In depth analysis of the mechanism of action of metal-dependent sigma factors: characterization of CorE2 from Myxococcus xanthus

摘要: Extracytoplasmic function sigma factors represent the third pillar of signal-transduction mechanisms in bacteria. The variety stimuli they recognize and action use have allowed their classification into more than 50 groups. We characterized CorE2 from Myxococcus xanthus, which belongs to group ECF44 upregulates expression two genes when it is activated by cadmium zinc. Sigma this contain a Cys-rich domain (CRD) at C terminus essential for detecting metals. Point mutations six Cys residues CRD revealed contribution each residue activity. Some them are essential, while others either dispensable or only slightly affect activity protein. However, importantly, mutation Cys174 completely shifts specificity copper, indicating that arrangement determines metal specificity. Moreover, conserved CxC motif located between σ2 σ4.2 region has also been found be results presented here contribute our understanding mechanism metal-dependent help define new common features members regulators.