Molecular and structural mechanisms of cell
division site recognition in Bacillus
subtilis
Barák I.1, K. Muchová1, N. Pavlendová1, P. Florek1,
N. Pavlendová1, J. Jamroškovič1, Anthony J. Wilkinson2,
Ľ. Vávrová1 and
S. Rešetárová1
1Institute of Molecular Biology, Slovak Academy of Sciences, Bratislava
2Department of Chemistry, University of York, York, UK
Bacillus subtilis
is an internationally-recognised model organism, whose physiology, biochemistry
and genetics has been studied for many years. Our research is oriented toward
studying the proteins involved in basic processes in Bacillus subtilis as cell
division, sporulation and programmed cell death.
Probably the most
controversial question regarding cell division of rod-shaped bacteria concerns
the mechanism that ensures correct placement of the division septum. At least
two distinct mechanisms contribute to placement of the division machinery: the
Min system and nucleoid occlusion. The
fluid mosaic model of membrane structure has been revised in recent years as it
has become evident that domains of different lipid composition are present in
eukaryotic and prokaryotic cells. Using membrane binding fluorescent dyes, we
demonstrate the presence of lipid spirals extending along the long-axis of
cells of the rod-shaped bacterium B. subtilis. These spiral structures are
absent from cells in which the synthesis of
phosphatidylglycerol is disrupted suggesting an enrichment in anionic
phospholipids. Green fluorescent protein fusions of the cell division protein MinD
from B. subtilis also form spiral structures and these were shown by
fluorescence resonance energy transfer (FRET) to be coincident with the lipid
spirals. These data indicate a higher level of membrane lipid organization than
previously observed and a primary role for lipid spirals in determining the
site of cell division in bacterial cells. Little is known however
of the origin of these spiral structures. In our current work we have focused
on analyzing these lipid structures in correlation with other previously
observed helical structures in the cell membrane or its close proximity.
Acknowledgements
This work was supported by the grant
APVT-51-027804, No. ESF-EC-0106, LPP-0218-06 and VEGA grant 2/7007/27 from the
Slovak Academy of Sciences and The Wellcome Trust Grant 082829/Z/07/Z.