Binding of oxytetracycline to E coli ribosomes

Ethylicin Prevents Potato Late Blight by Disrupting Protein Biosynthesis of Phytophthora infestans

Phytophthora infestans, the causal agent of potato late blight, triggered the devastating Great Irish Famine that lasted from 1845 to 1852. Today, it is still the greatest threat to the potato yield. Ethylicin is a broad-spectrum biomimetic-fungicide. However, its application in the control of Phytophthora infestans is still unknown. In this study, we investigated the effects of ethylicin on Phytophthora infestans. We found that ethylicin inhibited the mycelial growth, sporulation capacity, spore germination and virulence of Phytophthora infestans. Furthermore, the integrated analysis of proteomics and metabolomics indicates that ethylicin may inhibit peptide or protein biosynthesis by suppressing both the ribosomal function and amino acid metabolism, causing an inhibitory effect on Phytophthora infestans. These observations indicate that ethylicin may be an anti-oomycete agent that can be used to control Phytophthora infestans.

Natural products in crop protection

The tremendous increase in crop yields associated with the 'green' revolution has been possible in part by the discovery and utilization of chemicals for pest control. However, concerns over the potential impact of pesticides on human health and the environment has led to the introduction of new pesticide registration procedures, such as the Food Quality Protection Act in the United States. These new regulations have reduced the number of synthetic pesticides available in agriculture. Therefore, the current paradigm of relying almost exclusively on chemicals for pest control may need to be reconsidered. New pesticides, including natural product-based pesticides are being discovered and developed to replace the compounds lost due to the new registration requirements. This review covers the historical use of natural products in agricultural practices, the impact of natural products on the development of new pesticides, and the future prospects for natural products-based pest management.

Interaction of tetracycline with RNA: photoincorporation into ribosomal RNA of Escherichia coli

Photolysis of [3H]tetracycline in the presence of Escherichia coli ribosomes results in an approximately 1:1 ratio of labelling ribosomal proteins and RNAs. In this work we characterize crosslinks to both 16S and 23S RNAs. Previously, the main target of photoincorporation of [3H]tetracycline into ribosomal proteins was shown to be S7, which is also part of the one strong binding site of tetracycline on the 30S subunit. The crosslinks on 23S RNA map exclusively to the central loop of domain V (G2505, G2576 and G2608) which is part of the peptidyl transferase region. However, experiments performed with chimeric ribosomal subunits demonstrate that peptidyltransferase activity is not affected by tetracycline crosslinked solely to the 50S subunits. Three different positions are labelled on the 16S RNA, G693, G1300 and G1338. The positions of these crosslinked nucleotides correlate well with footprints on the 16S RNA produced either by tRNA or the protein S7. This suggests that the nucleotides are labelled by tetracycline bound to the strong binding site on the 30S subunit. In addition, our results demonstrate that the well known inhibition of tRNA binding to the A-site is solely due to tetracycline crosslinked to 30S subunits and furthermore suggest that interactions of the antibiotic with 16S RNA might be involved in its mode of action.