Ribosome binding of DNA analogs of tRNA requires base modifications and supports the "extended anticodon".
The efficiency of translation depends on correct tRNA-ribosome interactions. The ability of chemically synthesized yeast tRNA(Phe) anticodon domains to effectively inhibit the binding of native yeast tRNA(Phe) to poly(U)-programmed Escherichia coli 30S ribosomal subunits was dependent on a Mg(2+)-stabilized stem and an open anticodon loop, both facilitated by base modifications. Analysis of tRNA sequences has revealed that base modifications which negate canonical hydrogen bonding are found in 95% of those tRNA anticodon loop sequences with the potential to form two Watson-Crick base pairs across the loop. Therefore, we postulated that a stable anticodon stem and an open loop are prerequisites for ribosome binding. To test this hypothesis, DNA analogs of the yeast tRNA(Phe) anticodon domain were designed to have modification-induced, Mg(2+)-stabilized stems and open loops. The unmodified DNA analog neither bound to poly(U)-programmed 30S ribosomal subunits nor inhibited the binding of native tRNA(Phe). However, specifically modified DNA analogs did bind to ribosomal subunits and effectively inhibited tRNA(Phe) from binding. Thus, modification-dependent Mg(2+)-stabilized anticodon domain structures with open loops have evolved as the preferred anticodon conformations for ribosome binding.
Dao
V
V
Department of Biochemistry, North Carolina State University, Raleigh 27695-7622.
Guenther
R
R
Malkiewicz
A
A
Nawrot
B
B
Sochacka
E
E
Kraszewski
A
A
Jankowska
J
J
Everett
K
K
Agris
P F
PF
D000926:Anticodon; D001482:Base Composition; D001483:Base Sequence; D004269:DNA, Bacterial / Q000378:metabolism*; D006860:Hydrogen Bonding; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000378:metabolism; D011072:Poly U / Q000378:metabolism; D014176:Protein Biosynthesis; D012329:RNA, Bacterial; D012360:RNA, Transfer, Phe / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism*
D000926:Anticodon; D004269:DNA, Bacterial; D009705:Nucleosides; D012329:RNA, Bacterial; D012360:RNA, Transfer, Phe; D011072:Poly U; D008274:Magnesium