Staphylococcus aureus PhoU Homologs Regulate Persister Formation and Virulence

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

doi:10.3389/fmicb.2020.00865

Staphylococcus aureus PhoU Homologs Regulate Persister Formation and Virulence

Front Microbiol. 2020 May 26:11:865. doi: 10.3389/fmicb.2020.00865. eCollection 2020.

Authors

Yongpeng Shang¹, Xiaofei Wang¹, Zhong Chen¹, Zhihui Lyu¹, Zhiwei Lin², Jinxin Zheng², Yang Wu¹, Qiwen Deng², Zhijian Yu², Ying Zhang³, Di Qu¹

Affiliations

¹ Key Laboratory of Medical Molecular Virology of MOE and MOH, Department of Medical Microbiology and Parasitology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
² Department of Infectious Diseases and Shenzhen Key Lab for Endogenous Infection, Union Shenzhen Hospital, Huazhong University of Science and Technology, Shenzhen, China.
³ Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States.

Abstract

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 Staphylococcus aureus is closely correlated with persister formation and virulence factors. The functions of two PhoU homologs, PhoU1 and PhoU2, in S. aureus are unclear yet. In this study, single- and double-deletion mutants of phoU1 and phoU2 were generated in strain USA500 2395. The ΔphoU1 or ΔphoU2 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 ΔphoU2 mutants. Transcriptome analysis revealed that 573 or 285 genes were differentially expressed by at least 2.0-fold in the ΔphoU1 or ΔphoU2 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 (sarA, rot), and the two-component signal transduction system (saeS). Correspondingly, the deletion of the phoU1 or phoU2 resulted in increased levels of intracellular pyruvate and ATP. Deletion of the phoU2, but not the phoU1, resulted in the up-regulation of inorganic phosphate transport genes and increased levels of intracellular inorganic polyphosphate. In conclusion, both PhoU1 and PhoU2 in S. aureus 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 S. aureus are different from what we have previously found in Staphylococcus epidermis, where only PhoU2 regulates biofilm and persister formation. The different functions of PhoU homologs between the two species of Staphylococcus warrant further investigation.

Keywords: ATP; PhoU homolog; Staphylococcus aureus; persisters; phosphate metabolism; virulence.