Figure 2

Overview of the mode of action of antibiotics used to treat S. suis infections. According to its target site, antibiotics can be classified as A inhibitors of peptidoglycan (PG) synthesis by blocking penicillin-binding proteins (PBPs) (β-lactams) or binding D-Ala-D-Ala in the peptide chain of the PG precursor lipid II (glycopeptides), B inhibitors of ribosome function that bind to the ribosome 50S (macrolides, amphenicols, lincosamides, and pleuromutilins) or 30S (tetracyclines and aminoglycosides) subunits, C inhibitors of folic acid synthesis including sulfonamides and trimethoprim, and D inhibitors of DNA transcription and replication by interfering with DNA gyrase or topoisomerase IV (quinolones). In A, the process of the synthesis and transport of PG precursors is indicated. The 30S and 50S ribosome subunits and the A, P, and E sites are indicated in B. The A site is the binding site for charged tRNA molecules during protein synthesis. Then, the tRNA moves to the P site and its cargo is then linked to the growing polypeptide chain. Thereafter, the tRNA is moved to the E site for exit. The route for folate synthesis is shown in C. In D, the requirement for DNA gyrase and topoisomerase IV in DNA transcription and replication processes is shown. Antibiotics are indicated with colored stars. A red circle indicates resulting inhibition of the cellular process. Abbreviations: PABA, p-aminobenzoic acid; pteridine, 7,8-dihydro-6-hydroxymethylpterin-pyrophosphate; UDP, uridine diphosphate.