Papers by Lawrence Rothfield
Journal of Molecular Biology, 1970
Journal of Molecular Biology, 1970
Annual Review of Genetics, 1999
Bacteria usually divide by building a central septum across the middle of the cell. This review f... more Bacteria usually divide by building a central septum across the middle of the cell. This review focuses on recent results indicating that the tubulin-like FtsZ protein plays a central role in cytokinesis as a major component of a contractile cytoskeleton. Assembly of this cytoskeletal element abutting the membrane is a key point for regulation. The characterization of FtsZ homologues in Mycoplasmas, Archaea, and chloroplasts implies that the constriction mechanism is conserved and that FtsZ can constrict in the absence of peptidoglycan synthesis. In most Eubacteria, the internal cytoskeleton must also regulate synthesis of septal peptidoglycan. The Escherichia coli septum-specific penicillin-binding protein 3 (PBP3) forms a complex with other enzymes involved in murein metabolism, suggesting a centrally located transmembrane complex capable of splicing multiple new strands of peptidoglycan into the cell wall. Important questions remain about the spatial and temporal control of bacterial division.
Journal of Membrane Biology, 1972
Guanidinium thiocyanate was shown to be effective in solubilizing over 80% of the protein of theE... more Guanidinium thiocyanate was shown to be effective in solubilizing over 80% of the protein of theE. coli cell envelope. Fractionation of the solubilized membrane polypeptides by ion exchange chromatography was achieved following removal of the guanidinium thiocyanate by dialysis against 6m urea.
Proceedings of The National Academy of Sciences, 2003
The MinCDE proteins of Escherichia coli are required for proper placement of the division septum ... more The MinCDE proteins of Escherichia coli are required for proper placement of the division septum at midcell. The site selection process requires the rapid oscillatory redistribution of the proteins from pole to pole. We report that the three Min proteins are organized into extended membrane-associated coiled structures that wind around the cell between the two poles. The pole-to-pole oscillation of the proteins reflects oscillatory changes in their distribution within the coiled structure. We also report that the E. coli MreB protein, which is required for maintaining the rod shape of the cell, also forms extended coiled structures, which are similar to the MreB structures that have previously been reported in Bacillus subtilis. The MreB and MinCDE coiled arrays do not appear identical. The results suggest that at least two functionally distinct cytoskeletal-like elements are present in E. coli and that structures of this type can undergo dynamic changes that play important roles in division site placement and possibly other aspects of the life of the cell.
Proceedings of The National Academy of Sciences, 2007
RNaseE is the main component of the RNA degradosome of Escherichia coli, which plays an essential... more RNaseE is the main component of the RNA degradosome of Escherichia coli, which plays an essential role in RNA processing and decay. Localization studies showed that RNaseE and the other known degradosome components (RNA helicase B, polynucleotide phosphorylase, and enolase) are organized as helical filamentous structures that coil around the length of the cell. These resemble the helical structures formed by the MreB and MinD cytoskeletal proteins. Formation of the RNaseE cytoskeletal-like structure requires an internal domain of the protein that does not include the domains required for any of its known interactions or the minimal domain required for endonuclease activity. We conclude that the constituents of the RNA degradosome are components of the E. coli cytoskeleton, either assembled as a primary cytoskeletal structure or secondarily associated with another underlying cytoskeletal element. This suggests a previously unrecognized role for the bacterial cytoskeleton, providing a mechanism to compartmentalize proteins that act on cytoplasmic components, as exemplified by the RNA processing and degradative activities of the degradosome, to regulate their access to important cellular substrates.
Molecular Microbiology, 2005
Establishment of an axis of cell polarity and differentiation of the cell poles are fundamental a... more Establishment of an axis of cell polarity and differentiation of the cell poles are fundamental aspects of cellular development in many organisms. We compared the effects of two bacterial cytoskeletal-like systems, the MreB and MinCDE systems, on these processes in Escherichia coli. We report that the Min proteins are capable of establishing an axis of oscillation that is the initial step in establishment of polarity in spherical cells, in a process that is independent of the MreB cytoskeleton. In contrast, the MreB system is required for establishment of the rod shape of the cell and for polar targeting of other polar constituents, such as the Shigella virulence factor IcsA and the aspartate chemoreceptor Tar, in a process that is independent of the Min system. Thus, the two bacterial cytoskeletal-like systems act independently on different aspects of cell polarization.
Nature Reviews Microbiology, 2005
| The site of cell division in bacterial cells is placed with high fidelity at a designated posit... more | The site of cell division in bacterial cells is placed with high fidelity at a designated position, usually the midpoint of the cell. In normal cell division in Escherichia coli this is accomplished by the action of the Min proteins, which maintain a high concentration of a septation inhibitor near the ends of the cell, and a low concentration at midcell. This leaves the midcell site as the only available location for formation of the division septum. In other species, such as Bacillus subtilis, this general paradigm is maintained, although some of the proteins differ and the mechanisms used to localize the proteins vary. A second mechanism of negative regulation, the nucleoid-occlusion system, prevents septa forming over nucleoids. This system functions in Gram-negative and Gram-positive bacteria, and is especially important in cells that lack the Min system or in cells in which nucleoid replication or segregation are defective. Here, we review the latest findings on these two systems.
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Papers by Lawrence Rothfield