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Lawrence I Rothfield

Publications and source records attributed to Lawrence I Rothfield.

2 recordsLinked to original sources

A polymerization-depolymerization model that accurately generates the self-sustained oscillatory system involved in bacterial division site placement.

Determination of the proper site for division in Escherichia coli and other bacteria involves a unique spatial oscillatory system in which membrane-associated structures composed of the MinC, MinD and MinE proteins oscillate rapidly between the two cell poles. In vitro evidence indicates that this involves ordered cycles of assembly and disassembly of MinD polymers. We propose a mathematical model to explain this behavior. Unlike previous attempts, the present approach is based on the expected behavior of polymerization-depolymerization systems and incorporates current knowledge of the biochemical properties of MinD and MinE. Simulations based on the model reproduce all of the known topological and temporal characteristics of the in vivo oscillatory system.

Adenosine Triphosphatases↗

Membrane localization of MinD is mediated by a C-terminal motif that is conserved across eubacteria, archaea, and chloroplasts.

MinD is a widely conserved ATPase that has been demonstrated to play a pivotal role in selection of the division site in eubacteria and chloroplasts. It is a member of the large ParA superfamily of ATPases that are characterized by a deviant Walker-type ATP-binding motif. MinD localizes to the cytoplasmic face of the inner membrane in Escherichia coli, and its association with the inner membrane is a prerequisite for membrane recruitment of the septation inhibitor MinC. However, the mechanism by which MinD associates with the membrane has proved enigmatic; it seems to lack a transmembrane domain and the amino acid sequence is devoid of hydrophobic tracts that might predispose the protein to interaction with lipids. In this study, we show that the extreme C-terminal region of MinD contains a highly conserved 8- to 12-residue sequence motif that is essential for membrane localization of the protein. We provide evidence that this motif forms an amphipathic helix that most likely mediates a direct interaction between MinD and membrane phospholipids. A model is proposed whereby the membrane-targeting motif mediates the rapid cycles of membrane attachment-release-reattachment that are presumed to occur during pole-to-pole oscillation of MinD in E. coli.

Adenosine Triphosphatases↗