A kirromycin-resistant EF-Tu species reverses streptomycin dependence of Escherichia coli strains mutated in ribosomal protein S12

• Published in: Microbiology (Society for General Microbiology) Vol. 144; no. 12; pp. 3309 - 3316
• Main Authors: Zuurmond, Anne-Marie, Zeef, Leo A. H, Kraal, Barend
• Format: Journal Article
• Language: English
• Published: Reading Soc General Microbiol 01-12-1998; Society for General Microbiology
• Subjects: Anti-Bacterial Agents - metabolism; Anti-Bacterial Agents - pharmacology; Bacteriology; Biological and medical sciences; Cell Division - physiology; Drug Resistance, Microbial; Escherichia coli; Escherichia coli - cytology; Escherichia coli - drug effects; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Genetic Complementation Test; Genetics; Microbiology; Peptide Elongation Factor Tu - genetics; Peptide Elongation Factor Tu - metabolism; Pyridones - pharmacology; Ribosomal Proteins - genetics; Ribosomal Proteins - metabolism; Streptomycin - metabolism; Suppression, Genetic; Antibiotic; Reversion; Streptomycin; Escherichia coli; Dependence; Bacteria; Biosynthesis; Genetical translation; Mutation; Protein; Enterobacteriaceae; Elongation factor EFTu
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-144-12-3309

Leiden Institute of Chemistry, Department of Biochemistry, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
ABSTRACT
Summary: Streptomycin dependence can be caused by mutations in ribosomal protein S12. Mutations suppressing such streptomycin dependence have been found in ribosomal proteins S4 and S5, and in 16S rRNA. Here a new suppressor mutation localized in elongation factor Tu (EF-Tu) is described, consistent with recent models of ribosome-EF-Tu-tRNA interaction at the decoding centre. The EF-Tu mutation was obtained by genetic selection for streptomycin independence; it was identified as Ala375 Thr, previously described as EF-TuA R and known to confer a kirromycin-resistant, error-prone phenotype. Also, other streptomycin-dependent (Sm D ) S12 mutations could be complemented by this mutation. The streptomycin-independent (Sm I ) strain grows more slowly than the wild-type (wt), suggesting that not all the defects of the S12 mutation can be complemented by EF-Tu[A375T]. Moreover, this strain is more susceptible than wt to reduction in the cellular EF-Tu concentration, and disruption of tufB led to considerable growth-rate impairment. Expression of EF-Tu from tufB , not only of wt EF-Tu and EF-Tu[A375T] but, remarkably, also of EF-Tu[G222D], known as EF-TuB 0 and defective in protein synthesis, equally contributed to cell growth. In vitro analysis revealed a decreased translational activity of wt EF-Tu with Sm D ribosomes as compared to EF-Tu[A375T], while EF-Tu[G222D] showed no activity at all, just as with wt ribosomes. Possible mechanisms are discussed for the improved growth rate observed in such Sm I strains when they include wt EF-Tu or EF-Tu[G222D].
Author for correspondence: B. Kraal. Tel: [phone] Fax: [phone]. e-mail: [e-mail]
Keywords: elongation factor Tu, error-prone mutations, rpsL, translational accuracy
Present address: John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.