ISSN 1022-7954, Russian Journal of Genetics, 2007, Vol. 43, No. 1, pp. 29–34. © Pleiades Publishing, Inc., 2007.
Original Russian Text © G.A. Zhouravleva, O.M. Zemlyanko, C. Le Goff, A. V. Petrova, M. Philippe, S.G. Inge-Vechtomov, 2007, published in Genetika, 2007, Vol. 43, No. 1,
Translation termination factors eRF1 and eRF3
form a complex both in vivo and in vitro (for a review,
see [1–3]). In yeast
factors are encoded by the
genes, respectively [4–8]. Mutations of these genes
reduce the efﬁciency of translation termination, act as
omnipotent nonsense suppressors, and cause various
pleiotropic effects (for a review, see ).
The spatial structure of eRF1 resembles that of
tRNA [9, 10]. All known proteins of the eRF1 family are
evolutionarily and functionally conserved. It has been
found that eRF1 of higher eukaryotes can substitute the
homologous yeast termination factor in vivo .
The other factor, eRF3, acts as an eRF1- and ribo-
some-dependent GTPase and activates eRF1 [12, 13].
Proteins of the eRF3 family each have three structural
domains (for a review, see ). The C-terminal (C)
domains of all eRF3 examined are highly conserved in
both related and evolutionary distant species. In
, the C domain of eRF3 is necessary and sufﬁ-
cient for cell viability; it is this domain that ensures
translation termination . The middle (M) domains
are conserved to a lesser extent and are characterized by
a higher content of charged amino acid residues. The
N-terminal (N) domains are highly variable even in
close species, which does not preclude similarity of
their secondary structures (see , review). In yeast,
the N domain is responsible for prion transformation of
Sup35 (eRF3). Mammals have two homologous eRF3
proteins, eRF3a (GSPT1) and eRF3b (GSPT2) [16, 17].
The amino acid sequences of C domains of the mouse
factors (mGSPT1 and mGSPT2) have
95% identity. The main differences between the two
proteins occur in the N (53% similarity) and, to a lesser
extent, M (61% similarity) domains.
Studies of the function of eRF3 family proteins in
cells have shown that mGSPT2 can function-
ally substitute yeast Sup35, whereas human (hGSPT1),
(XSup35), and mouse (mGSPT1) eRF3
cannot. In a two-hybrid system, mGSPT2 interacts with
yeast eRF1 far more efﬁciently than mGSPT1 does .
In this work, we demonstrated that deletion of the N
domain enables hGSPT1, XSup35, and mGSPT1 to
function in yeast cells.
MATERIALS AND METHODS
Strains, media, and plasmids.
We used the following
strains from the Peterhoff genetic collection: 2-33G-
), and 11V-D780 (
). Cells were
grown in the YAPD medium or a synthetic medium sup-
plemented with YNB and necessary metabolites .
Transformants were selected on synthetic media lack-
ing leucine or, when cotransformed with two plasmid,
both leucine and uracil. Elimination of plasmids
Conservation of the MC Domains
in Eukaryotic Release Factor eRF3
G. A. Zhouravleva
, O. M. Zemlyanko
, C. Le Goff
, A. V. Petrova
, and S. G. Inge-Vechtomov
Department of Genetics and Breeding, St. Petersburg University, St. Petersburg, 199034 Russia;
fax: (812)328-05-41; e-mail: firstname.lastname@example.org
St. Petersburg Branch, Vavivol Institute of General Genetics, Russian Academy of Sciences,
St. Petersburg, 199034 Russia
CNRS UMR 6061 Génétique et Dévélopment, Université de Rennes 1, IFR140, 35043 Rennes Cedex, France
Received March 20, 2006
—Eukaryotic translation termination employs two protein factors, eRF1 and eRF3. Proteins of the
eRF3 family each consist of three domains. The N and M domains vary in different species, while the C
domains are highly homologous. The MC domains of
eRF3a (mGSPT1) and eRF3b (mGSPT2) were found to compensate for the
temperature-sensitive mutation and lethal disruption of the
gene in yeast
At the same time, strains containing the MC domains of the eRF3 proteins from different species
differed in growth rate and the efﬁciency of translation termination.