Eugenol targeting CrtM inhibits the biosynthesis of staphyloxanthin in <i>Staphylococcus aureus</i>
Jiang Chang, Bo Chen, Zeqian Du, Bowen Zhao, Jiahui Li, Ziyi Li, Arunachalam Kannappan, Ting Shi, Dong‐Qing Wei, Chunlei Shi
Abstract
<em>Staphylococcus aureus</em> is a serious foodborne pathogen threatening food safety and public health. Especially the emergence of methicillin-resistant <em>Staphylococcus aureus</em> (MRSA) increased the difficulty of <em>S. aureus</em> treatment. Staphyloxanthin is a crucial virulence factor of <em>S. aureus</em>. Blocking staphyloxanthin production could help the host immune system counteract the invading <em>S. aureus</em> cells. In this study, we first screened for staphyloxanthin inhibitors using a virtual screening method. The outcome of the virtual screening method resulted in the identification of eugenol (300 μg/mL), which significantly inhibits the staphyloxanthin production in <em>S. aureus</em> ATCC 29213, <em>S. aureus</em> Newman, MRSA ATCC 43300 and MRSA ATCC BAA1717 by 84.2%, 63.5%, 68.1%, and 79.5%, respectively. The outcome of the growth curve assay, field-emission scanning electron, and confocal laser scanning microscopy analyses confirmed that eugenol at the test concentration did not affect the morphology and growth of <em>S. aureus</em>. Moreover, the survival rate of <em>S. aureus</em> ATCC 29213 and MRSA ATCC 43300 under H<sub>2</sub>O<sub>2</sub> pressure decreased to 51.9% and 45.5% in the presence of eugenol, respectively. The quantitative RT-PCR and molecular simulation studies revealed that eugenol targets staphyloxanthin biosynthesis by downregulating the transcription of the <em>crtM</em> gene and inhibiting the activity of the CrtM enzyme. Taken together, we first determined that eugenol was a prominent compound for staphyloxanthin inhibitor to combat <em>S. aureus</em> especially MRSA infections.