AUTHOR=Shang Yongpeng , Wang Xiaofei , Chen Zhong , Lyu Zhihui , Lin Zhiwei , Zheng Jinxin , Wu Yang , Deng Qiwen , Yu Zhijian , Zhang Ying , Qu Di 

TITLE=Staphylococcus aureus PhoU Homologs Regulate Persister Formation and Virulence

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.00865

DOI=10.3389/fmicb.2020.00865

ISSN=1664-302X

ABSTRACT=<p>PhoU homologs are one of the determinant factors in the regulation of persister formation and phosphate metabolism in many bacterial species; however, the functions of PhoU homologs exhibit species-specific characteristics. The pathogenesis of <italic>Staphylococcus aureus</italic> is closely correlated with persister formation and virulence factors. The functions of two PhoU homologs, PhoU1 and PhoU2, in <italic>S. aureus</italic> are unclear yet. In this study, single- and double-deletion mutants of <italic>phoU1</italic> and <italic>phoU2</italic> were generated in strain USA500 2395. The Δ<italic>phoU1</italic> or Δ<italic>phoU2</italic> mutants displayed a change in persister formation and virulence compared to the parent strain; the persisters to vancomycin and levofloxacin were decreased at least 1,000-fold, and the number of intracellular bacteria surviving in the A549 cells for 24 h decreased to 82 or 85%. The α-hemolysin expression and activity were increased in the Δ<italic>phoU2</italic> mutants. Transcriptome analysis revealed that 573 or 285 genes were differentially expressed by at least 2.0-fold in the Δ<italic>phoU1</italic> or Δ<italic>phoU2</italic> mutant vs. the wild type. Genes involved in carbon and pyruvate metabolism were up-regulated, and virulence genes and virulence regulatory genes were down-regulated, including type VII secretion system, serine protease, leukocidin, global regulator (<italic>sarA</italic>, <italic>rot</italic>), and the two-component signal transduction system (<italic>saeS</italic>). Correspondingly, the deletion of the <italic>phoU1</italic> or <italic>phoU2</italic> resulted in increased levels of intracellular pyruvate and ATP. Deletion of the <italic>phoU2</italic>, but not the <italic>phoU1</italic>, resulted in the up-regulation of inorganic phosphate transport genes and increased levels of intracellular inorganic polyphosphate. In conclusion, both PhoU1 and PhoU2 in <italic>S. aureus</italic> regulate virulence by the down-regulation of multiple virulence factors (type VII secretion system, serine protease, and leucocidin) and the persister generation by hyperactive carbon metabolism accompanied by increasing intracellular ATP. The results in <italic>S. aureus</italic> are different from what we have previously found in <italic>Staphylococcus epidermis</italic>, where only PhoU2 regulates biofilm and persister formation. The different functions of PhoU homologs between the two species of <italic>Staphylococcus</italic> warrant further investigation.</p>