Novel plasmid-mediated 16S rRNA m1A1408 methyltransferase, NpmA, found in a clinically isolated Escherichia coli strain resistant to structurally diverse aminoglycosides. (1/61)

We have isolated a multiple-aminoglycoside-resistant Escherichia coli strain, strain ARS3, and have been the first to identify a novel plasmid-mediated 16S rRNA methyltransferase, NpmA. This new enzyme shared a relatively low level of identity (30%) to the chromosomally encoded 16S rRNA methyltransferase (KamA) of Streptomyces tenjimariensis, an actinomycete aminoglycoside producer. The introduction of a recombinant plasmid carrying npmA could confer on E. coli consistent resistance to both 4,6-disubstituted 2-deoxystreptamines, such as amikacin and gentamicin, and 4,5-disubstituted 2-deoxystreptamines, including neomycin and ribostamycin. The histidine-tagged NpmA elucidated methyltransferase activity against 30S ribosomal subunits but not against 50S subunits and the naked 16S rRNA molecule in vitro. We further confirmed that NpmA is an adenine N-1 methyltransferase specific for the A1408 position at the A site of 16S rRNA. Drug footprinting data indicated that binding of aminoglycosides to the target site was apparently interrupted by methylation at the A1408 position. These observations demonstrate that NpmA is a novel plasmid-mediated 16S rRNA methyltransferase that provides a panaminoglycoside-resistant nature through interference with the binding of aminoglycosides toward the A site of 16S rRNA through N-1 methylation at position A1408.  (+info)

The effect of mutated mitochondrial ribosomal proteins S16 and S22 on the assembly of the small and large ribosomal subunits in human mitochondria. (2/61)

 (+info)

Amebic colitis in an antigenically and serologically negative patient: usefulness of a small-subunit ribosomal RNA gene-based polymerase chain reaction in diagnosis. (3/61)

 (+info)

Structural dynamics of the ribosome. (4/61)

 (+info)

Roles of the N- and C-terminal domains of mammalian mitochondrial initiation factor 3 in protein biosynthesis. (5/61)

 (+info)

Unusual Cryptosporidium genotypes in human cases of diarrhea. (6/61)

 (+info)

Group I introns and associated homing endonuclease genes reveals a clinal structure for Porphyra spiralis var. amplifolia (Bangiales, Rhodophyta) along the Eastern coast of South America. (7/61)

 (+info)

rRNA suppressor of a eukaryotic translation initiation factor 5B/initiation factor 2 mutant reveals a binding site for translational GTPases on the small ribosomal subunit. (8/61)

 (+info)