Mutual effects of MinD–membrane interaction: I. Changes in the membrane properties induced by MinD binding

Abstract

Summary In E. coli and other bacteria, MinD, along with MinE and MinC, rapidly oscillates from one pole of the cell to the other controlling the correct placement of the division septum. MinD binds to the membrane through its amphipathic C-terminal α-helix. This binding, promoted by ATP-induced dimerization, may be further enhanced by a consequent attraction of acidic phospholipids and formation of a stable proteolipid domain. In the context of this hypothesis we studied changes in dynamics of a model membrane caused by MinD binding using membrane-embedded fluorescent probes as reporters. A remarkable increase in membrane viscosity and order upon MinD binding to acidic phospholipids was evident from the pyrene and DPH fluorescence changes. This viscosity increase is cooperative with regards to the concentration of MinD-ATP, but not of the ADP form, indicative of dimerization. Moreover, similar changes in the membrane dynamics were demonstrated in the native inverted cytoplasmic membranes of E. coli, with a different depth effect. The mobility of pyrene-labeled phosphatidylglycerol indicated formation of acidic phospholipid-enriched domains in a mixed acidic-zwitterionic membrane at specific MinD/phospholipid ratios. A comparison between MinD from E. coli and N. gonorrhea is also presented.

Multiple modes of interconverting dynamic pattern formation by bacterial cell division proteins

“…We propose that the mechanical stress in the membrane structure caused by binding of the initiation or dissociation centers affects the affinity of the membrane in the neighborhood of the complex to additional protein binding. Distortion of the membrane structure by MinD binding has been evidenced by the previous observation that unilamellar vesicles are converted to thin tubes by high-density binding of MinD (32), as well as recent fluorescence anisotropy and calorimetry studies of MinD interactions with lipid membranes (37,38). The above "membrane stress" hypothesis also explains additional aspects of our results as discussed below.…”

Mapping out Min protein patterns in fully confined fluidic chambers

“…Biochemical assays have shown intricate effects of the Min system on the membrane organization in the in vivo context. For example, MinD increased the order of the lipids and decreased their mobility in inverted inner E. coli membranes that contained integral proteins more than it does in synthetic vesicles that are purely lipidic (Mazor et al, 2008). Similarly, the Min system affects the association of inner-membrane peripheral proteins and interacts with some of them directly (Lee et al, 2016).…”

Cardiolipin membrane domains in prokaryotes and eukaryotes

“…In vitro experiments demonstrate that MinD binding to model membranes in which anionic and zwitterionic phospholipids are either uniformly mixed or segregated into domains is enhanced by segregation of anionic phospholipids to fluid domains in a gel-phase environment. Moreover, MinD stabilizes such domains [46, 47]. Taking into account the permanent nature of PG-spirals in the cell, it is not necessary in this case to postulate appearance of mid-cell anionic lipid domains immediately before initiation of DNA replication.…”