1022-7954/05/4109- © 2005 Pleiades Publishing, Inc.
Russian Journal of Genetics, Vol. 41, No. 9, 2005, pp. 957–967. Translated from Genetika, Vol. 41, No. 9, 2005, pp. 1170–1182.
Original Russian Text Copyright © 2005 by Odintsova, Yurina.
Mitochondria, cellular organelles responsible for
respiration, use electron transport coupled with oxida-
tive phosphorylation to generate ATP. Although mito-
chondria play a key role in energy transduction, they
also participate in other important processes, such as
ion homeostasis and apoptosis. Mitochondria are ubiq-
uitous in eukaryotes with very few exceptions. Some
“amitochondriate” eukaryotes contain derived mito-
chondria (e.g., hydrogenosomes), which produce ATP
anaerobically. Other amitochondriate species possess
remnant mitochondrial structures of currently unknown
functions . However, for mitochondrial functions not
only the components encoded by the mitochondrial
genome (mitochondrial DNA, mtDNA) are necessary.
Many mitochondrial proteins are nuclear-encoded, and
their transcripts are synthesized in cytosol and trans-
ported to the organelles.
mtDNAs of most eukaryotes are circular super-
coiled molecules. Mitochondrial genomes usually con-
sist of a single “chromosome”; however, multiple circu-
lar molecules have been reported for the chytridio-
nematodes , and the
mesozoan animals .
A complex structural organization of the mitochondrial
genome has been reported for kinetoplastid protists
) . Their mitochondrion contains
a few dozen of gene-containing maxicircles and several
thousands minicircles encoding guide RNAs involved
in mRNA editing . Linear monomeric mtDNA mol-
This article was translated by the authors.
ecules have been described in a few unrelated organ-
isms, such as ciliates (
and related organisms),
), fungi (
), and green algae (
) . These linear molecules have speciﬁc
end-structures, such as covalently closed single-
stranded DNA termini or covalently attached proteins,
in addition, they tend to form telomere-like repeats of
various length . An unusual mitochondrial genome
has been detected in the protist
, it is a complex assemblage of several hundred lin-
ear DNA molecules, which carry at their termini similar
short sequences of about 40 bp (
) in inverted orien-
tation followed internally by an ~100-bp repeat (
at one end and a different ~65-bp repeat (
) at the
other end [7, 8].
mtDNA structure differs essentially not only
between eukaryotic kingdoms, but also within each
kingdom (Animalia, Plantae, Fungi, and Protista) as
well. The size of mtDNA varies more than 150-fold:
from 14.3 kb in the nematode
to 2400 kb
in the melon
. Among the completely
sequenced genomes, the smallest genome (6 kb) was
found in apicomplexan protists (
largest (490 kb) genome, which is ~80 times larger than
, was detected in the angiosperm
A large 366.924-kb mitochondrial
genome was described for a ﬂowering plant
; it constitutes about 1/3 of the genome
size of the mitochondria-related bacterium
(1111.5 kb) .
Genomics and Evolution of Cellular Organelles*
M. S. Odintsova and N. P. Yurina
Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, 119071 Russia;
Received December 7, 2004
—The structure, functions, and evolution of cellular organelles are reviewed. The mitochondrial
genomes of eukaryotes differ considerably in size and structural organization mainly due to the length variation
in noncoding regions and the presence of introns. The mitochondrial genomes of angiosperms are the largest
and most complicated. Gene content in eukaryotic mitochondrial genomes is similar. They usually encode all
types of rRNA, a complete or partial complement of tRNA, and a limited number of proteins essential for mito-
chondrial functions. In all eukaryotes studied, mitochondrial genomes code for two highly hydrophobic pro-
teins involved in respiration, cytochrome
and subunit 1 of cytochrome oxidase. Genome structure and gene
content in plastids, mainly in higher plant chloroplasts, are highly conserved. Plastid genomes of algae are more
variable in gene composition and contain several unique genes absent in the chloroplast DNA of higher plants.
Plastid genomes encode proteins involved in transcription and translation, as well as proteins of the photosyn-
thetic apparatus. Both types of cellular organelles are supposed to be of endosymbiotic origin. Modern plastids
originate from a cyanobacterial ancestor. Alpha-proteobacteria, especially the most mitochondrion-like rickett-
sia, gave rise to mitochondria. The origin of plastids of higher plants and green algae as a result of primary endo-
symbiosis and that of other algal lineages by secondary endosymbiosis are brieﬂy discussed.