Staphylococcus aureus protein synthesis

Mineral oil [liquid paraffin) was also used for the formation of pre-polymerization droplets [Kempe and Kempe, 2006). Being chemically inert in nature, these liquids do not affect the non-covalent interactions in template-monomer complex when used as a dispersing medium. There are some recent reports utilizing suspension polymerization for MIP synthesis for Staphylococcus aureus protein A-imprinted polyacrylamide [Pan et al., 2009), Stlgmasterol MIP microspheres [Han et al., 2008), MIP hydrogels for the peptide hepcidin [Abbate et al., 2010) and Promethazine based MIPs [Alizadeh et al., 2012). 

Oxazolidinones are a new class of synthetic antimicrobial agents, which have activity against many important pathogens, including methicillin-resistant Staphylococcus aureus and others. Oxazolidinones (e.g. linezolid or eperezolid) inhibit bacterial protein synthesis by inhibiting the formation of the 70S initiation complex by binding to the 50S ribosomal subunit close to the interface with the 3OS subunit. 

These antibiotics are considered as a choice of last resort where every other antibiotic therapy has failed. The first and only commercially available oxazolidinone antibiotic is linezolid which was introduced in 2002. Its mechanism of action is inhibition of bacterial protein synthesis. It is available for intravenous administration and also has the advantage of having excellent oral bioavailability. Linezolid is used for the treatment of infections caused by multi-resistant bacteria including streptococcus and methicillin-resistant Staphylococcus aureus (MRS A). 

Mechanism of Action. Hie earliest studies on the mechanism of action of lincomycin showed that lincomycin had die immediate effect on Staphylococcus aureus of complete inhibition of protein synthesis. This inhibition results from the blocking of the peptidyltransferase site of the 50S subunit of tile bacterial ribosome. Little effect on DNA and RNA synthesis was observed. 

The findings that demonstrated the activity of compound 4 (Fig. 9) under anaerobic conditions opened the studies of QDO as specific anti-microorganism agents. Anaerobic antibacterial mechanism of compound 4 involves DNA synthesis inhibition without effects on the RNA and proteins syntheses [114]. It has been demonstrated that compound 6 inhibits Staphylococcus aureus DNase biosynthesis and plasma coagulase [115]. 

For example, in cultures of Bacillus subtilis, protein synthesis had ceased entirely after one fourth of a doubling time when RNA synthesis was specifically and completely inhibited by actionomycin D33. Since the initiation of a new round of DNA biosynthesis requires the ad hoc synthesis of initiator protein(s), DNA biosynthesis comes to a standstill after a lag as the result of the failure of initiator protein synthesis. This interesting sequence of events was first described by Kirk34 for the action of actinomycin D in Staphylococcus aureus. 

Mupirocin is an antibiotic agent that inhibits bacterial protein synthesis. It is indicated in treatment of impetigo caused by Staphylococcus aureus and Streptococcus pyogenes (topical ointment) and treatment of secondarily infected traumatic skin lesions (up to 10 cm in length or 100 cm in area). 

Quinupristin/dalfopristin is a streptogramin. Quinupristin inhibits the late phase of protein synthesis dalfopristin inhibits the early phase of protein synthesis. It is indicated in the treatment of serious or life-threatening infections associated with VREF treatment of complicated skin and skin-structure infections caused by Staphylococcus aureus (methicillin-susceptible) or Streptococcus pyogenes. 

It is widely accepted that MLS antibiotics inhibit protein synthesis by binding to closely related sites on the 508 subunit of the 70S ribosome of bacteria [4], despite being structurally different from each other (see Figs. 1 and 2 in a later section). That is the reason why, when inducible resistant Staphylococcus aureus cells are exposed to a low concentration of the drug (0.05 tg erythromycin/ml - 6.8 x 10 M), they show resistance against not only erythromycin but also other macrolide antibiotics as well as lincosamide and type B streptogramin antibiotics. Erythromycin has been widely used and has been the object of extensive molecular and biological studies. 

Mao, J. C.-H. (1967). Protein synthesis in a cell-free extract from Staphylococcus aureus. J. Bacterial. 94, 80-86. 

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