CotA of Bacillus subtilis is a copper-dependent laccase

The spore coat protein CotA of Bacillus subtilis, displays similarities with multicopper oxidases, including manganese oxidases and laccases. B. subtilis is able to oxidize manganese, but neither CotA nor other sporulation proteins are involved. We demonstrate that CotA is a laccase. Syringaldazine, a specific substrate of laccases, reacted with wild-type spores but not with Delta cotA spores. CotA may participate in the biosynthesis of the brown spore pigment, which appears to be a melanin-like product and to protect against UV light.