Spectroscopic, catalytic and binding properties of Bacillus subtilis NO synthase-like protein: Comparison with other bacterial and mammalian NO synthases

Genome sequencing has shown the presence of genes coding for NO-synthase (NOS)-like proteins in bacteria. The roles and properties of these proteins remain unclear. UV–visible spectroscopy was used to characterize the recombinant NOS-like protein from Bacillus subtilis (bsNOS) in its ferric and ferrous states in the presence of various FeIII- and FeII-heme-ligands and of a series of l-arginine (l-arg) analogs. BsNOS exhibited several spectroscopic and binding properties in common with Bacillus anthracis NOS (baNOS) that were clearly different from those of tetrahydrobiopterin (H4B)-free mammalian NOS oxygenase domains (mNOSoxys) and of Staphylococcus aureus NOS (saNOS). Interestingly, bsNOS and baNOS that do not contain H4B exhibited properties much closer to those of H4B-containing mNOSoxys. Moreover, bsNOS was found to efficiently catalyze the oxidation of l-arginine into l-citrulline by H2O2, whereas H4B-free mNOSoxys exhibited low activities for this reaction.

Spectroscopic, catalytic and binding properties of Bacillus subtilis NO synthase-like protein.Figure optionsDownload as PowerPoint slideHighlights
► Bacillus subtilis NOS binds FeIII- and FeII-heme-ligands and l-arginine analogs.
► BsNOS exhibits binding properties in common with Bacillus anthracis NOS.
► BsNOS exhibits binding properties clearly different from those of H4B-free mammalian NOS.
► BsNOS efficiently catalyzes the oxidation of l-arginine into l-citrulline by H2O2.