The Actin-Like Cytoskeleton
from: Bacillus: Cellular and Molecular Biology (Edited by: Peter Graumann). Caister Academic Press, U.K. (2007)
Prokaryotic cells possess filamentous proteins, analogous to eukaryotic cytoskeletal proteins, that play a key role in the spatial organization of essential cellular processes. The bacterial homologues of actin (MreB, ParM and MamK proteins) are involved in cell shape determination, DNA segregation, cell polarity, and other functions that require the targeting and accurate positioning of proteins and molecular complexes in the cell. In Bacillus subtilis, MreB homologues (MreB, Mbl and MreBH) assemble into helical structures that control morphogenesis by actively directing the growth of the cylindrical cell wall (elongation). The ultimate morphology of the cell is believed to depend on a dynamic interplay between the intracellular MreB cytoskeleton and the extracellular proteins that carry out cell wall biosynthesis and degradation, probably linked through the MreCD and/or other membrane proteins. The general properties of the MreB proteins, relative to eukaryotic actin and to other prokaryotic homologues of actin, and the known functions of the MreB cytoskeleton in B. subtilis and other bacteria, will be discussed in this chapter read more ...