1 research outputs found
Anionic Lipid Binding to the Foreign Protein MGS Provides a Tight Coupling between Phospholipid Synthesis and Protein Overexpression in <i>Escherichia coli</i>
Certain membrane proteins involved
in lipid synthesis can induce
formation of new intracellular membranes in <i>Escherichia coli</i>, i.e., intracellular vesicles. Among those, the foreign monotopic
glycosyltransferase MGS from <i>Acholeplasma laidlawii</i> triggers such massive lipid synthesis when overexpressed. To examine
the mechanism behind the increased lipid synthesis, we investigated
the lipid binding properties of MGS <i>in vivo</i> together
with the correlation between lipid synthesis and MGS overexpression
levels. A good correlation between produced lipid quantities and overexpressed
MGS protein was observed when standard LB medium was supplemented
with four different lipid precursors that have significant roles in
the lipid biosynthesis pathway. Interestingly, this correlation was
highest concerning anionic lipid production and at the same time dependent
on the selective binding of anionic lipid molecules by MGS. A selective
interaction with anionic lipids was also observed <i>in vitro</i> by <sup>31</sup>P NMR binding studies using bicelles prepared with <i>E. coli</i> lipids. The results clearly demonstrate that the
discriminative withdrawal of anionic lipids, especially phosphatidylglycerol,
from the membrane through MGS binding triggers an <i>in vivo</i> signal for cells to create a “feed-forward” stimulation
of lipid synthesis in <i>E. coli</i>. By this mechanism,
cells can produce more membrane surface in order to accommodate excessively
produced MGS molecules, which results in an interdependent cycle of
lipid and MGS protein synthesis