Biology subjects

Gonzalez Lopez, A.

Publications and source records attributed to Gonzalez Lopez, A..

3 recordsLinked to original sources

bioRxiv2026

Structural characterization of ribosome recycling and fusidic acid inhibition in Staphylococcus aureus

During bacterial ribosome recycling, 70S ribosomes are split into subunits by ribosome recycling factor (RRF) and elongation factor G (EF-G). The antibiotic fusidic acid (FA) inhibits elongation and ribosome recycling by locking EF-G to the ribosome. Yet, no functional ribosome recycling FA complex has been successfully captured. Here we used single-particle cryo-electron microscopy to resolve multiple FA-stalled intermediates of Staphylococcus aureus ribosomes, including a previously unobserved complex containing both RRF and EF-G. Our structures reveal how RRF and EF-G jointly disrupt inter-subunit bridges, promote back-rotation of the small subunit, and destabilize the tRNA to facilitate ribosome splitting. We further show that FA predominantly inhibits recycling by trapping EF-G on the post-termination complex in the absence of RRF, preventing formation of the active RRF*EF-G complex. These insights advance understanding of the molecular mechanism of bacterial ribosome recycling and the mode of action of FA as an antibiotic. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=79 SRC="FIGDIR/small/721003v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@12951c2org.highwire.dtl.DTLVardef@1b6b7f3org.highwire.dtl.DTLVardef@e6cc04org.highwire.dtl.DTLVardef@5c4521_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2024

Structural mechanism of FusB-mediated rescue from fusidic acid inhibition of protein synthesis

Antibiotic resistance protein FusB rescues protein synthesis from inhibition by fusidic acid (FA), which locks elongation factor G (EF-G) to the ribosome after GTP hydrolysis. Here, we present time-resolved single-particle cryo-EM structures explaining the mechanism of FusB-mediated rescue. FusB binds to the FA-trapped EF-G on the ribosome, causing large-scale conformational changes of EF-G that break ribosome interactions. This leads to dissociation of EF-G from the ribosome, followed by FA release. We also observe two independent binding sites of FusB on the classical-state ribosome, overlapping with the binding site of EF-G to each of the ribosomal subunits, yet not inhibiting tRNA delivery. Our results reveal an intricate resistance mechanism involving specific interactions of FusB with both EF-G and the ribosome, and a non-canonical release pathway of EF-G.

molecular biology↗

bioRxiv2023

Structures of the Staphylococcus aureus ribosome inhibited by fusidic acid and fusidic acid cyclopentane

The antibiotic fusidic acid (FA) is used to treat Staphylococcus aureus infections. It inhibits protein synthesis by binding to elongation factor G (EF-G) and preventing its release from the ribosome after translocation. While FA is only effective against gram-positive bacteria, the available structures of FA-inhibited complexes are from gram-negative model organisms. To fill this knowledge gap, we solved cryo-EM structures of the S. aureus ribosome in complex with mRNA, tRNA, EF-G and FA to 2.5 [A] resolution and the corresponding complex structures with the recently developed FA derivative FA-cyclopentane (FA-CP) to 2.0 [A] resolution. With both FA variants, the majority of the ribosomal particles are observed in chimeric hybrid state and only a minor population in post-translocational state. As expected, FA binds in a pocket between domains I, II and III of EF-G and the sarcin-ricin loop of 23S rRNA. FA-CP binds in an identical position, but its cyclopentane moiety provides additional contacts to EF-G and 23S rRNA, suggesting that its improved resistance profile towards mutations in EF-G is due to higher-affinity binding. These high-resolution structures reveal new details about the S. aureus ribosome, including confirmation of many rRNA modifications, and provide an optimal starting point for future structure-based drug discovery on an important clinical drug target.

molecular biology↗