Structure and function of FusB: an elongation factor G-binding fusidic acid resistance protein active in ribosomal translocation and recycling.
Fusidic acid (FA) is a bacteriostatic antibiotic that locks elongation factor G (EF-G) to the ribosome after GTP hydrolysis during elongation and ribosome recycling. The plasmid pUB101-encoded protein FusB causes FA resistance in clinical isolates of Staphylococcus aureus through an interaction with EF-G. Here, we report 1.6 and 2.3 Å crystal structures of FusB. We show that FusB is a two-domain protein lacking homology to known structures, where the N-terminal domain is a four-helix bundle and the C-terminal domain has an alpha/beta fold containing a C4 treble clef zinc finger motif and two loop regions with conserved basic residues. Using hybrid constructs between S. aureus EF-G that binds to FusB and Escherichia coli EF-G that does not, we show that the sequence determinants for FusB recognition reside in domain IV and involve the C-terminal helix of S. aureus EF-G. Further, using kinetic assays in a reconstituted translation system, we demonstrate that FusB can rescue FA inhibition of tRNA translocation as well as ribosome recycling. We propose that FusB rescues S. aureus from FA inhibition by preventing formation or facilitating dissociation of the FA-locked EF-G-ribosome complex.
Department of Cell and Molecular Biology, BMC, P.O. Box 596, SE 751 24, Uppsala, Sweden.
Xiaohu
X
Guo
Kristin
K
Peisker
Kristina
K
Bäckbro
Yang
Y
Chen
Ravi Kiran
RK
Koripella
Chandra Sekhar
CS
Mandava
Suparna
S
Sanyal
Maria
M
Selmer
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D005672:Fusidic Acid / Q000494:pharmacology*; D008969:Molecular Sequence Data; D020653:Peptide Elongation Factor G / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D054681:Ribosome Subunits, Large, Bacterial / Q000235:genetics; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C492443:FusB protein, Staphylococcus aureus; D020653:Peptide Elongation Factor G; D005672:Fusidic Acid