Proteomic analysis of the proteins released from Staphylococcus aureus following exposure to Ag(I)

Abstract

a b s t r a c tThe silver ion (Ag(I)) has well established antimicrobial properties and is widely used in a variety of antibacterial ointments and plasters for the control of wound infections. Wounds are frequently colonised by the bacterium Staphylococcus aureus and the aim of the work presented here was to establish how S. aureus responded following exposure to Ag(I). Exposure of S. aureus to Ag(I) resulted in the release of a range of proteins from cells. Analysis of proteins released revealed a number of proteins associated with the stress response (e.g. alkaline shock protein, methionine sulfoxide reductase), virulence (e.g. signal transduction protein) and metabolism (e.g. lipase, acetate kinase, phosphoglycerate mutase). The release of toxins (e.g. a-hemolysin, bifunctional autolysin, leucocidin F) was decreased. These results indicated that, while silver is a potent antimicrobial agent, exposure of S. aureus to this metal results in the release of a variety of proteins from the cell. Many of the proteins showing increased release were antigenic and would have the potential to induce an inflammatory response at the site of infection and thus delay healing.

Changes in the Cytoplasmic Composition of Amino Acids and Proteins Observed in Staphylococcus aureus during Growth under Variable Growth Conditions Representative of the Human Wound Site

“…It has already been established that some ribosomal proteins are not important in the translation apparatus as some such as S1, S21, S22, S31e, and L25 do not exist in all bacteria [ 49 ].It is also known that the deletion of some of these ribosomal genes did not affect the viability of the cells [ 18 , 49 – 51 ]. It has been suggested that ribosomal proteins have an extra-ribosomal role as they have been found amongst the surface and secreted proteins of cells [ 51 – 53 ] but the certain roles of these secreted ribosomal proteins remain unclear. It is therefore proposed that certain members of the suite of ribosomal proteins may be secreted to the surface of the cell or into the external environment as a defensive mechanism in response to external challenges from host immune system, antibiotics and changing environmental conditions.…”

Analysis of Cytoplasmic and Secreted Proteins of Staphylococcus aureus Revealed Adaptive Metabolic Homeostasis in Response to Changes in the Environmental Conditions Representative of the Human Wound Site

“…The elevated intensities of a certain number of proteins compared with the constant secretion of some proteins suggested that these proteins may play specific roles in the adaptation of this bacterium to the applied conditions. In earlier work, S. aureus exhibited different secretome profiles in response to silver ions [ 3 ]. It is reasonable to hypothesize that these proteins may also have a role in neutralizing the surrounding environments.…”

“…A significant reduction in the secretion of enolase and immunodominant antigen staphylococcal A was noted following the exposure to environmental challenges. It has been shown that proteins involved in pathogenicity and metabolism were substantially decreased in response to silver ions [ 3 ] suggesting that the bacterium down regulated its metabolism and virulence factors to focus on surviving harsher conditions under nutrient limitations with accumulated waste products. The secretion of lipase 1 and 2 in the current study was more by the cells growing with the addition of NaCl compared with the cells grown without salt.…”

“…However, the exact mechanism that enables the switch from a commensal to a pathogenic lifestyle is unclear [ 2 ]. The threat of this bacterium lies in its remarkable and rapid capacity to sense environmental signals and modulate the cellular responses; this is the major challenge for clinicians and scientists [ 3 , 4 , 5 ]. The capacity of S. aureus to adapt to fluctuations in environmental conditions was proposed to be due to its ability to induce considerable changes in cytoplasmic metabolites and proteins [ 4 , 6 , 7 ].…”

Phytochemical-mediated Protein Expression Profiling and the Potential Applications in Therapeutic Drug Target Identifications

“…The situation is grimmer if taking into account the decreasing antibiotic candidate in the pharmaceutical development pipeline. In view of this situation, increasing researches are aiming toward the identification of potentially useful antibacterial compounds or materials, especially those which specifically target critical enzymes in bacterial pathways (Machowski et al, 2014;Smith et al, 2013).…”