GlmS plays a key role in the virulence factor expression and biofilm formation ability of Staphylococcus aureus promoted by advanced glycation end products

ABSTRACT

Staphylococcus aureus (S. aureus) is well known for its biofilm formation ability and is responsible for serious, chronic refractory infections worldwide. We previously demonstrated that advanced glycation end products (AGEs), a hallmark of chronic hyperglycaemia in diabetic tissues, enhanced biofilm formation by promoting eDNA release via sigB upregulation in S. aureus, contributing to the high morbidity and mortality of patients presenting a diabetic foot ulcer infection. However, the exact regulatory network has not been completely described. Here, we used pull-down assay and LC-MS/MS to identify the GlmS as a candidate regulator of sigB in S. aureus stimulated by AGEs. Dual-luciferase assays and electrophoretic mobility shift assays (EMSAs) revealed that GlmS directly upregulated the transcriptional activity of sigB. We constructed NCTC 8325 ∆glmS for further validation. qRT-PCR analysis revealed that AGEs promoted both glmS and sigB expression in the NCTC 8325 strain but had no effect on NCTC 8325 ∆glmS. NCTC 8325 ∆glmS showed a significant attenuation in biofilm formation and virulence factor expression, accompanied by a decrease in sigB expression, even under AGE stimulation. All of the changes, including pigment deficiency, decreased haemolysis ability, downregulation of hla and hld expression, and less and sparser biofilms, indicated that sigB and biofilm formation ability no longer responded to AGEs in NCTC 8325 ∆glmS. Our data extend the understanding of GlmS in the global regulatory network of S. aureus and demonstrate a new mechanism by which AGEs can upregulate GlmS, which directly regulates sigB and plays a significant role in mediating biofilm formation and virulence factor expression.

KEYWORDS:

• Staphylococcus aureus
• advanced glycation end products
• virulence factor expression
• biofilm formation
• GlmS-sigB regulatory axis

Acknowledgements

The authors would like to thank the technical staff of the Nanhai Translational Innovation Center of Precision Immunology of Sun Yat-sen Memorial for their excellent technical assistance.

Disclosure statement

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

Author contributions

LJN and XYX were responsible for designing experiments and writing the manuscript. RS, HL, LSH, YWD, and XYL participated in analysis of experimental results and drawing tables and figures. LJN, RS, XXL, XFZ, and YLW were responsible for the experiments. ZHD participated in literature searching and manuscript modification. All authors have read and approved the final manuscript. Informed consent was obtained from all individual participants included in the study.

Data availability statement

The data generated during the study are available at the repository figshare at https://doi.org/10.6084/m9.figshare.25627158.v1. The raw data of mass spectrometry proteomics data have been deposited to the ProteomeXchange repository at http://www.ebi.ac.uk/pride, with the dataset identifier PXD046076.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/21505594.2024.2352476

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China [82002203]; Basic and Applied Basic Research Foundation of Guangdong Province [2023A1515010089].