The Iron control element, acting in positive and negative control of iron-regulated Bradyrhizobium japonicum genes, is a target for the Irr protein.

ABSTRACT: Bradyrhizobium japonicum, the nitrogen-fixing soybean symbiont, possesses a heme uptake system encoded by the gene cluster hmuVUT-hmuR-exbBD-tonB. Transcription of the divergently oriented hmuT and hmuR genes was previously found to be induced by iron limitation and to depend on a 21-bp promoter-upstream iron control element (ICE). Here, we show by deletion analysis that the full-length ICE is needed for this type of positive control. Additional genes associated with ICE-like motifs were identified in the B. japonicum genome, of which bll6680 and blr7895 code for bacterioferritin and rubrerythrin homologs, respectively. Transcription start site mapping revealed that their ICEs directly overlap with either the -10 promoter region or the transcription initiation site, suggesting an involveme

SUBMITTER: Rudolph G 

PROVIDER: S-EPMC1347296 | biostudies-literature | 2006 Jan

REPOSITORIES: biostudies-literature