The definitive version is available at www.blackwell-synergy.com
http://dx.doi.org/10.1111/j.1574-6976.2007.00098.x
For growth and division of rod-shaped bacteria, the cylindrical part of the sacculus has to be elongated and two new cell poles have to be synthesized. The elongation is performed by a protein complex, the elongase that inserts disaccharidepentapeptide units at a limited number of discrete sites while using the cytoskeletal MreB helix as a tracking device. Upon initiation of cell division by positioning of the cytoskeletal Z-ring at mid cell, a switch from dispersed to concentrated local peptidoglycan-synthesis occurs. From this point on, peptidoglycan synthesis is for a large part redirected from elongating activity to synthesis of new cell poles by the divisome. The divisome might be envisioned as an extended elongase because apart from its basic peptidoglycan synthesizing activity, specific functions have to be added. These are conversion from a cylinder to a sphere, invagination of the outer membrane and addition of hydrolases that allow separation of the daughter cells. The elongase and the divisome are dynamic hyperstructures that probably share part of their proteins. Although this multifunctionality and flexibility form a barrier to the functional elucidation of its individual subunits, it helps the cells to survive a variety of emergency situations and to proliferate securely.
This work was supported in part by the European commission within the ‘EUR-INTAFAR’ LSHM-CT-2004-512138, and ‘COBRA’ LSHM-CT-2003-503335 networks and by a Vernieuwingsimpuls grant 016.001.024 of the
Netherlands Organization for Scientific Research (NWO)to T.d.B., by the Belgian State, Prime Minister’s Office, Science Policy programming (IAP no. P6/19), the Actions de Recherche Concert´ees (grant no. 03/08-297), the Fond de la Recherche Fondamentale Collective (contract no.
2.4543.05) to M.N., and BFU2006-04574 from Ministerio de Educación y Ciencia, Spain, to J.A.A. and an institutional grant from Fundación Ramón Areces.
Peer reviewed