Download MendeleyMechanism of elongation factor-G-mediated fusidic acid resistance and fitness compensation in Staphylococcus aureus.
Koripella, R.K., Chen, Y., Peisker, K., Koh, C.S., Selmer, M., Sanyal, S.(2012) J Biol Chem 287: 30257-30267
- PubMed: 22767604
- DOI: https://doi.org/10.1074/jbc.M112.378521
- Primary Citation of Related Structures:
3ZZ0, 3ZZT, 3ZZU - PubMed Abstract:
Antibiotic resistance in bacteria is often associated with fitness loss, which is compensated by secondary mutations. Fusidic acid (FA), an antibiotic used against pathogenic bacteria Staphylococcus aureus, locks elongation factor-G (EF-G) to the ribosome after GTP hydrolysis. To clarify the mechanism of fitness loss and compensation in relation to FA resistance, we have characterized three S. aureus EF-G mutants with fast kinetics and crystal structures. Our results show that a significantly slower tRNA translocation and ribosome recycling, plus increased peptidyl-tRNA drop-off, are the causes for fitness defects of the primary FA-resistant mutant F88L. The double mutant F88L/M16I is three to four times faster than F88L in both reactions and showed no tRNA drop-off, explaining its fitness compensatory phenotype. The M16I mutation alone showed hypersensitivity to FA, higher activity, and somewhat increased affinity to GTP. The crystal structures demonstrate that Phe-88 in switch II is a key residue for FA locking and also for triggering interdomain movements in EF-G essential for its function, explaining functional deficiencies in F88L. The mutation M16I loosens the hydrophobic core in the G domain and affects domain I to domain II contact, resulting in improved activity both in the wild-type and F88L background. Thus, FA-resistant EF-G mutations causing fitness loss and compensation operate by affecting the conformational dynamics of EF-G on the ribosome.
Organizational Affiliation:
Department of Cell and Molecular Biology, Uppsala University, 75124 Uppsala, Sweden.
