A minimum structure of aminoglycosides that causes an initiation shift of trans-translation.
Trans-translation is an unusual translation in which transfer-messenger RNA plays a dual function--as a tRNA and an mRNA--to relieve the stalled translation on the ribosome. It has been shown that paromomycin, a typical member of a 4,5-disubstituted class of aminoglycosides, causes a shift of the translation-resuming point on the tmRNA by -1 during trans-translation. To address the molecular basis of this novel effect, we examined the effects of various aminoglycosides that can bind around the A site of the small subunit of the ribosome on trans-translation in vitro. Tobramycin and gentamicin, belonging to the 4,6-disubstituted class of aminoglycosides having rings I and II similar to those in the 4,5-disubstituted class, possess similar effects. Neamine, which has only rings I and II, a common structure shared by 4,5- and 4,6-disubstituted classes of aminoglycosides, was sufficient to cause an initiation shift of trans-translation. In contrast, streptomycin or hygromycin B, lacking ring I, did not cause an initiation shift. The effect of each aminoglycoside on trans-translation coincides with that on conformational change in the A site of the small subunit of the ribosome revealed by recent structural studies: paromomycin, tobramycin and geneticin which is categorized into the gentamicin subclass, but not streptomycin and hygromycin B, flip out two conserved adenine bases at 1492 and 1493 from the A site helix. The pattern of initiation shifts by paromomycin fluctuates with variation of mutations introduced into a region upstream of the initiation point.
Department of Biochemistry and Biotechnology, Faculty of Agriculture and Life Science Hirosaki University, Hirosaki 036-8561, Japan.
Takayuki
T
Konno
Toshiharu
T
Takahashi
Daisuke
D
Kurita
Akira
A
Muto
Hyouta
H
Himeno
D000617:Aminoglycosides / Q000737:chemistry* / Q000494:pharmacology*; D018965:Frameshifting, Ribosomal; D005601:Framycetin; D006921:Hygromycin B / Q000737:chemistry / Q000494:pharmacology; D009154:Mutation; D010303:Paromomycin / Q000737:chemistry / Q000494:pharmacology; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics*; D013307:Streptomycin / Q000737:chemistry / Q000494:pharmacology
D000617:Aminoglycosides; D012329:RNA, Bacterial; C096222:tmRNA; D006921:Hygromycin B; D005601:Framycetin; C488396:neamine; D010303:Paromomycin; D013307:Streptomycin