factor restored the ppGpp sensitivity of this omega-free RNA polymerase. These results raise a possibility that the omega factor is a regulatory protein of RNA polymerase and is involved in the ppGpp-mediated alteration of the promoter selectivity.