Premium
Functional analysis of the Helicobacter pylori principal sigma subunit of RNA polymerase reveals that the spacer region is important for efficient transcription
Author(s) -
Beier Dagmar,
Spohn Gunther,
Rappuoli Rino,
Scarlato Vincenzo
Publication year - 1998
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.1365-2958.1998.01043.x
Subject(s) - biology , rna polymerase , sigma factor , specificity factor , transcription (linguistics) , promoter , gene , genetics , polymerase , nucleic acid sequence , protein subunit , bacillus subtilis , microbiology and biotechnology , homology (biology) , escherichia coli , gene expression , bacteria , linguistics , philosophy
We have cloned the rpoD gene encoding the principal sigma (σ) factor of Helicobacter pylori . The deduced amino acid sequence reveals a predicted polypeptide of 676 residues that has amino acid homology with the principal σ factors of a number of divergent prokaryotes. We have designated this factor σ 80 . Amino acid sequence analysis suggests that region 1.1 is missing in σ 80 and that a region with homology to a regulatory protein from Bacillus subtilis phage SPO1 is present. Genetic studies have indicated that σ 80 is not compatible with the transcriptional machinery of Escherichia coli . However, in vitro σ 80 could be assembled into the E. coli RNA polymerase and could bind to E. coli and H. pylori promoters, suggesting that the σ 80 ‐containing RNA polymerase has the same stoichiometry as the native complex. By exchanging protein domains between E. coli and H. pylori σ factors, we demonstrate that the σ 80 domain inhibiting transcription from E. coli promoters is confined within the non‐conserved spacer region, implying that the spacer region of prokaryotic primary σ factors plays an important role in the process of transcription. Consistent with its restricted niche and with the availability of a very restricted number of transcriptional regulators, H. pylori may have evolved a spacer region of the σ factor to modulate total transcription and to quickly respond to microenvironmental changes.