Functional interactions of an Escherichia coli ribosomal ATPase.
The gene encoding ribosome-bound ATPase (RbbA), which occurs bound to 70S ribosomes and 30S subunits, has been identified. The amino-acid sequence of RbbA reveals the presence of two ATP-binding domains in the N-terminal half of the protein. RbbA harbors an intrinsic ATPase activity that is stimulated by both 70S ribosomes and 30S subunits. Here we show that purified recombinant RbbA markedly stimulates polyphenylalanine synthesis in the presence of the elongation factors Tu and G (EF-Tu and EF-G) and that the hydrolysis of ATP by RbbA is required to stimulate synthesis. RbbA is reported to have affinity for EF-Tu but not for EF-G. Additionally, RbbA copurifies with 30S ribosomal subunits and can be crosslinked to the ribosomal protein S1. Studies using a spectrum of antibiotics, including some of similar function, revealed that hygromycin, which binds to the 30S subunit, has a significant effect on the ATPase activity and on the affinity of RbbA for ribosomes. A possible role for RbbA in protein-chain elongation is proposed.
Kiel
M C
MC
Banting and Best Department of Medical Research, University of Toronto, 112 College Street, ON, Canada M5G 1L6.
Ganoza
M C
MC
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D002934:Cinnamates; D003432:Cross-Linking Reagents; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D006921:Hygromycin B / Q000031:analogs & derivatives / Q000494:pharmacology; D010441:Peptide Chain Elongation, Translational; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000201:enzymology*
D001426:Bacterial Proteins; D002934:Cinnamates; D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D012269:Ribosomal Proteins; C015494:ribosomal protein S1; D006921:Hygromycin B; C026273:hygromycin A; D000251:Adenosine Triphosphatases; D010444:Peptide Elongation Factor Tu; C422450:RbbA protein, E coli