AUTHOR=Gao Peng , Wang Yanli , Villanueva Iván , Ho Pak Leung , Davies Julian , Kao Richard Yi Tsun 

TITLE=Construction of a Multiplex Promoter Reporter Platform to Monitor Staphylococcus aureus Virulence Gene Expression and the Identification of Usnic Acid as a Potent Suppressor of psm Gene Expression

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01344

DOI=10.3389/fmicb.2016.01344

ISSN=1664-302X

ABSTRACT=<p>As antibiotic resistance becomes phenomenal, alternative therapeutic strategies for bacterial infections such as anti-virulence treatments have been advocated. We have constructed a total of 20 <italic>gfp</italic>-<italic>luxABCDE</italic> dual-reporter plasmids with selected promoters from <italic>S. aureus</italic> virulence-associated genes. The plasmids were introduced into various <italic>S. aureus</italic> strains to establish a <italic>gfp-lux</italic> based multiplex promoter reporter platform for monitoring <italic>S. aureus</italic> virulence gene expressions in real time to identify factors or compounds that may perturb virulence of <italic>S. aureus</italic>. The gene expression profiles monitored by luminescence correlated well with qRT-PCR results and extrinsic factors including carbon dioxide and some antibiotics were shown to suppress or induce the expression of virulence factors in this platform. Using this platform, sub-inhibitory ampicillin was shown to be a potent inducer for the expression of many virulence factors in <italic>S. aureus</italic>. Bacterial adherence and invasion assays using mammalian cells were employed to measure <italic>S. aureus</italic> virulence induced by ampicillin. The platform was used for screening of natural extracts that perturb the virulence of <italic>S. aureus</italic> and usnic acid was identified to be a potent repressor for the expression of <italic>psm</italic>.</p>