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ISSN 1022-7954, Russian Journal of Genetics, 2017, Vol. 53, No. 5, pp. 542–550. © Pleiades Publishing, Inc., 2017.
Original Russian Text © T.M. Grishaeva, Yu.F. Bogdanov, 2017, published in Genetika, 2017, Vol. 53, No. 5, pp. 541–550.
Evolutionary Conservation of Recombination Proteins
and Variability of Meiosis-Specific Proteins of Chromosomes
T. M. Grishaeva* and Yu. F. Bogdanov
Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119991 Russia
*e-mail: grishaeva@vigg.ru
Received June 27, 2016; in final form, October 10, 2016
Abstract⎯A comparison of amino acid sequences is performed for orthologs to the meiosis-specific proteins
in humans and seven other species, including animals, fungi, and plants that serve as models for the study of
molecular mechanisms of meiosis. It is demonstrated that the RAD51 recombination mediator protein is the
most conserved of the studied proteins. Its meiotic homolog DMC1 is less conserved, like the MHL1 mis-
match-repair protein. The meiosis-specific SPO11 endonuclease is the least conserved among the studied
meiotic enzymes. Structural proteins of meiotic chromosomes are poorly conserved. REC8 meiotic cohesin
has 6 times lower similarity in the organisms from different kingdoms than its somatic homolog RAD21. The
intermediate conservation level is characteristic of the synaptonemal complex proteins containing HORMA
domain. Two functional domains of SPO11 endonuclease and MutL
Trans_MLH1 domain of MLH1
enzyme are equally or even less conserved than the whole proteins. HORMA functional domain of a number
of synaptonemal complex proteins is only 2–3 times more conserved than the whole molecule. Thus, among
the key meiotic proteins, the most conserved are proteins responsible for the accuracy of meiotic recombina-
tion. Cohesins, synaptonemal complex proteins, and meiosis-specific SPO11 endonuclease are less con-
served even within their functional domains. Obviously, the meiosis-specific proteins have undergone inde-
pendent evolution in different phylogenetic lineages of eukaryotes.
Keywords: meiosis, proteins, recombination, synaptonemal complex, conservation
DOI: 10.1134/S1022795417040081
INTRODUCTION
Chronologically, meiosis, which is a mandatory
part of sexual process, occupies different places in the
life cycles of plants, fungi, and animals. In spite of this,
cellular and molecular mechanisms of meiosis are
uniform and broadly conserved. Owing to its genetic
role, uniformity of its scheme, and similarity of many
proteins in evolutionarily distant organisms, meiosis is
considered an important field for the study of prob-
lems of evolution at the cellular level.
Genetic recombination and preparing for the seg-
regation of homologous chromosomes are served by a
complex of meiosis-specific proteins that do not func-
tion or are even absent from somatic (vegetative) cells,
dividing by mitosis. Monitoring of mRNA synthesis
(mRNA assay) in yeast Saccharomyces cerevisiae and
spermatocytes of rat Rattus norvegicus showed that, in
these cells, about 1300 proteins are active during mei-
osis, about 300–350 of which being meiosis-specific
[1, 2]. There are meiosis-specific cohesins [3], their
protectors shugoshins [4], synaptonemal complex
proteins [5, 6], and other meiosis-specific proteins.
The main part of meiosis-specific proteins consists of
the recombination proteins, enzymes and modulators
of this process. They are considered the most con-
served [7, 8]. Homologous recombination in meiosis
uses an ancient mechanism of recombinational DNA
repair on the basis of homologous matrix. Recombi-
nation begins with a programmed introduction of
double-strand breaks (DSBs) in the DNA with the
help of meiosis-specific endonucleases. In S. cerevi-
siae and multicellular eukaryotes, it is Spo11/SPO11,
relative to topoisomerase VI of archaeabacteria. The key
proteins of the active phase of homologous recombina-
tion are proteins Rad51/RAD51 and Dmc1/DMC1
that transfer single-stranded DNA ends between the
recombining DNA molecules. Both of these proteins
are homologous to the ancient recombination protein
RecA of bacteria.
In contrast to the recombination/repair proteins,
proteins forming synaptonemal complexes (SCs) are
different in different organisms [5, 9–11]. SCs are the
assistant structures of the meiotic synapsis and recom-
bination of chromosomes. They exist for a limited
time during the meiotic prophase I [11, 12]. SCs are
formed between homologous chromosomes, associate
with meiosis-specific cohesins that connect sister
chromatids, and perform the assistant (scaffold) role
in pairing and recombination of homologous chromo-
somes. The elements of SC ultrastructure are the com-
GENERAL
GENETICS
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