Molybdopterin biosynthesis pathway contributes to the regulation of SaeRS two-component system by ClpP in Staphylococcus aureus

ABSTRACT

In Staphylococcus aureus, the SaeRS two-component system is essential for the bacterium’s hemolytic activity and virulence. The Newman strain of S. aureus contains a variant of SaeS sensor kinase, SaeS L18P. Previously, we showed that, in the strain Newman, SaeS L18P is degraded by the membrane-bound protease FtsH. Intriguingly, the knockout mutation of clpP, encoding the cytoplasmic protease ClpP, greatly reduces the expression of SaeS L18P. Here, we report that, in the strain Newman, the positive regulatory role of ClpP on the SaeS L18P expression is due to its destabilizing effect on FtsH and degradation of MoeA, a molybdopterin biosynthesis protein. Although the transcription of ftsH was not affected by ClpP, the expression level of FtsH was increased in the clpP mutant. The destabilizing effect appears to be indirect because ClpXP did not directly degrade FtsH in an in vitro assay. Through transposon mutagenesis, we found out that the moeA gene, encoding the molybdopterin biosynthesis protein A, suppresses the hemolytic activity of S. aureus along with the transcription and expression of SaeS L18P. In a proteolysis assay, ClpXP directly degraded MoeA, demonstrating that MoeA is a substrate of the protease. In a murine bloodstream infection model, the moeA mutant displayed reduced virulence and lower survival compared with the WT strain. Based on these results, we concluded that ClpP positively controls the expression of SaeS L18P in an FtsH and MoeA-dependent manner, and the physiological role of MoeA outweighs its suppressive effect on the SaeRS TCS during infection.

KEYWORDS:

• Staphylococcus aureus
• proteolysis system
• SaeS
• MoeA
• degradation

Acknowledgments

The authors would like to acknowledge Cai-Guang Yang from the Chinese Academy of Sciences for the gift of the pET28b plasmids of ClpP and ClpX.

Author contributions

QL, TB, and ML conceived the study. NZ, YW, JL, ZY, YJ, HW, and MA performed experiments. QL, TB, ML, and HW analyzed the data. QL, TB,and ML drafted the manuscript. NZ, YW, JL, ZY, YJ, HW, MA, QL, TB and ML revised and approved the manuscript.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was supported by the National Natural Science Foundation of China [grant 82072235, 81772139, QL], Shanghai Rising-Star Program [20QA1405900], the Shanghai Committee of Science and Technology, China [grant 20ZR1432800], Shanghai Shuguang Program 21SG17 to QL and NIH [AI14379] to TB; National Institutes of Health [AI143792]; Science and Technology Commission of Shanghai Municipality [20ZR1432800].