FtsZ AND THE DIVISION OF BACTERIAL CELL
I. E. Vishnyakov, S. N. Borchsenius
Institute of Cytology RAS, St. Petersburg, Russia;
e-mail: borch@mail.cytspb.rssi.ru
In this review we have tried to describe proteins and supermolecular structures which take part in the division
of bacterial cell. The principal cell division protein of the most of prokaryotes is FtsZ, a homologue of eukaryotic
tubulin. FtsZ just as tubulin is capable to bind and hydrolyze GTP. The division of bacterial cell begins
with forming of so called divisome. The basis of such divisome is a contractile ring (Z ring); the ring encircles
the cell about midcell. Z ring consists of a bundle of laterally bound protofilaments, which have been formed as
a result of FtsZ polymerization. Z ring is rigidly bounded to cytozolic side of inner membrane with participation
of FtsA, ZipA, FtsW and many other cell division proteins of divisome. The ring directs the process of cytokinesis
transmitting power of constriction to membrane. Primary structures of members of the family of prokaryotic
FtsZs differ from eukaryotic tubulines significantly except the region, where the site of GTP binding is placed.
There is high degree of homology between structures of these proteins in the region. FtsZ is one of the most conservative
proteins in prokaryotes, but ftsZ genes have not been found in completely sequenced genomes of several
species of microorganisms. There are 2 species of mycoplasmas (Ureaplasma parvum and Mycoplasma mobile),
Prostecobacter dejongeii, 10 species of chlamydia and 5 species of archaea among them. So these organisms
divide without FtsZ. There are many open reading frames which encode proteins with unknown functions
in genomes of U. parvum and M. mobile. The comparison of primary structures of these hypothetical proteins
with structures of cell division proteins did not allow researchers to find similar proteins among them. We suppose
that the process of cell division of these organisms should recruit proteins with function similar to FtsZ and
having homologous with FtsZ or other cell division proteins spatial structures.
Key words: FtsZ, division of bacterial cells, mycoplasmas
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