Specific Inhibition of 50S Ribosomal Subunit Formation in Staphylococcus aureus Cells by 16-Membered Macrolide, Lincosamide, and Streptogramin B Antibiotics

Antimicrobial coatings can reduce the occurrence of medical device-related bacterial infections. Poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is one such polymer that is being researched in this regard. The aims of this study were to (1) elucidate pDMAEMA’s antimicrobial activity against a range of Gram-positive and Gram-negative bacteria and (2) to investigate its antimicrobial mode of action. The methods used include determination of minimum inhibitory concentration (MIC) values against various bacteria and the effect of pH and temperature on antimicrobial activity. The ability of pDMAEMA to permeabilise bacterial membranes was determined using the dyes 1-N-phenyl-naphthylamine and calcein-AM. Flow cytometry was used to investigate pDMAEMA’s capacity to be internalized by bacteria and to determine effects on bacterial cell cycling. pDMAEMA was bacteriostatic against Gram-negative bacteria with MIC values between 0.1−1 mg/mL. MIC values against Gram-positive bacteria were variable. pDMAEMA was active against Gram-positive bacteria around its pK a and at lower pH values, while it was active against Gram-negative bacteria around its pK a and at higher pH values. pDMAEMA inhibited bacterial growth by binding to the outside of the bacteria, permeabilizing the outer membrane and disrupting the cytoplasmic membrane. By incorporating pDMAEMA with erythromycin, it was found that the efficacy of the latter was increased against Gram-negative bacteria. Together, the results illustrate that pDMAEMA acts in a similar fashion to other cationic biocides.

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“…Erythromycin is a hydrophobic, macrolide, antibiotic that is extensively used in treating Gram-positive bacterial infections 62,63 .…”

Section: Discussionmentioning

confidence: 99%

Antibacterial Effects of Poly(2-(dimethylamino ethyl)methacrylate) against Selected Gram-Positive and Gram-Negative Bacteria

et al. 2009

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“…Erythromycin does not inhibit the peptidyltransferase activity but prevents the extension of the peptide chain by blocking the polypeptide exit tunnel and provokes the premature release of peptidyl-tRNA (24). Moreover, erythromycin also prevents ribosomal assembly at an early stage of protein synthesis (6).…”

Section: Ribosome Binding Site and Mode Of Action Of Erythromycinmentioning

confidence: 99%

Resistance to Macrolides and Related Antibiotics in Streptococcus pneumoniae

Leclercq

Courvalin

2002

Antimicrob Agents Chemother

242

167

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2Resistance to erythromycin in Streptococcus pneumoniae was first detected in 1967 in the United States and subsequently worldwide (11,20). The corresponding mechanism was rapidly identified as ribosomal methylation, which had been primarily reported as being responsible for erythromycin resistance in staphylococci (44). Further spread of resistance was then noted in a few countries, such as France, where hospitals observed a sharp increase in the proportion of resistant pneumococci, which reached approximately 20% in 1984 (16). This trend was observed several years before the emergence and spread of penicillin resistance in pneumococci in France. Recently, an increasing number of countries have noted changes in the evolution of macrolide resistance. In some of them, such as the United States, increased incidence has been correlated with the emergence of a new mechanism of erythromycin resistance-efflux (39). This review is devoted to the mechanisms responsible for resistance to macrolides and related antibiotics in pneumococci. THE MACROLIDESMacrolides have a common structure formed by a large lactone ring. Erythromycin is a mixture of antibiotics that includes erythromycin A, which is the active compound and which has a 14-membered lactone ring with two sugars, Lcladinose and an amino sugar. Other commercially available macrolides derived from erythromycin A include clarithromycin, dirithromycin, roxithromycin, and azithromycin, which has an enlarged, 15-membered ring resulting from a nitrogen insertion. The structural modifications of erythromycin A resulted in improved pharmacokinetic profiles and better tolerance, but cross-resistance between members of this class of antimicrobial agents was still observed. Certain 16-membered macrolides are also available in a few countries (spiramycin, josamycin, midecamycin, and miocamycin) or for veterinary use (tylosin). The recently developed ketolides telithromycin and ABT773 are derived from clarithromycin and have two major modifications, replacement of L-cladinose by a keto function and an 11-to 12-carbamate extension with an arylalkyl modification in telithromycin, the latter of which may partially explain its increased intrinsic activity and activity against erythromycin-resistant strains, as discussed below (13,33). In telithromycin and ABT773, modification at the C-6 position prevents inactivation of the molecule in acid medium. RIBOSOME BINDING SITE AND MODE OF ACTION OF ERYTHROMYCINThe ribosome structure and contact points between the ribosome and erythromycin A were recently identified by crystallography studies (35). The bacterial ribosome is formed by a small, 30S subunit and a large, 50S subunit. The latter is composed of 23S rRNA and of a minimum of 30 proteins. The secondary structure of 23S rRNA is folded due to base pairing and forms six domains numbered I to VI, while the tertiary structure of the molecule is maintained by its interactions with proteins. Stoichiometric binding of erythromycin A to the 50S subunit causes inhibition of protein synthes...

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“…The drugs proposed to have such an effect included macrolides and ketolides (10,11,15,35,59), streptogramin B (16), lincosamides (16), aminoglycosides (36), evernimicin (14), linezolid (12), and pleuromutilins (13). However, the indirect mechanism of assembly inhibition cannot be excluded for any of these drugs.…”

mentioning

confidence: 99%

Erythromycin- and Chloramphenicol-Induced Ribosomal Assembly Defects Are Secondary Effects of Protein Synthesis Inhibition

Siibak

Peil

Xiong

et al. 2009

Antimicrob Agents Chemother

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Several protein synthesis inhibitors are known to inhibit ribosome assembly. This may be a consequence of direct binding of the antibiotic to ribosome precursor particles, or it could result indirectly from loss of coordination in the production of ribosomal components due to the inhibition of protein synthesis. Here we demonstrate that erythromycin and chloramphenicol, inhibitors of the large ribosomal subunit, affect the assembly of both the large and small subunits. Expression of a small erythromycin resistance peptide acting in cis on mature ribosomes relieves the erythromycin-mediated assembly defect for both subunits. Erythromycin treatment of bacteria expressing a mixture of erythromycin-sensitive and -resistant ribosomes produced comparable effects on subunit assembly. These results argue in favor of the view that erythromycin and chloramphenicol affect the assembly of the large ribosomal subunit indirectly.The ribosome is a target for many medically important antibiotics (42,56,63). These drugs bind to either the small or the large subunit and inhibit essential ribosome functions: decoding, peptidyl transfer, transit of the nascent peptide chain, or activation of ribosome-associated GTPases. In addition, antibiotics cause many physiological changes; for example, they induce stress response pathways and alter gene expression patterns in other ways (23,25,45,60).One of the known "side effects" of ribosome-targeting antibiotics is inhibition of ribosome assembly. This effect was originally described for chloramphenicol: defective particles sedimenting more slowly than mature ribosomal subunits were observed in cells treated with this drug (19,29). Such particles contain precursor forms of rRNA and an incomplete set of ribosomal proteins (1, 53). During chloramphenicol treatment, ribosomal proteins are produced in nonstoichiometric amounts (20). In addition, the equilibrium between the production of rRNA and ribosomal proteins is upset, and rRNA is expressed in excess (30,37,49). It has been proposed that this unbalanced synthesis of components is responsible for the chloramphenicol-induced defects in ribosomal assembly (21).More recently, Champney and colleagues suggested that several other inhibitors of protein synthesis stall the assembly of ribosomal subunits by binding to the respective precursor particles. The drugs proposed to have such an effect included macrolides and ketolides (10,11,15,35,59), streptogramin B (16), lincosamides (16), aminoglycosides (36), evernimicin (14), linezolid (12), and pleuromutilins (13). However, the indirect mechanism of assembly inhibition cannot be excluded for any of these drugs.To investigate the mechanism by which ribosome assembly is inhibited, we chose two inhibitors of the 50S subunit, erythromycin and chloramphenicol, and carried out experiments designed to differentiate between the two alternative hypotheses: (i) direct inhibition due to the binding of antibiotics to the precursor particles and (ii) indirect inhibition, when an imbalance in the production of c...

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Specific Inhibition of 50S Ribosomal Subunit Formation in Staphylococcus aureus Cells by 16-Membered Macrolide, Lincosamide, and Streptogramin B Antibiotics

Cited by 55 publications

References 46 publications

Antibacterial Effects of Poly(2-(dimethylamino ethyl)methacrylate) against Selected Gram-Positive and Gram-Negative Bacteria

Antibacterial Effects of Poly(2-(dimethylamino ethyl)methacrylate) against Selected Gram-Positive and Gram-Negative Bacteria

Resistance to Macrolides and Related Antibiotics in Streptococcus pneumoniae

Erythromycin- and Chloramphenicol-Induced Ribosomal Assembly Defects Are Secondary Effects of Protein Synthesis Inhibition

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