Alpha-helix E of Spo0A is required for sigmaA- but not for sigmaH-dependent promoter activation in Bacillus subtilis.
At the onset of endospore formation in Bacillus subtilis, the DNA binding protein Spo0A activates transcription from two types of promoters. The first type includes the spoIIG and spoIIE promoters, which are used by sigma(A)-RNA polymerase, whereas the second type includes the spoIIA promoter, which is used by RNA polymerase containing the secondary sigma factor sigma(H). Previous genetic analyses have identified specific amino acids in alpha-helix E of Spo0A that are important for activation of Spo0A-dependent, sigma(A)-dependent promoters. However, these amino acids are not required for activation of the sigma(H)-dependent spoIIA promoter. We now report the effects of additional single-amino-acid substitutions and the effects of deletions in alpha-helix E. The effects of alanine substitutions revealed one new position (239) in Spo0A that appears to be specifically required for activation of the sigma(A)-dependent promoters. Based on the effects of a deletion mutation, we suggest that alpha-helix E in Spo0A is not directly involved in interaction with sigma(H)-RNA polymerase.
Kumar
Amrita
A
Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Brannigan
James A
JA
Moran
Charles P
CP
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D001483:Base Sequence; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D017433:Protein Structure, Secondary; D012808:Sigma Factor / Q000502:physiology*; D014157:Transcription Factors / Q000737:chemistry / Q000502:physiology*
D001426:Bacterial Proteins; C120328:SigH protein, bacteria; D012808:Sigma Factor; C080950:Spo0A protein, Bacillus subtilis; D014157:Transcription Factors