The conserved GTPase HflX is a ribosome splitting factor that binds to the E-site of the bacterial ribosome
Coatham, Mackenzie L.
Brandon, Harland E.
Fischer, Jeffrey J.
Oxford University Press
Using a combination of biochemical, structural probing and rapid kinetics techniques we reveal for the first time that the universally conserved translational GTPase (trGTPase) HflX binds to the E-site of the 70S ribosome and that its GTPase activity is modulated by peptidyl transferase centre (PTC) and peptide exit tunnel (PET) binding antibiotics, suggesting a previously undescribed mode of action for these antibiotics. Our rapid kinetics studies reveal that HflX functions as a ribosome splitting factor that disassembles the 70S ribosomes into its subunits in a nucleotide dependent manner. Furthermore, our probing and hydrolysis studies show that the ribosome is able to activate trGTPases bound to its E-site. This is, to our knowledge, the first case in which the hydrolytic activity of a translational GTPase is not activated by the GTPase activating centre (GAC) in the ribosomal A-site. Furthermore, we provide evidence that the bound state of the PTC is able to regulate the GTPase activity of E-site bound HflX.
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GTPase , Guanosine triphosphatase , Ribosomes , Ribosome , E-site , Splitting factor , Antibiotics , HflX
Coatham, M.L., Brandon, H.E., Fischer, J.J., Schummer, T., & Wieden, H. (2016). The conserved GTPase HflX is a ribosome splitting factor that binds to the E-site of the bacterial ribosome. Nucleic Acids Research, 44(4), 1952-1963. doi:10.1093/nar/gkv1524