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ATP-dependent interactions between Escherichia coli Min proteins and the phospholipid membrane in vitro
Laura L Lackner1, David M Raskin, Piet A J de Boer
1Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106-4960, USA.
Abstract:
Proper placement of the division apparatus in Escherichia coli requires pole-to-pole oscillation of the MinC division inhibitor. MinC dynamics involves a membrane association-dissociation cycle that is driven by the activities of the MinD ATPase and the MinE topological specificity factor, which themselves undergo coupled oscillatory localization cycles. To understand the biochemical mechanisms underlying Min protein dynamics, we studied the interactions of purified Min proteins with phospholipid vesicles and the role of ATP in these interactions. We show that (i) the ATP-bound form of MinD (MinD.ATP) readily associates with phospholipid vesicles in the presence of Mg(2+), whereas the ADP-bound form (MinD.ADP) does not; (ii) MinD.ATP binds membrane in a self-enhancing fashion; (iii) both MinC and MinE can be recruited to MinD.ATP-decorated vesicles; (iv) MinE stimulates dissociation of MinD.ATP from the membrane in a process requiring hydrolysis of the nucleotide; and (v) MinE stimulates dissociation of MinC from MinD.ATP-membrane complexes, even when ATP hydrolysis is blocked. The results support and extend recent work by Z. Hu et al. (Z. Hu, E. P. Gogol, and J. Lutkenhaus, Proc. Natl. Acad. Sci. USA 99:6761-6766, 2002) and support models of protein oscillation wherein MinE induces Min protein dynamics by stimulating the conversion of the membrane-bound form of MinD (MinD.ATP) to the cytoplasmic form (MinD.ADP). The results also indicate that MinE-stimulated dissociation of MinC from the MinC-MinD.ATP-membrane complex can, and may, occur prior to hydrolysis of the nucleotide.
Insights
MinD protein oscillation in Escherichia coli requires ATP binding for membrane association. MinE protein triggers MinD dissociation from the membrane, influencing cell division dynamics.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Accurate cell division in Escherichia coli depends on the pole-to-pole oscillation of the MinC protein.
- MinC protein dynamics are regulated by the MinD ATPase and MinE protein, which exhibit coupled oscillatory localization.
Purpose of the Study:
- To elucidate the biochemical mechanisms governing Min protein dynamics.
- To investigate the interactions between purified Min proteins and phospholipid vesicles, focusing on the role of ATP.
Main Methods:
- Studied interactions of purified MinD, MinC, and MinE proteins with phospholipid vesicles in the presence of Mg(2+).
- Investigated the influence of ATP binding and hydrolysis on Min protein-membrane interactions.
Main Results:
- MinD.ATP readily associates with phospholipid vesicles, while MinD.ADP does not; MinD.ATP binding is self-enhancing.
- MinC and MinE proteins are recruited to MinD.ATP-decorated vesicles.
- MinE stimulates MinD.ATP dissociation from the membrane via nucleotide hydrolysis and promotes MinC dissociation, even without hydrolysis.
Conclusions:
- MinE protein is crucial in inducing Min protein dynamics by promoting the conversion of membrane-bound MinD.ATP to cytoplasmic MinD.ADP.
- MinE-stimulated MinC dissociation can precede ATP hydrolysis, offering insights into the oscillation mechanism.