| Type: | Family | Name: | Cell shape determining protein MreB/Mrl |
| Description: | Bacterial cell shape varies greatly between species, and characteristic morphologies are used for identification purposes. In addition to individualcell shape, the way in which groups of cells are arranged is also typical of some bacterial species, especially Gram-positive coccoids. For many years, it was believed that micro-organisms with other thanspheroidal cell shapes maintained morphology by means of their external cell walls. Recently, however, studies of the Gram-positive rod Bacillus subtilishave revealed two related genes that are essential for the integrity of cell morphogenesis []. Termed mreB and mbl, the gene products localise close tothe cell surface, forming filamentous helical structures. Many homologues have been found in diverse bacterial groups, suggesting a common ancestor [].The crystal structure of MreB from Thermotoga maritimahas been resolved using X-ray crystallography []. It consists of 19 beta-strands and 15 alpha-helices, and shows remarkable structural similarity to eukaryotic actin. MreB crystals also contain proto-filaments, with individual proteins assembling into polymers like F-actin, in the same orientation. It is hypothesised therefore, that MreB was the forerunner of actin in early eukaryotes []. | Short Name: | MreB_Mrl |
