Minimal 16S rRNA binding site and role of conserved nucleotides in Escherichia coli ribosomal protein S8 recognition

Abstract Excision and transposition of the Tn5 element in Escherichia coli ordinarily appear to occur by recA-independent mechanisms. However, recA(Prtc) genes, which encode RecA proteins that are constitutively activated to the protease state, greatly enhanced excision and transposition; both events appeared to occur concomitantly and without destruction of the donor DNA. The recombinase function of the RecA protein was not required. Transposition was accompanied by partial, and occasionally full, restoration of the functional integrity of the gene vacated by the excised Tn5. The stimulation of transposition was inhibited by an uncleavable LexA protein and was strongly enhanced by an additional role of the RecA(Prtc) protein besides its mediation of LexA cleavage. To account for the enhanced transposition, we suggest that (i) there may be a LexA binding site within the promoter for the IS50 transposase, (ii) activated RecA may cleave the IS50 transposition inhibitor, and (iii) the transposase may be formed by RecA cleavage of a precursor molecule.

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Mutational and Structural Analysis of the RNA Binding Site for Escherichia coli Ribosomal Protein S7

Journal of Molecular Biology ◽

10.1006/jmbi.1994.1705 ◽

1994 ◽

Vol 244 (1) ◽

pp. 74-85 ◽

Cited By ~ 14

Author(s):

François Dragon ◽

Catherine Payant ◽

Léa Brakier-Gingras

Keyword(s):

Escherichia Coli ◽

Structural Analysis ◽

Ribosomal Protein ◽

Binding Site ◽

Rna Binding

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16S rRNA Mutations That Confer Tetracycline Resistance in Helicobacter pylori Decrease Drug Binding in Escherichia coli Ribosomes

Journal of Bacteriology ◽

10.1128/jb.187.11.3708-3712.2005 ◽

2005 ◽

Vol 187 (11) ◽

pp. 3708-3712 ◽

Cited By ~ 27

Author(s):

Lisa Nonaka ◽

Sean R. Connell ◽

Diane E. Taylor

Keyword(s):

Escherichia Coli ◽

Helicobacter Pylori ◽

16S Rrna ◽

Binding Site ◽

Tetracycline Resistance ◽

Drug Binding ◽

Multicopy Plasmid ◽

Wild Type ◽

E Coli ◽

H Pylori

ABSTRACT Tetracycline resistance in clinical isolates of Helicobacter pylori has been associated with nucleotide substitutions at positions 965 to 967 in the 16S rRNA. We constructed mutants which had different sequences at 965 to 967 in the 16S rRNA gene present on a multicopy plasmid in Escherichia coli strain TA527, in which all seven rrn genes were deleted. The MICs for tetracycline of all mutants having single, double, or triple substitutions at the 965 to 967 region that were previously found in highly resistant H. pylori isolates were higher than that of the mutant exhibiting the wild-type sequence of tetracycline-susceptible H. pylori. The MIC of the mutant with the 965TTC967 triple substitution was 32 times higher than that of the E. coli mutant with the 965AGA967 substitution present in wild-type H. pylori. The ribosomes extracted from the tetracycline-resistant E. coli 965TTC967 variant bound less tetracycline than E. coli with the wild-type H. pylori sequence at this region. The concentration of tetracycline bound to the ribosome was 40% that of the wild type. The results of this study suggest that tetracycline binding to the primary binding site (Tet-1) of the ribosome at positions 965 to 967 is influenced by its sequence patterns, which form the primary binding site for tetracycline.

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