ISSN 1022-7954, Russian Journal of Genetics, 2006, Vol. 42, No. 7, pp. 737–743. © Pleiades Publishing, Inc., 2006.
Original Russian Text © S.V. Vasilieva, E.Ju. Moschkovskaya, A.S. Terekhov, N.A. Sanina, S.M. Aldoschin, 2006, published in Genetika, 2006, Vol. 42, No. 7, pp. 904–911.
Nitric oxide (NO) is a universal regulator of impor-
tant functions in living organisms. Initially, NO was
identiﬁed as a potent regulator of physiological pro-
cesses and cell immunity  and NO-donating agents
received wide acceptance as drugs (nitroglycerin).
More recent studies have shown that, in addition to
these functions, NO is involved in long-term genetic
processes such as regulation of the genetic apparatus at
the levels of transcription and mRNA translation, apo-
ptosis, cell differentiation, ontogeny, and others . In
the bacterial cell, NO acts as a signal molecule in stress
resistance pathways and activates expression of the
genes belonging to important DNA repair systems:
SoxRS , OxyR , SOS , and Ada . Structural,
functional, and regulatory analogs of these systems have
been found in mammalian, including human, cells .
SH groups and [Fe–S] clusters of proteins are the
major targets of NO and its donors upon their interac-
tions with biological molecules . The NO donors S-
nitrosoglutathione (GSNO) and S-nitrosopenicillamine
inhibit the repair enzyme O
methyltransferase and thereby increase the sensibility
of mammalian cells to alkylating carcinolythics .
NO and its donors (nitroglycerin, GSNO, etc.) are
capable of direct interactions with DNA and cause
mutations at certain concentrations [10–13].
NO is highly reactive and unstable and, probably,
occurs in the organism mostly in the form of its donors
S-nitrosothiols and nitrosyl iron complexes, which
maintain the intracellular NO pool and ensure NO
transport [1, 14].
We were the ﬁrst to synthesize crystal NO donors
with various ligands, including water-soluble agents
[15, 16]. These compounds are characterized by a rela-
tively low cytotoxicity and ensure the signaling in
genetic systems of cell resistance to various stress fac-
tors [17, 18].
Since many biological systems depend on iron as a
redox cofactor, much attention has been attracted to the
cell response to partial or complete depletion of iron,
especially with regard to the processes regulated by
NO. Iron is absolutely indispensable for the normal cell
cycle: in its absence, mitosis is arrested and apoptosis
is induced. Yeasts have a genetic mechanism that coor-
dinates the regulation of Fe-dependent metabolic path-
ways, whose enzymes usually contain [Fe–S] clusters.
This mechanism involves targeted degradation of spe-
ciﬁc mRNAs and ensures the optimal use of intracellu-
lar iron when its pool is limited . Iron deﬁciency
increases expression of the
gene in mammalian
cells, which suppresses the growth-regulating mecha-
nisms and leads to metastasis.
The objectives of this work were to study the effect
of intracellular iron on the genetic, including
mutagenic, activity of crystal NO donors with natural
and synthetic ligands and to correlate this activity with
their physico-chemical characteristics. Our interest in
Intracellular Iron Ions Regulate the Genetic Activity
of NO-Donating Agents
S. V. Vasilieva
, E. Ju. Moschkovskaya
, A. S. Terekhov
N. A. Sanina
, and S. M. Aldoschin
Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Moscow, 119334 Russia;
Institute of Problems of Chemical Physics, Russian Academy of Sciences,
Chernogolovka, Moscow oblast, 142432 Russia
Received July 14, 2005; in ﬁnal form, December 22, 2005
—This work is a part of a directional search for new crystal donors of nitric oxide (NO), which are
promising for complex chemotherapy. The relationships between the physico-chemical properties of NO
donors, their genotoxic and mutagenic activities, and the dependence on intracellular iron were studied. New
crystal NO donors (di- and trinitrosyl iron complexes with synthetic ligands) were examined for the ﬁrst time
and compared with known NO donors containing natural ligands. All but one compound induced expression of
Escherichia coli sﬁA
gene belonging to the SOS regulon and exerted a mutagenic effect on
TA1535. These effects were fully or signiﬁcantly inhibited by the iron(II)-chelating agent o-phenan-
throlin, depending on the mono- or binuclear structure of the ligands. The rate of donating free NO in solution
did not positively correlate with the genotoxic activity of the crystal NO donors. The genetic activity of all NO
donors proved to depend on intracellular iron.