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Modulation of Psoralen DNA Crosslinking Kinetics Associated with a Triplex‐forming Oligonucleotide
Author(s) -
Oh Dennis H.,
Suzara Vincent,
Krishnan Rajagopal
Publication year - 2007
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2007.00243.x
Subject(s) - psoralen , oligonucleotide , chemistry , dna , kinetics , stereochemistry , biophysics , biochemistry , biology , physics , quantum mechanics
A triplex‐forming oligonucleotide (TFO), HPRT3, conjugated to a psoralen derivative, was designed to target a psoralen reaction site within the HPRT gene. HPRT3 bound with high affinity to a synthetic duplex target sequence. At a uniform UVA radiation dose, the ratio of psoralen monoadducts (MA) to interstrand crosslinks decreased and inverted with increasing TFO concentration. As the TFO concentration increased from 10 n m to 10 μ m , the efficiency of psoralen MA formation remained relatively constant but the efficiency of interstrand crosslink formation increased several‐fold. Neither shortening the TFO to reduce its dissociation constant nor altering the DNA sequences flanking the TFO binding site altered the concentration dependence of MA and crosslink yields. The psoralen photokinetics associated with 10 n m HPRT3 converted to those associated with 10 μ m HPRT3 with the addition of other unrelated TFOs at 10 μ m that do not specifically interact with the HPRT3 target sequence. Glycerol at concentrations of 0.5% (vol/vol) or higher also mimicked high TFO concentrations in enhancing crosslink formation. These results demonstrate that while psoralen may be targeted to react at a particular sequence by TFOs, photoreactivity associated with triplex formation is also modulated by sequence‐independent factors that may affect the local macromolecular environment.