Regulation of the Helicobacter pylori Fe-S cluster synthesis protein NifS by iron, oxidative stress conditions, and fur.
Transcription of both chromosomal and extrachromosomally introduced nifS was regulated (up-expressed) by oxygen or by supplemental iron conditions. This up-expression was not observed in a fur mutant strain background or when an iron chelator was added. Iron-bound Fur (but not apo-Fur) recognized the nifS promoter, and Fur bound significantly farther upstream (-155 bp to -190 bp and -210 to -240 bp) in the promoter than documented Helicobacter pylori Fur binding regions. This binding was stronger than Fur recognition of the flgE or napA promoter and includes a Fur recognition sequence common to the H. pylori pfr and sodB upstream areas. Studies of Fur-regulated genes in H. pylori have indicated that apo-Fur acts as a repressor, but our results demonstrate that iron-bound Fur activates (nifS) transcription.
Alamuri
Praveen
P
Department of Microbiology, 527 Biological Sciences Bldg., The University of Georgia, Athens, GA 30602, USA.
Mehta
Nalini
N
Burk
Andrew
A
Maier
Robert J
RJ
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D016480:Helicobacter pylori / Q000187:drug effects / Q000502:physiology*; D007501:Iron / Q000494:pharmacology*; D007700:Kinetics; D009586:Nitrogen Fixation; D018384:Oxidative Stress; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D017931:DNA Primers; C080001:nifS protein, Bacteria; D007501:Iron