Responses in the expression of extracellular proteins in methicillin-resistant Staphylococcus aureus treated with rhodomyrtone

Abstract

Rhodomyrtone from a medicinal plant species, Rhodomyrtus tomentosa, is a challenged effective agent against Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA). The present study was undertaken to provide insight into MRSA extracellular protein expression following rhodomyrtone treatment. Secreteomic approach was performed on a representative clinical MRSA isolate exposing to subinhibitory concentration rhodomyrtone (0.174 μg/ml). The identified extracellular proteins of a response of MRSA to rhodomyrtone treated condition were both suppressed and overexpressed. Staphylococcal antigenic proteins, immunodominant antigen A (IsaA) and staphylococcal secretory antigen (SsaA) involved in cell wall hydrolysis were downregulated after the treatment. The results suggested that rhodomyrtone may interfere with WalK/WalR (YycG/YycF) system. Other enzymes such as lipase precursor and another lipase, glycerophosphoryl diester phosphodiesterase, were absent. In contrast, cytoplasmic proteins such as SpoVG and glycerol phosphate lipoteichoic acid synthase, and ribosomal proteins were found in the treated sample. Appearance of several cytoplasmic proteins in the treated culture supernatant revealed that the bacterial cell wall biosynthesis was disturbed. This finding provides a proteomic mapping of extracellular proteins after rhodomytone treatment. Extensive investigation is required for this natural compound as it has a great potency as an alternative anti-MRSA drug.

Antibacterial Activity ofRhodomyrtus tomentosa(Aiton) Hassk. Leaf Extract against Clinical Isolates ofStreptococcus pyogenes

“…Significant antibacterial activities of rhodomyrtone against many Gram-positive bacteria have been documented [18, 34]. Although the previous researches have attempted to explain the actions of rhodomyrtone [35–37], its antibacterial mechanisms of action are still unclear. Therefore, the development of this compound as a new lead drug needs more information and researches on its modes of action.…”

2-D GEL ELECTROPHORESIS MAP OF METHICILLIN-RESISTANT <i>STAPHYLOCOCCUS AUREUS</i> TREATED WITH <i>QUERCUS INFECTORIA</i> GALL EXTRACT

“…Cho et al (2008) demonstrated that tea polyphenol can differentially induced the expression of 3 proteins in MRSA whereas Sianglum et al (2011) on the other hand, reported that out of a total of 203 spots in common between the treated and untreated protein expression profiles, 18 were present only in rhodomyrtone-treated MRSA. A study of the expression of extracellular proteins by Visutti et al (2011) revealed that the identification of 4 amino acid sequences from 21 protein spots from the rhodomyrtone-treated MRSA were predicted as signal peptides sequences. …”

Antibacterial mechanisms of rhodomyrtone against important hospital-acquired antibiotic-resistant pathogenic bacteria

“…Similarly, Limsuwan et al (2009) reported that rhodomyrtone exhibited no bacteriolytic activity against Streptococcus mutans. In addition, proteome studies showed that rhodomyrtone at a subinhibitory concentration (0.174 mg ml 21 ) suppressed the expression of extracellular proteins of MRSA involved in cell wall hydrolysis such as staphylococcal secretory antigen (Visutthi et al, 2011). In contrast, close observation by transmission electron microscope in a parallel study on cellular proteomic analysis illustrated that some cell lysis occurred in rhodomyrtone-treated MRSA cells (Sianglum et al, 2011).…”