Compartmentalization of the periplasmic space at division sites in gram-negative bacteria

Abstract

Phase-contrast and serial-section electron microscopy were used to study the patterns of localized plasmolysis that occur when cells of Salmonella typhimurium and Escherichia coli are exposed to hypertonic solutions of sucrose. In dividing cells the nascent septum was flanked by localized regions of periseptal plasmolysis. In randomly growing populations, plasmolysis bays that were not associated with septal ingrowth were clustered at the midpoint of the cell and at 1/4 and 3/4 cell lengths. The localized regions of plasmolysis were limited by continuous zones of adhesion that resembled the periseptal annular adhesion zones described previously in IkyD mutants of S. typhimurium (T. J. MacAlister, B. MacDonald, and L. I. Rothfield, Proc. Natl. Acad. Sci. USA 80:1372-1376, 1983 [wt/vol]). After the cells were kept at room temperature for 3 min, they were fixed by the addition of glutaraldehyde to a final concentration of 2.5%. The suspension was allowed to stand for an additional 60 min at room temperature and centrifuged for 4 min at 14,000 x g, and the pellet was suspended in fresh medium (refractive index, 1.335).

The Bacterial Cytoskeleton

“…The poles of rod-shaped cells differ in several respects from the remainder of the cell body. These differences include the specific polar localization of a number of membrane-associated proteins (90), the presence of polar flagella or pili in certain species (185), the lack of turnover of murein and of externally labeled surface proteins at the cell poles (31,33), the absence of zones of adhesion between the inner membrane and the murein-outer membrane layer at the poles (23,131), and anatomic changes (the bacterial birth scar) at the newly formed cell pole (130). MreB has been implicated in one of these aspects of cell polarity, the localization of specific proteins to one or both cell poles.…”

Plasmolysis bays in Escherichia coli: are they related to development and positioning of division sites?

“…Several proteins have been implicated to be specifically involved in the division process (5), but the positioning mechanism itself has remained elusive. Two opposing models for positioning of division sites have been proposed: in one model, a newborn cell already contains a preexisting division site formed by replication and lateral displacement of an annular envelope structure (2,3,13) and in the other model, the site is generated only after chromosome duplication and nucleoid segregation (9,19,20).In the first model, the growing envelope contains concentric rings of adhesion (so-called periseptal annuli) between the plasma membrane and the cell wall (peptidoglycan layer and outer membrane). The periseptal annulus model assumes that each newborn cell contains a pair of such annuli in its center.…”

Localization of the Outer Membrane Protein OmpA2 in Caulobacter crescentus Depends on the Position of the Gene in the Chromosome

“…To verify that the fusion protein was inserted in the OM, cells grown in highphosphate medium were plasmolyzed and observed with the microscope. It has been reported that under hyperosmotic shock, the inner membrane separates from the cell wall and compacts into plasmolysis bays (59). To validate the plasmolysing conditions, LDG1 cells expressing, under the control of a xylose-inducible promoter, the IM protein TolQ fused to yellow fluorescent protein (YFP) were used.…”