We thus examined azithromycin accretion in adipose tissues of obese patients that correlates with BMI by high performance liquid chromatography-tandem mass spectrometry and systematically explore the influences of azithromycin on adiposity and metabolic performance in mice under high diet. Methods: We screened major types of antibiotics to examine their effects on the differentiation capacity and thermogenic functionality of brown and beige adipocytes, and found that azithromycin, one major kind of macrolide antibiotics suppressed brown and beige adipocyte functionality. However, the effects of antibiotics exposure on fat metabolism and metabolic diseases are largely unknown. Antibiotics, a new type of environmental pollutant, have been widely used in animal husbandry, aquaculture and microorganism. In addition to nutrient intake and sedentary lifestyle, environmental pollutants exposure has been shown to be involved in obesity epidemics. Obesity, a metabolic disease caused by multiple factors, has become a global health problem. The authors determine the cryo-EM structures of prokaryotic ribosomes with the oxazolidinone antibiotics linezolid and radezolid bound to the peptidyl transferase center with an adjacent growing nascent peptide chain, providing an explanation for their context-specific action. Together, our findings provide molecular understanding for the context-specificity of oxazolidinones. Modification of the ribosome by the antibiotic resistance enzyme Cfr disrupts stalling due to repositioning of the modified nucleotide. These structures reveal that the alanine side chain fits within a small hydrophobic crevice created by oxazolidinone, resulting in improved ribosome binding. Here we show that the second-generation oxazolidinone radezolid also induces stalling with a penultimate alanine, and we determine high-resolution cryo-EM structures of linezolid- and radezolid-stalled ribosome complexes to explain their mechanism of action. However, the molecular basis for context-specificity has not been elucidated. Recent work has demonstrated that linezolid does not inhibit peptide bond formation at all sequences but rather acts in a context-specific manner, namely when alanine occupies the penultimate position of the nascent chain. The antibiotic linezolid, the first clinically approved member of the oxazolidinone class, inhibits translation of bacterial ribosomes by binding to the peptidyl transferase center. (C) The listed nucleoside analogs were introduced via the atomic mutagenesis approach into the PTC or the exit tunnel of the 50S ribosomal subunit and their activities were tested in macrolide-dependent ribosome stalling. Amino acids for which sufficient density was observed in the SRC are labeled in grey.
The sugar-phosphate backbone of the P-site located peptidyl-tRNA and the density for I 6 F 7 V 8 I 9 of ErmCL are depicted in dark and light grey, respectively.
The PTC residue A2451, whose ribose 2-OH group is pivotal for peptide bond formation (23,40), is shown as well to indicate the catalytic heart of the active site. (B) 3D representation of the PTC and tunnel residues in the ErmCL stalled ribosomal complex (18) (based on the structure pdb 3J7Z) that have been modified and tested for their impact on ribosomal stalling. Shine Dalgarno sequence, start and stop codons are shown in red. Amino acid sequence of ErmC leader peptide (ErmCL) and the N-terminus of the ErmC are depicted above the corresponding codons. The exit tunnel-bound macrolide antibiotic in the large 50S subunit is depicted as purple hexagon and the nascent peptide chain is in green. (A) Structure of the regulatory region of the inducible ermC gene in the non-induced (upper panel) and induced (lower panel) conformation. The macrolide-inducible ermC gene and the 23S rRNA residues investigated for their role in translation arrest.