Modified Aminoglycosides Bind Nucleic Acids in High-Molecular-Weight Complexes.

Aminoglycosides represent a large group of antibiotics well known for their ability to target the bacterial ribosome. In studying 6"-substituted variants of the aminoglycoside tobramycin, we serendipitously found that compounds with C or C linear alkyl substituents potently inhibit reverse transcription in vitro. Initial observations suggested specific inhibition of reverse transcriptase.

Roles of specific aminoglycoside-ribosome interactions in the inhibition of translation.

Aminoglycosides containing a 2-deoxystreptamine core (AGs) represent a large family of antibiotics that target the ribosome. These compounds promote miscoding, inhibit translocation, and inhibit ribosome recycling. AG binding to helix h44 of the small subunit induces rearrangement of A-site nucleotides A1492 and A1493, which promotes a key open-to-closed conformational change of the subunit and thereby increases miscoding.

Epistasis analysis of 16S rRNA ram mutations helps define the conformational dynamics of the ribosome that influence decoding.

The ribosome actively participates in decoding, with a tRNA-dependent rearrangement of the 30S A site playing a key role. Ribosomal ambiguity (ram) mutations have mapped not only to the A site but also to the h12/S4/S5 region and intersubunit bridge B8, implicating other conformational changes such as 30S shoulder rotation and B8 disruption in the mechanism of decoding. Recent crystallographic data have revealed that mutation G299A in helix h12 allosterically promotes B8 disruption, raising the question of whether G299A and/or other ram mutations act mainly via B8.

Modification of targets related to the Entner-Doudoroff/pentose phosphate pathway route for methyl-D-erythritol 4-phosphate-dependent carotenoid biosynthesis in Escherichia coli.

Background: In engineered strains of Escherichia coli, bioconversion efficiency is determined by not only metabolic flux but also the turnover efficiency of relevant pathways. Methyl-D-erythritol 4-phosphate (MEP)-dependent carotenoid biosynthesis in E. coli requires efficient turnover of precursors and balanced flux among precursors, cofactors, and cellular energy.