| Autor: |
Hans A. Heus, C.A.G. Haasnoot, J.M.A. Van Kimmenade, S.H. de Bruin, C.W. Hilbers, P.H. Van Knippenberg |
| Rok vydání: |
1983 |
| Předmět: |
|
| Zdroj: |
Journal of Molecular Biology. 170:939-956 |
| ISSN: |
0022-2836 |
| DOI: |
10.1016/s0022-2836(83)80197-1 |
| Popis: |
The "colicin" fragments comprising the 49 3'-terminal nucleotides of 16 S ribosomal RNA have been isolated from wild-type Escherichia coli and from a kasugamycin-resistant mutant that lacks methylation of two geminal adenine residues. Proton nuclear magnetic resonance (n.m.r.) spectra (500 MHz) were recorded at various temperatures. The low-field resonances arising from the hydrogen-bonded iminoprotons of paired bases were assigned using the nuclear Overhauser effect (n.o.e.). Crucial to the interpretation of the spectra are the resonances that originate from the two hydrogen-bonded iminoprotons of a U X G basepair. Combined with temperature-jump relaxation kinetics experiments the n.o.e.s lead to the conclusion that a conserved A X U/U X G junction in the hairpin is a thermolabile dislocation in the helix. The n.m.r. spectra of the wild-type and mutant fragment are only different with respect to the iminoproton resonances of the two base-pairs adjoining the hairpin loop. The spectra recorded at various temperatures tend to indicate that dimethylation of the adenosines labilizes these base-pairs, but no definitive conclusions are drawn. The results confirm our previous views that dimethylation of the adenosine residues affects the conformation of the hairpin loop. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
