ISSN 1022-7954, Russian Journal of Genetics, 2006, Vol. 42, No. 4, pp. 363–375. © Pleiades Publishing, Inc., 2006.
Original Russian Text © E.V. Chmuzh, L.A. Shestakova, V.S. Volkova, I.K. Zakharov, 2006, published in Genetika, 2006, Vol. 42, No. 4, pp. 462–476.
Prokaryotic and eukaryotic cells both possess sys-
tems that repair damaged DNA. There are different
repair mechanisms, which are implemented by means
of different enzyme sets.
DNA repair was discovered in 1949, when Kelner
and Dulbecco independently described the phenome-
non of photoreactivation [1, 2].
The studies of DNA repair mechanisms in
started in the second half of the 20th century,
when the ﬁrst repair-deﬁcient mutant ﬂies were pro-
duced. First, so-called meiotic mutants (
) were dis-
. They exhibited
low frequency of meiotic recombination [3, 4]. Later,
mutants sensitive to the action of different mutagens
were found [5–7]. These mutants are collectively
known as mutagen-sensitive mutants (
). Most of
mutants are characterized by hypersensitivity to the
action of mutagens. On the contrary,
defective in meiotic recombination system . Both
groups of phenotypic manifestations are determined by
defects in different protein systems involved in DNA
damage repair. As a result, a large set of repair system
mutants was obtained. DNA repair genes and proteins
are multifunctional, which is evidenced by simulta-
neous manifestation of
phenotypes in the
mutants, as well as by substantial abnormalities of
mitotic chromosomes behavior discovered in many of
the mutants [9, 10].
Further investigations in this area supported the idea
that repair proteins are also involved in replication,
transcription, recombination, regulation of cell cycle,
and regulate position variegation effect [11–15]. It was
demonstrated that some of DNA repair genes partici-
pated in transposition of mobile genetic elements, as
well as in insertional mutagenesis as a whole [16–19].
Induced transposition of certain mobile elements in
some mutagen-sensitive mutants results in manifesta-
tion of the phenotypes analogous to those induced by
physical and chemical mutagens. The effect of certain
mutagen-sensitive mutations on the mutation rate of
unstable insertion alleles in
Note that, since rapid and timely cellular response to
DNA damage is vitally important, many pathways of
DNA repair exist. These pathways overlap, forming a
complex, but strictly controlled repair machinery. How-
ever, many details of these interactions still remain
In this review we present a description and classiﬁ-
cation of different DNA damage repair mechanisms in
and consider the protein sys-
tems involved in these processes.
DIVERSE MECHANISMS OF DNA REPAIR
Direct Correction of Mutation Lesions
Direct correction of mutational lesions is repair of
the lesions without nucleotide excision. It is effected by
the simplest repair mechanisms, operating without
recruiting complex protein systems. For example, DNA
repair by means of checking DNA with DNA poly-
merase may be attributed to this group. Such processes,
however, are usually referred to as the pre-repair events,
since this system is active only at the level of replica-
tion, providing high ﬁdelity of DNA synthesis.
True repair events are represented by photoreactiva-
tion, i.e., destruction of pyrimidine dimers upon expo-
sure to visible light. This process is catalyzed by pho-
tolyase, an enzyme, encoded by gene
which is acti-
vated by light photons and destroys pyrimidine dimers.
Photolyase was found in prokaryotes, lower eukaryotes,
), and in many verte-
brates. Humans, however, lack this enzyme [20–23].
Diversity of Mechanisms and Functions of Enzyme Systems
of DNA Repair in
E. V. Chmuzh
, L. A. Shestakova
, V. S. Volkova
, and I. K. Zakharov
Novosibirsk State University, Department of Cytology and Genetics, Novosibirsk, 630090 Russia
Institute of Cytology and Genetics, Russian Academy of Sciences, Novosibirsk, 630090 Russia;
fax: 8(383)333-12-78; e-mail: firstname.lastname@example.org
Received August 28, 2005
—The review presents a description and comparative analysis of the known enzymatic systems of
DNA repair in
. Data on protein products, mechanisms of action, and the involvement
of the repair system elements in other cellular processes are summarized.