Proteomics and Transcriptomics Uncover Key Processes for Elasnin Tolerance in Methicillin-Resistant Staphylococcus aureus

Abstract

Besides the excellent antibiofilm properties of elasnin, we discovered that it can also kill growing methicillin-resistant Staphylococcus aureus (MRSA) planktonic cells. We subjected MRSA cells to an in vitro evolution experiment, and the resulting evolved strains exhibited increased elasnin tolerance, reduced growth rate, loss of pigmentation, an increased proportion of small-colony formation, and they became more sensitive toward daptomycin and lysostaphin.

Elasnin Effectively Eradicates Daptomycin-Resistant Methicillin-Resistant Staphylococcus aureus Biofilms

“…Therefore, we were interested in seeing how elasnin affects a daptomycin-resistant MRSA (DAP R ) strain, which has membrane and cell-wall modifications due to the mutation it possessed (T345A gain-of-function in the mprF gene), and also lower biofilm formation compared to the WT strain ( 16 ). Our recent transcriptomic study has also shown that elasnin treatment led to a 10-fold downregulation in the expression of mprF gene on MRSA planktonic cells, the gene that was mutated in the DAP R strain ( 8 ).…”

“…It was reported that elasnin interfered with cell division and cell wall biosynthesis in both planktonic culture and biofilms ( 7 , 8 ). Therefore, we were interested in seeing how elasnin affects a daptomycin-resistant MRSA (DAP R ) strain, which has membrane and cell-wall modifications due to the mutation it possessed (T345A gain-of-function in the mprF gene), and also lower biofilm formation compared to the WT strain ( 16 ).…”

“…The elasnin was prepared according to a previously described protocol ( 5 , 8 ). Briefly, Streptomyces mobaraensis DSM 40847 was incubated for 5 days, and the culture broth was extracted with ethyl acetate.…”

“…The subsequent processing of the samples follows the same protocol from our previous study ( 8 ). Briefly, the cell pellet was suspended in 350 μL of lysis buffer (8M Urea, 50 mM Tris-HCl pH 8.0), frozen in liquid nitrogen, and sonicated for 15 min.…”

“…Since elasnin’s main mode of action is by disrupting the biofilm matrix and interfering with the cell division process, it has limited ability to kill biofilm or stationary phase cells ( 7 ). However, the resulting elasnin-treated biofilm cells were shown to exhibit cell wall defects and became more sensitive to β-lactams such as penicillin G. Follow-up analysis showed that although elasnin could barely kill non-growing stationary phase or biofilm cells upon prolonged treatment, it exhibited antibacterial activity against growing S. aureus planktonic cells, albeit with slow killing kinetics ( 8 ).…”