Journal Article

Structural basis of broad-spectrum β-lactam resistance in Staphylococcus aureus

Alexander, J. Andrew N., Chambers, Henry F., Rosell, Federico I., Hu, Jinhong, Poon, Raymond, Worrall, Liam J., Strynadka, Natalie C. J., Paetzel, Mark, Jenkins, Joshua, Chiang, Daniel, Vuckovic, Marija, Chatterjee, Som S., Mosimann, Wesley A., Sobhanifar, Solmaz, Satishkumar, Nidhi

2023

Overview

Broad-spectrum β-lactam antibiotic resistance in Staphylococcus aureus is a global healthcare burden 1 , 2 . In clinical strains, resistance is largely controlled by BlaR1 3 , a receptor that senses β-lactams through the acylation of its sensor domain, inducing transmembrane signalling and activation of the cytoplasmic-facing metalloprotease domain 4 . The metalloprotease domain has a role in BlaI derepression, inducing blaZ (β-lactamase PC1) and mecA (β-lactam-resistant cell-wall transpeptidase PBP2a) expression 3 – 7 . Here, overcoming hurdles in isolation, we show that BlaR1 cleaves BlaI directly, as necessary for inactivation, with no requirement for additional components as suggested previously 8 . Cryo-electron microscopy structures of BlaR1—the wild type and an autocleavage-deficient F284A mutant, with or without β-lactam—reveal a domain-swapped dimer that we suggest is critical to the stabilization of the signalling loops within. BlaR1 undergoes spontaneous autocleavage in cis between Ser283 and Phe284 and we describe the catalytic mechanism and specificity underlying the self and BlaI cleavage. The structures suggest that allosteric signalling emanates from β-lactam-induced exclusion of the prominent extracellular loop bound competitively in the sensor-domain active site, driving subsequent dynamic motions, including a shift in the sensor towards the membrane and accompanying changes in the zinc metalloprotease domain. We propose that this enhances the expulsion of autocleaved products from the active site, shifting the equilibrium to a state that is permissive of efficient BlaI cleavage. Collectively, this study provides a structure of a two-component signalling receptor that mediates action—in this case, antibiotic resistance—through the direct cleavage of a repressor. Cryo-electron microscopy structures of Staphylococcus aureus BlaR1 reveal dynamic signalling states regulating broad spectrum β-lactam antibiotic resistance through cleavage of the transcriptional repressor BlaI and induced expression of the β-lactamase blaZ and the β-lactam-resistant cell-wall transpeptidase mecA .

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 101/28 / 631/326/22/1434 / 631/45/173 / 631/45/474 / 631/535/1258/1259 / Acylation / Allosteric properties / Amides / Anti-Bacterial Agents - chemistry / Anti-Bacterial Agents - pharmacology / Antibiotic resistance / Antibiotics / Bacterial infections / Bacterial Proteins - chemistry / Bacterial Proteins - metabolism / beta-Lactam Resistance - drug effects / beta-Lactams - chemistry / beta-Lactams - pharmacology / Cleavage / Cryoelectron Microscopy / Derepression / Domains / Drug resistance / Electron microscopy / Expulsion / Gene expression / Global health / Humanities and Social Sciences / Humans / Inactivation / Metalloproteinase / Microscopy / multidisciplinary / Penicillin / Receptors / Science / Science & Technology - Other Topics / Science (multidisciplinary) / Sensors / Signal transduction / Signaling / Staphylococcal Infections - microbiology / Staphylococcus aureus / Staphylococcus aureus - drug effects / Staphylococcus aureus - enzymology / Staphylococcus aureus - metabolism / Staphylococcus infections / β Lactamase / β-Lactam antibiotics