Effect of zinc ions on tRNA structure: imino proton NMR spectroscopy
The structure of tRNA in solution was explored by NMR spectroscopy to evaluate the effect of divalent cations, especially zinc, which has a profound effect on the chromatographic behavior of tRNAs in certain systems. The divalent ions Mg/sup 2 +/ and Zn/sup 2 +/ have specific effects on the imino proton region of the /sup 1/H NMR spectrum of valine transfer RNA (tRNA/sup Val/) of Escherichia coli and of phenylalanine transfer RNA (tRNA/sup Phe/) of yeast. The dependence of the imino proton spectra of the two tRNAs was examined as a function of Zn/sup 2 +/ concentration. In both tRNAs the tertiary base pair (G-15) x (C-48) was markedly affected by Zn/sup 2 +/ (shifted downfield possibly by as much as 0.4 ppm); this is the terminal base pair in the augmented dihydrouridine helix (D-helix). Base pair (U-8) x (A-14) in yeast tRNA/sup Phe/ or (s/sup 4/U-8) x (A-14) in tRNA/sub 1//sup Val/, which are stacked on (G-15) x (C-48), was not affected by Zn/sup 2 +/, except when 1-2 Mg/sup 2 +/ ions per tRNA were also present. Another imino proton that may be affected by Zn/sup 2 +/ in both tRNAs is that of the tertiary base pair (G-19) x (C-46). The assignment of this resonance in yeast tRNA/sup Phe/ is tentative since it is located in the region of highly overlapping resonances between 12.6 and 12.3 ppm. This base pair helps to anchor the D-loop to the T Psi C loop. Surprisingly, the imino proton of (G-18) x (Psi-55) is not similarly affected by Zn/sup 2 +/, indicating that the effect of Zn/sup 2 +/ is not on G-57 which is the central non-hydrogen-bonded base in the guanosine sandwich created by the stacking of G-19, G-57, and G-20. The solution structure of tRNA/sup Phe/ shows marked correlation to the crystal structure in terms of Zn/sup 2 +/ interactions.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7187481
- Journal Information:
- Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 27:15; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Kinetics for exchange of imino protons in the d(C-G-C-G-A-A-T-T-C-G-C-G) double helix and in two similar helices that contain a G x T base pair, d(C-G-T-G-A-A-T-T-C-G-C-G), and an extra adenine, d(C-G-C-A-G-A-A-T-T-C-G-C-G)
Structure of an unmodified tRNA molecule
Related Subjects
560300 -- Chemicals Metabolism & Toxicology
62 RADIOLOGY AND NUCLEAR MEDICINE
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METAL COMPOUNDS
BACTERIA
BARYONS
BIOLOGICAL EFFECTS
CATIONS
CHARGED PARTICLES
CHEMICAL SHIFT
ELEMENTARY PARTICLES
ESCHERICHIA COLI
FERMIONS
HADRONS
IONS
MAGNESIUM COMPOUNDS
MAGNETIC RESONANCE
MICROORGANISMS
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
NUCLEIC ACIDS
NUCLEONS
ORGANIC COMPOUNDS
PROTONS
RESONANCE
RNA
TRANSFER RNA
ZINC COMPOUNDS