ISSN:
1572-8773
Keywords:
tRNA
;
tDNA
;
anticodon domain
;
transition metal ion effects
;
spectroscopic characterization
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Biologically active DNA analogs of tRNAPhe (tDNAPhe) were used to investigate metal ion interaction with tRNA-like structures lacking the 2′OH. Binding of Mg2+ to the 76 oligonucleotide tDNAPhe, monitored by circular dichroism spectroscopy, increased base stacking and thus the conformational stability of the molecule. Mg2+ binding was dependent on a d(m5C) in the anticodon region. In contrast to Mg2+, Cd2+ decreased base stacking interactions, thereby destabilizing the molecule. Since alterations in the anticodon region contributed to most of the spectral changes observed, detailed studies were conducted with anticodon hairpin heptadecamers (tDNAAC Phe). The conformation of tDNAAC Phe-d(m5C) in the presence of 1 mm Cd2+, Co2+, Cr2+, Cu2+, Ni2+, Pb2+, VO2+ or Zn2+ differed significantly from that of the biologically active structure resulting from interaction with Mg2+, Mn2+ or Ca2+. Nanomolar concentrations of the transition metals were sufficient to denature the tDNAAC Phe-d(m5C) structure without catalyzing cleavage of the oligonucleotide. In the absence of Mg2+ and at [Cd2+] to [tDNAAc Phe-d(m5C)] ratios of approximately 0.2–1.0, tDNAAC Phe-d(m5C40) formed a stable conformation with one Cd2+ bound with a K d = 3.7 × 10-7. In contrast to Mg2+, Cd2+ altered the DNA analogs without discriminating between modified and unmodified tDNAAC Phe. This ability of transition metals to disrupt higher order DNA structures, and possibly RNA, at μM concentrations, in vitro, demonstrates that these structures are potential targets in chronic metal exposure, in vivo.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00141601
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