NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
DNA CTG triplet repeats involved in dynamic mutations of neurologically related gene sequences form stable duplexesDNA triplet repeats, 5'-d(CTG)n and 5'-d(CAG)n, are present in genes which have been implicated in several neurodegenerative disorders. To investigate possible stable structures formed by these repeating sequences, we have examined d(CTG)n, d(CAG)n and d(CTG).d(CAG)n (n = 2 and 3) using NMR and UV optical spectroscopy. These studies reveal that single stranded (CTG)n (n > 2) forms stable, antiparallel helical duplexes, while the single stranded (CAG)n requires at least three repeating units to form a duplex. NMR and UV melting experiments show that the Tm increases in the order of [(CAG)3]2 < [(CTG)3]2 << (CAG)3.(CTG)3. The (CTG)3 duplex is stable and exhibits similar NMR spectra in solutions containing 0.1-4 M NaCl and at a pH range from 4.6 to 8.8. The (CTG)3 duplex, which contains multiple-T.T mismatches, displays many NMR spectral characteristics similar to those of B-form DNA. However, unique NOE and 1H-31P coupling patterns associated with the repetitive T.T mismatches in the CTG repeats are discerned. These results, in conjunction with recent in vitro studies suggest that longer CTG repeats may form hairpin structures, which can potentially cause interruption in replication, leading to dynamic expansion or deletion of triplet repeats.
Document ID
20040173336
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Smith, G. K.
(University of Houston TX 77204-5641, United States)
Jie, J.
Fox, G. E.
Gao, X.
Date Acquired
August 22, 2013
Publication Date
November 11, 1995
Publication Information
Publication: Nucleic acids research
Volume: 23
Issue: 21
ISSN: 0305-1048
Subject Category
Exobiology
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Exobiology

Available Downloads

There are no available downloads for this record.
No Preview Available