Structural basis for TetM-mediated tetracycline resistance

Abstract

Ribosome protection proteins (RPPs) confer tetracycline resistance by binding to the ribosome and chasing the drug from its binding site. The current model for the mechanism of action of RPPs proposes that drug release is indirect and achieved via conformational changes within the drug-binding site induced upon binding of the RPP to the ribosome. Here we report a cryo-EM structure of the RPP TetM in complex with the 70S ribosome at 7.2-Å resolution. The structure reveals the contacts of TetM with the ribosome, including interaction between the conserved and functionally critical C-terminal extension of TetM and the decoding center of the small subunit. Moreover, we observe direct interaction between domain IV of TetM and the tetracycline binding site and identify residues critical for conferring tetracycline resistance. A model is presented whereby TetM directly dislodges tetracycline to confer resistance.antibiotic | protein synthesis | RNA | tigecycline | translation

Targeting Antibiotic Resistance

“…The superimposition was generated by means of the cryo‐electron microscopy density map EMD‐2183 of the TetM‐70S complex from E. coli according to Jenner et al. and Dönhöfer et al 96, 99…”

“…They are also found in both Gram‐positive and Gram‐negative bacteria, but they are usually more common in Gram‐positive organisms, and tet (M) and tet (O) are the two most common genotypes. Mechanistically, these proteins cause allosteric disruption of the primary tetracycline binding site, which leads to the release of bound tetracycline molecules 99. The ribosome is then able to return to its productive conformation and resume protein synthesis.…”

A Bright Future for Antibiotics?

“…Prominent processes acquiring resistance include modifications of the antibiotic binding pockets by mutations (e.g., macrolide resistance by modification of a component crucial for their binding, A2058G). Other frequently used mechanisms include activation of key enzymatic processes (e.g., methylation of the binding components of macrolide and aminoglycosides by methylases); enzymatic inactivation of the drug, such as the macrolide molecule by esterases (61); removal of the antibiotic drug from its target (i.e., resistance to tetracycline by disturbing the ribosomal protection proteins) (62)(63)(64)(65); and modification of ribosomal proteins essential for ribosomal functionality at the PTC and tunnel entrance, such as rpL3, which is associated with resistance to linezolid, tiamulin, and anisomycin (66,67), or disruption of the interactions between proteins that play key roles in protein biosynthesis (68).…”

Implicancias Estructurales y Fisiológicas de la Célula Bacteriana en los Mecanismos de Resistencia Antibiótica

“…Diversas clases de antibióticos actúan inhibiendo la síntesis de proteínas, sin embargo, las bacterias han desarrollado mecanismos de evasión de la acción de los antibióticos por medio de proteínas de protección ribosomal (RPPs, Ribosomal Protection Protein), (Dönhöfer et al, 2012;Zhou et al;Sharkey et al, 2016). En los sistemas de protección ribosomal, los del tipo ABC-F que incluyen a lsa(A), msr(A), optr(A) y vga(A) protegen a los ribosomas desplazando a los antibióticos por sistemas conjuntos con bombas de expulsión (Sharkey et al, 2016).…”

“…Las proteínas codificadas por estos genes interactúan con proteínas ubicadas dentro del ribosoma, causando un cambio conformacional del sitio primario de unión de las tetraciclinas, promoviendo su liberación desde el ribosoma. (Roberts, 2005, Mosquito et al;Dönhöfer et al;Starosta et al, 2014). La resistencia a ácido fusídico por medio de mutaciones FUS-B impide la inhibición de la sín-tesis proteica, liberando estructuras secundarias mRNA secuestradas por efecto del fármaco.…”