scholarly journals Ketolide Antimicrobial Activity Persists after Disruption of Interactions with Domain II of 23S rRNA

2004 ◽  
Vol 48 (10) ◽  
pp. 3677-3683 ◽  
Author(s):  
Guy W. Novotny ◽  
Lene Jakobsen ◽  
Niels M. Andersen ◽  
Jacob Poehlsgaard ◽  
Stephen Douthwaite
Keyword(s):  
Antimicrobial Activity ◽  
Ribosomal Subunit ◽  
23S Rrna ◽  
Alkyl Aryl ◽  
Interaction Sites ◽  
Enhanced Resistance ◽  
Low Levels ◽  
Domain V ◽  
Block Protein Synthesis ◽  
Do So

ABSTRACT Ketolides are the latest derivatives developed from the macrolide erythromycin to improve antimicrobial activity. All macrolides and ketolides bind to the 50S ribosomal subunit, where they come into contact with adenosine 2058 (A2058) within domain V of the 23S rRNA and block protein synthesis. An additional interaction at nucleotide A752 in the rRNA domain II is made via the synthetic carbamate-alkyl-aryl substituent in the ketolides HMR3647 (telithromycin) and HMR3004, and this interaction contributes to their improved activities. Only a few macrolides, including tylosin, come into contact with domain II of the rRNA and do so via interactions with nucleotides G748 and A752. We have disrupted these macrolide-ketolide interaction sites in the rRNA to assess their relative importance for binding. Base substitutions at A752 were shown to confer low levels of resistance to telithromycin but not to HMR3004, while deletion of A752 confers low levels of resistance to both ketolides. Mutations at position 748 confer no resistance. Substitution of guanine at A2058 gives rise to the MLSB (macrolide, lincosamide, and streptogramin B) phenotype, which confers resistance to all the drugs. However, resistance to ketolides was abolished when the mutation at position 2058 was combined with a mutation in domain II of the same rRNA. In contrast, the same dual mutations in rRNAs conferred enhanced resistance to tylosin. Our results show that the domain II interactions of telithromycin and HMR3004 differ from each other and from those of tylosin. The data provide no indication that mutations within domain II, either alone or in combination with an A2058 mutation, can confer significant levels of telithromycin resistance.

scholarly journals Oxazolidinone Resistance Mutations in 23S rRNA ofEscherichia coli Reveal the Central Region of Domain V as the Primary Site of Drug Action

2000 ◽  
Vol 182 (19) ◽  
pp. 5325-5331 ◽  
Author(s):  
Liqun Xiong ◽  
Patricia Kloss ◽  
Stephen Douthwaite ◽  
Niels Møller Andersen ◽  
Steven Swaney ◽  
...  
Keyword(s):  
Ribosomal Subunit ◽  
Site Directed Mutagenesis ◽  
Rrna Operon ◽  
Rrna Genes ◽  
23S Rrna ◽  
Peptide Bond Formation ◽  
Resistance Mutations ◽  
Peptidyl Transferase ◽  
Central Loop ◽  
Domain V

ABSTRACT Oxazolidinone antibiotics inhibit bacterial protein synthesis by interacting with the large ribosomal subunit. The structure and exact location of the oxazolidinone binding site remain obscure, as does the manner in which these drugs inhibit translation. To investigate the drug-ribosome interaction, we selected Escherichia colioxazolidinone-resistant mutants, which contained a randomly mutagenized plasmid-borne rRNA operon. The same mutation, G2032 to A, was identified in the 23S rRNA genes of several independent resistant isolates. Engineering of this mutation by site-directed mutagenesis in the wild-type rRNA operon produced an oxazolidinone resistance phenotype, establishing that the G2032A substitution was the determinant of resistance. Engineered U and C substitutions at G2032, as well as a G2447-to-U mutation, also conferred resistance to oxazolidinone. All the characterized resistance mutations were clustered in the vicinity of the central loop of domain V of 23S rRNA, suggesting that this rRNA region plays a major role in the interaction of the drug with the ribosome. Although the central loop of domain V is an essential integral component of the ribosomal peptidyl transferase, oxazolidinones do not inhibit peptide bond formation, and thus these drugs presumably interfere with another activity associated with the peptidyl transferase center.

scholarly journals Distinct Mode of Interaction of a Novel Ketolide Antibiotic That Displays Enhanced Antimicrobial Activity

2009 ◽  
Vol 53 (4) ◽  
pp. 1411-1419 ◽  
Author(s):  
Ekaterini C. Kouvela ◽  
Dimitrios L. Kalpaxis ◽  
Daniel N. Wilson ◽  
George P. Dinos
Keyword(s):  
Antimicrobial Activity ◽  
Attachment Site ◽  
23S Rrna ◽  
Side Chain ◽  
Macrolide Antibiotics ◽  
Distinct Mode ◽  
Alkyl Aryl ◽  
Resistant Strains ◽  
Exit Tunnel ◽  
A Site

ABSTRACT Ketolides represent the latest generation of macrolide antibiotics, displaying improved activities against some erythromycin-resistant strains, while maintaining their activity against erythromycin-susceptible ones. In this study, we present a new ketolide, K-1325, that carries an alkyl-aryl side chain at C-13 of the lactone ring. According to our genetic and biochemical studies, K-1325 binds within the nascent polypeptide exit tunnel, at a site previously described as the primary attachment site of all macrolide antibiotics. Compared with telithromycin, K-1325 displays enhanced antimicrobial activity against wild-type Escherichia coli strains, as well as against strains bearing the U2609C mutation in 23S rRNA. Chemical protection experiments showed that the alkyl-aryl side chain of K-1325 interacts specifically with helix 35 of 23S rRNA, a fact leading to an increased affinity of U2609C mutant ribosomes for the drug and rationalizing the enhanced effectiveness of this new ketolide.

scholarly journals Macrolide-Resistant and Macrolide-Sensitive Mycoplasma pneumoniae Pneumonia in Children Treated Using Early Corticosteroids

2021 ◽  
Vol 10 (6) ◽  
pp. 1309
Author(s):  
Hye Young Han ◽  
Ki Cheol Park ◽  
Eun-Ae Yang ◽  
Kyung-Yil Lee
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Serological Test ◽  
Corticosteroid Treatment ◽  
23S Rrna ◽  
Laboratory Parameters ◽  
The Mean ◽  
Domain V ◽  
Positive Results ◽  
Mycoplasma Pneumoniae Pneumonia

We have found that early corticosteroid therapy was effective for reducing morbidity during five Korea-wide epidemics. We evaluated the clinical and laboratory parameters of 56 children who received early corticosteroid treatment for pneumonia that was caused by macrolide-resistant Mycoplasma pneumoniae (M. pneumoniae) or macrolide-sensitive M. pneumoniae between July 2019 and February 2020. All subjects had dual positive results from a PCR assay and serological test, and received corticosteroids within 24–36 h after admission. Point mutation of residues 2063, 2064, and 2067 was identified in domain V of 23S rRNA. The mean age was 6.8 years and the male:female ratio was 1.2:1 (31:25 patients). Most of the subjects had macrolide-resistant M. pneumoniae (73%), and all mutated strains had the A2063G transition. No significant differences in clinical and laboratory parameters were observed between macrolide-resistant and macrolide-sensitive M. pneumoniae groups that were treated with early dose-adjusted corticosteroids. Higher-dose steroid treatment may be needed for patients who have fever that persists for >48 h or increased biomarkers such as lactate dehydrogenase concentration at follow-up despite a usual dose of steroid therapy.

scholarly journals Binding Site of the Bridged Macrolides in the Escherichia coli Ribosome

2005 ◽  
Vol 49 (1) ◽  
pp. 281-288 ◽  
Author(s):  
Liqun Xiong ◽  
Yakov Korkhin ◽  
Alexander S. Mankin
Keyword(s):  
Escherichia Coli ◽  
Tight Binding ◽  
Dimethyl Sulfate ◽  
23S Rrna ◽  
Side Chain ◽  
Macrolide Antibiotics ◽  
Side Chains ◽  
Alkyl Aryl ◽  
E Coli ◽  
Exit Tunnel

ABSTRACT Ketolides represent the latest group of macrolide antibiotics. Tight binding of ketolides to the ribosome appears to correlate with the presence of an extended alkyl-aryl side chain. Recently developed 6,11-bridged bicyclic ketolides extend the spectrum of platforms used to generate new potent macrolides with extended alkyl-aryl side chains. The purpose of the present study was to characterize the site of binding and the action of bridged macrolides in the ribosomes of Escherichia coli. All the bridged macrolides investigated efficiently protected A2058 and A2059 in domain V of 23S rRNA from modification by dimethyl sulfate and U2609 from modification by carbodiimide. In addition, bridged macrolides that carry extended alkyl-aryl side chains protruding from the 6,11 bridge protected A752 in helix 35 of domain II of 23S rRNA from modification by dimethyl sulfate. Bridged macrolides efficiently displaced erythromycin from the ribosome in a competition binding assay. The A2058G mutation in 23S rRNA conferred resistance to the bridged macrolides. The U2609C mutation, which renders E. coli resistant to the previously studied ketolides telithromycin and cethromycin, barely affected cell susceptibility to the bridged macrolides used in this study. The results of the biochemical and genetic studies indicate that in the E. coli ribosome, bridged macrolides bind in the nascent peptide exit tunnel at the site previously described for other macrolide antibiotics. The presence of the side chain promotes the formation of specific interactions with the helix 35 of 23S rRNA.

scholarly journals Synthesis of Trypsin-Resistant Variants of the Listeria-Active Bacteriocin Salivaricin P

2010 ◽  
Vol 76 (16) ◽  
pp. 5356-5362 ◽  
Author(s):  
Eileen F. O'Shea ◽  
Paula M. O'Connor ◽  
Paul D. Cotter ◽  
R. Paul Ross ◽  
Colin Hill
Keyword(s):  
Antimicrobial Activity ◽  
Gastrointestinal Tract ◽  
Cleavage Sites ◽  
Wild Type ◽  
Enhanced Resistance ◽  
Fold Reduction ◽  
Two Component ◽  
Specific Protease ◽  
The Individual ◽  
Protease Action

ABSTRACT Two-component salivaricin P-like bacteriocins have demonstrated potential as antimicrobials capable of controlling infections in the gastrointestinal tract (GIT). The anti-Listeria activity of salivaricin P is optimal when the individual peptides Sln1 and Sln2 are added in succession at a 1:1 ratio. However, as degradation by digestive proteases may compromise the functionality of these peptides within the GIT, we investigated the potential to create salivaricin variants with enhanced resistance to the intestinal protease trypsin. A total of 11 variants of the salivaricin P components, in which conservative modifications at the trypsin-specific cleavage sites were explored in order to protect the peptides from trypsin degradation while maintaining their potent antimicrobial activity, were generated. Analysis of these variants revealed that eight were resistant to trypsin digestion while retaining antimicrobial activity. Combining the complementary trypsin-resistant variants Sln1-5 and Sln2-3 resulted in a MIC50 of 300 nM against Listeria monocytogenes, a 3.75-fold reduction in activity compared to the level for wild-type salivaricin P. This study demonstrates the potential of engineering bacteriocin variants which are resistant to specific protease action but which retain significant antimicrobial activity.

scholarly journals Halobacterium cutirubrum ribosomes. Properties of the ribosomal proteins and ribonucleic acid

1972 ◽  
Vol 130 (1) ◽  
pp. 103-110 ◽  
Author(s):  
L. P. Visentin ◽  
C. Chow ◽  
A. T. Matheson ◽  
M. Yaguchi ◽  
F. Rollin
Keyword(s):  
Ribosomal Protein ◽  
Ribosomal Proteins ◽  
Soluble Fraction ◽  
Ribosomal Subunit ◽  
23S Rrna ◽  
Core Particle ◽  
Fractionation Procedure ◽  
Additional Protein ◽  
70S Ribosome ◽  
Low Ionic Strength

1. The 30S ribosomal subunit of the extreme halophile Halobacterium cutirubrum is unstable and loses 75% of its ribosomal protein when the 70S ribosome is dissociated into the two subunits. A stable 30S subunit is obtained if the dissociation of the 70S particle is carried out in the presence of the soluble fraction. 2. A fractionation procedure was developed for the selective removal of groups of proteins from the 30S and 50S subunits. When the ribosomes, which are stable in 4m-K+ and 0.1m-Mg2+, were extracted with low-ionic-strength buffer 75–80% of the 30S proteins and 60–65% of the 50S proteins as well as the 5S rRNA were released. The proteins in this fraction are the most acidic of the H. cutirubrum ribosomal proteins. Further extraction with Li+–EDTA releases additional protein, leaving a core particle containing either 16S rRNA or 23S rRNA and about 5% of the total ribosomal protein. The amino acid composition, mobility on polyacrylamide gels at pH4.5 and 8.7, and the molecular-weight distribution of the various protein fractions were determined. 3. The s values of the rRNA are 5S, 16S and 23S. The C+G contents of the 16S and 23S rRNA were 56.1 and 58.8% respectively and these are higher than C+G contents of the corresponding Escherichia coli rRNA (53.8 and 54.1%).

scholarly journals Protein Folding by Domain V of Escherichia coli 23S rRNA: Specificity of RNA-Protein Interactions

2008 ◽  
Vol 190 (9) ◽  
pp. 3344-3352 ◽  
Author(s):  
Dibyendu Samanta ◽  
Debashis Mukhopadhyay ◽  
Saheli Chowdhury ◽  
Jaydip Ghosh ◽  
Saumen Pal ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Folding ◽  
Carbonic Anhydrase ◽  
Protein Interactions ◽  
23S Rrna ◽  
Unfolded Proteins ◽  
Bovine Carbonic Anhydrase ◽  
Egg White Lysozyme ◽  
General Protein ◽  
Domain V

ABSTRACT The peptidyl transferase center, present in domain V of 23S rRNA of eubacteria and large rRNA of plants and animals, can act as a general protein folding modulator. Here we show that a few specific nucleotides in Escherichia coli domain V RNA bind to unfolded proteins and, as shown previously, bring the trapped proteins to a folding-competent state before releasing them. These nucleotides are the same for the proteins studied so far: bovine carbonic anhydrase, lactate dehydrogenase, malate dehydrogenase, and chicken egg white lysozyme. The amino acids that interact with these nucleotides are also found to be specific in the two cases tested: bovine carbonic anhydrase and lysozyme. They are either neutral or positively charged and are present in random coils on the surface of the crystal structure of both the proteins. In fact, two of these amino acid-nucleotide pairs are identical in the two cases. How these features might help the process of protein folding is discussed.

scholarly journals Green ultrasound-assisted three-component click synthesis of novel 1H-1,2,3-triazole carrying benzothiazoles and fluorinated-1,2,4-triazole conjugates and their antimicrobial evaluation

2017 ◽  
Vol 67 (3) ◽  
pp. 309-324 ◽  
Author(s):  
Nadjet Rezki ◽  
Mohamed Reda Aouad
Keyword(s):  
Antimicrobial Activity ◽  
Cycloaddition Reaction ◽  
Dipolar Cycloaddition ◽  
Terminal Alkynes ◽  
One Pot ◽  
Alkyl Aryl ◽  
Antimicrobial Evaluation ◽  
Ultrasound Assisted ◽  
Click Synthesis

AbstractThe present study describes an efficient and ecofriendly, ultrasound, one-pot click cycloaddition approach for the construction of a novel series of 1,4-disubstituted-1,2,3-triazoles tethered with fluorinated 1,2,4-triazole-benzothiazole molecular conjugates. It involved three-component condensation of the appropriate bromoacetamide benzothiazole, sodium azide and 4-alkyl/aryl-5-(2-fluorophenyl)-3-(prop-2-ynylthio)-1,2,4-triazoles4a-ethrough a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction. This approach involvesin situgeneration of azidoacetamide benzothiazole, followed by condensation with terminal alkynes in the presence of CuSO4/Na-ascorbate in aqueous DMSO under both conventional and ultrasound conditions. Some of the designed 1,2,3-triazole conjugates6a-owere recognized for their antimicrobial activity against some bacterial and fungal pathogenic strains.

scholarly journals Mutations in domain V of Mycoplasma pneumoniae 23S rRNA are not associated with clinical characteristics of M. pneumoniae pneumonia in children: a case control study

2020 ◽  
Author(s):  
Huan Deng ◽  
Yifan Zhu ◽  
Jiamin Zhang ◽  
Qiangquan Rong ◽  
Yao Quan ◽  
...  
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Lymphocyte Count ◽  
Clinical Characteristics ◽  
Clinical Symptoms ◽  
Laboratory Data ◽  
Point Mutations ◽  
Community Acquired Pneumonia ◽  
Pulmonary Complications ◽  
23S Rrna ◽  
Domain V

Abstract Background Mycoplasma pneumoniae (MP) is a common agent of community-acquired pneumonia in children and young adults that can lead to refractory or persistent Mycoplasma pneumoniae pneumonia (MPP). Macrolide-resistant MP harbors point mutations in domain V of 23S ribosomal Ribonucleic Acid (rRNA) with substitutions detected at positions 2063, 2064, 2067 and 2617. This study’s purpose is to investigate the prevalence and clinical characteristics of mutations in domain V of MP 23S rRNA. Methods We sequenced the 23S rRNA domain V of MP strains collected from children with MPP. Clinical and laboratory data were also obtained, including gender, age, duration of fever, duration of fever after the start of macrolide therapy, MP-Deoxyribonucleic Acid (DNA) load at enrollment, leukocyte count, neutrophil count, and lymphocyte count, immunomodulators treatment and pulmonary complications.Results Of 276 strains, 255 (92.39 %) harbored A to G transition at the position 2063 (A2063G), and 21 (7.61 %) were not mutated. There were no significant differences in gender, age, duration of fever, duration of fever after the start of macrolide therapy, MP-DNA load at enrollment, hospitalization days, lymphocyte count and pulmonary complications when patients were stratified based on the presence or absence of domain V mutations. We also found that children with refractory MPP experienced higher MP-DNA load than the non-refractory MPP, but the prevalence of domain V mutations was comparable.Conclusions We found that clinical MP strains harbored very high mutation rate in 23S rRNA domain V, especially A2063G mutation. However, these mutations were not associated with clinical symptoms, laboratory results, pulmonary complications and development of refractory pneumonia. Instead, MP-DNA load was significantly different between refractory and non-refractory MPP.

scholarly journals Drug Resistance Mechanisms ofMycoplasma pneumoniaeto Macrolide Antibiotics

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Xijie Liu ◽  
Yue Jiang ◽  
Xiaogeng Chen ◽  
Jing Li ◽  
Dawei Shi ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Resistance Mechanisms ◽  
23S Rrna ◽  
Macrolide Antibiotics ◽  
Rrna Gene ◽  
Site Mutation ◽  
23S Rrna Gene ◽  
Resistant Strains ◽  
Domain V ◽  
The 16S Rrna Gene

Throat swabs from children with suspectedMycoplasma pneumoniae(M. pneumoniae) infection were cultured for the presence ofM. pneumoniaeand its species specificity using the 16S rRNA gene. Seventy-sixM. pneumoniaestrains isolated from 580 swabs showed that 70 were erythromycin resistant with minimum inhibitory concentrations (MIC) around 32–512 mg/L. FiftyM. pneumoniaestrains (46 resistant, 4 sensitive) were tested for sensitivity to tetracycline, ciprofloxacin, and gentamicin. Tetracycline and ciprofloxacin had some effect, and gentamicin had an effect on the majority ofM. pneumoniaestrains. Domains II and V of the 23S rRNA gene and the ribosomal protein L4 and L22 genes, both of which are considered to be associated with macrolide resistance, were sequenced and the sequences were compared with the corresponding sequences in M129 registered with NCBI and the FH strain. The 70 resistant strains all showed a 2063 or 2064 site mutation in domain V of the 23S rRNA but no mutations in domain II. Site mutations of L4 or L22 can be observed in either resistant or sensitive strains, although it is not known whether this is associated with drug resistance.

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