Disease relevance of hemB

• An increased demand for cytochromes is associated with symbiotic development and microaerobic metabolism in the bacterium Bradyrhizobium japonicum, and evidence suggests that hemB, rather than hemA, is the first essential bacterial heme synthesis gene in symbiosis with soybean [1].

High impact information on hemB

• Cultures of the hemB* strain KPZn3 had Zn(2+)-dependent ALA dehydratase activity that functioned in vivo as discerned by its heme prototrophy and expression of wild type levels of cellular hemes [2].
• B. japonicum strains were constructed that contained a single copy of either hemB or the altered gene hemB* integrated into the genome of a hemB- mutant [2].
• Oxygen limitation resulted in a greater-than-10-fold increase in the rate of hemB mRNA synthesis as determined by transcriptional runoff experiments, whereas hemH transcription was unaffected by the O2 status [1].
• Unlike the expression in parent strain I110, hemB expression was not affected by O2 in the fixJ strain 7360, and O2-limited cultures of the mutant contained quantities of hemB mRNA and protein that were comparable to uninduced levels found in aerobic cells [1].
• FixJ is a key transcriptional regulator that mediates O2-dependent differentiation in rhizobia, and therefore hemB expression is under developmental control [1].

Associations of hemB with chemical compounds

• Thus, hemB is a regulated gene in B. japonicum and is transcriptionally controlled by O2 [1].

References