13
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: not found
      • Article: not found

      An actin-like gene can determine cell polarity in bacteria

      , ,

      Proceedings of the National Academy of Sciences

      Proceedings of the National Academy of Sciences

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Achieving proper polarity is essential for cellular function. In bacteria, cell polarity has been observed by using both morphological and molecular markers; however, no general regulators of bacterial cell polarity have been identified. Here we investigate the effect on cell polarity of two cytoskeletal elements previously implicated in cell shape determination. We find that the actin-like MreB protein mediates global cell polarity in Caulobacter crescentus, although the intermediate filament-like CreS protein influences cell shape without affecting cell polarity. MreB is organized in an axial spiral that is dynamically rearranged during the cell cycle, and MreB dynamics may be critical for the determination of cell polarity. By examining depletion and overexpression strains, we demonstrate that MreB is required both for the polar localization of the chromosomal origin sequence and the dynamic localization of regulatory proteins to the correct cell pole. We propose that the molecular polarity inherent in an actin-like filament is translated into a mechanism for directing global cell polarity.

          Related collections

          Most cited references 36

          • Record: found
          • Abstract: not found
          • Article: not found

          Origins of cell polarity.

            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Prokaryotic origin of the actin cytoskeleton.

            It was thought until recently that bacteria lack the actin or tubulin filament networks that organize eukaryotic cytoplasm. However, we show here that the bacterial MreB protein assembles into filaments with a subunit repeat similar to that of F-actin-the physiological polymer of eukaryotic actin. By elucidating the MreB crystal structure we demonstrate that MreB and actin are very similar in three dimensions. Moreover, the crystals contain protofilaments, allowing visualization of actin-like strands at atomic resolution. The structure of the MreB protofilament is in remarkably good agreement with the model for F-actin, showing that the proteins assemble in identical orientations. The actin-like properties of MreB explain the finding that MreB forms large fibrous spirals under the cell membrane of rod-shaped cells, where they are involved in cell-shape determination. Thus, prokaryotes are now known to possess homologues both of tubulin, namely FtsZ, and of actin.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Crystal structure of the bacterial cell-division protein FtsZ.

               A. J. Lowe,  L Amos (1998)
              Bacterial cell division ends with septation, the constriction of the cell wall and cell membranes that leads to the formation of two daughter cells. During septation, FtsZ, a protein of relative molecular mass 40,000 which is ubiquitous in eubacteria and is also found in archaea and chloroplasts, localizes early at the division site to form a ring-shaped septum. This septum is required for the mechanochemical process of membrane constriction. FtsZ is a GTPase with weak sequence homology to tubulins. The nature of FtsZ polymers in vivo is unknown, but FtsZ can form tubules, sheets and minirings in vitro. Here we report the crystal structure at 2.8 A resolution of recombinant FtsZ from the hyperthermophilic methanogen Methanococcus jannaschii. FtsZ has two domains, one of which is a GTPase domain with a fold related to one found in the proteins p21ras and elongation factor EF-Tu. The carboxy-terminal domain, whose function is unknown, is a four-stranded beta-sheet tilted by 90 degrees against the beta-sheet of the GTPase domain. The two domains are arranged around a central helix. GDP binding is different from that typically found in GTPases and involves four phosphate-binding loops and a sugar-binding loop in the first domain, with guanine being recognized by residues in the central connecting helix. The three-dimensional structure of FtsZ is similar to the structure of alpha- and beta-tubulin.
                Bookmark

                Author and article information

                Journal
                Proceedings of the National Academy of Sciences
                Proceedings of the National Academy of Sciences
                Proceedings of the National Academy of Sciences
                0027-8424
                1091-6490
                June 08 2004
                June 08 2004
                May 24 2004
                June 08 2004
                : 101
                : 23
                : 8643-8648
                Article
                10.1073/pnas.0402638101
                423248
                15159537
                © 2004
                Product

                Comments

                Comment on this article