Mesosomes in Escherichia coli

Abstract

When Escherichia coli was grown in a synthetic medium and fixed with osmium, sections of the cells revealed clearly defined mesosomes. These mesosomes appeared to develop, in dividing cells, as coiled infoldings of the cytoplasmic membrane. Mature mesosomes formed a link between the cytoplasmic membrane and the nucleus of the cell. The arrangement of the mesosomes in dividing cells led to the hypothesis that division of the nucleus in these cells is accomplished by two separate polar mesosomes. One mesosome is derived from the parent cell and is present at one pole of the daughter cell. The other is freshly synthesized at or near the newly forming pole of the daughter cell. While the old mesosome remains attached to the chromosome received from the parent cell, the newly synthesized mesosome becomes attached to and initiates replication of the new chromosome. As the cell grows and elongates, the two mesosomes, attached to their respective chromosomes move apart, thus effecting nuclear division.

Ultrastructural Properties of the Extra Membranes of Escherichia coli O111a as Revealed by Freeze-Fracturing and Negative-Staining Techniques

“…It should be mentioned that the invaginations of the plasma membrane which joins the extra membranes in E. coli Ollla are generally dissimilar from the mesosomal structures described for gram-positive bacteria. In general, the invaginations in E. coli Ollla seem to be direct extensions of the plasma membrane and do not appear to form a pocket into which a "string of beads" structure typical of grampositive mesosomes is coiled (21,23) although a sac-like invagination is seen in Fig. 5A.…”

“…In general, extensive internal membranes have not been considered characteristic cell components of gram-negative bacteria (6) although several workers have reported the formation of intracellular membranes by certain strains of Escherichia coli when grown in Mg2+deficient media (6, 7), exposed to elevated temperatures (23), or infected by bacteriophage (20). In some cases, these internal membranes have been interpreted to be mesosomes which require special conditions of fixation and embedding so that they might be seen in the electron microscope (21). It was shown previously that E. coli Ollla is a thermosensitive strain which, when grown at 40 C, accumulates large amounts of internal membranes (26,27; R. A. Weigand and J. W. Greenawalt, Fed.…”

Mesosome Structure in Chromobacterium violaceum

“…The occurrence of intracytoplasmic membranes in non-photosynthetic gram-negative bacteria is amply documented (5,7,13,16,18,21,27,32); however, reports of membranes in gram-negative bacteria conforming to the definition of mesosomes in gram-positive bacteria (9,20) have been few (6,17). In this report we have described membranous structures in C. violaceum that conform to the only established criteria for the definition of mesosomes, namely morphology and physical reaction to environmental conditions, in an organism with the ultrastructural anatomy and lipid composition characteristic of gram-negative bacteria (19).…”

“…The term mesosome is frequently used to describe membranous structures in gram-negative bacteria (5,13,18). These structures, however, have not always met criteria accepted for gram-positive mesosomes.…”

Hochgeordnete Feinstruktur des Chromosoms in Escherichia coli

“…Den ausgedehnten Membrankorpern grampositiver Bakterien ist eine Beteiligung auch an Replikation und Segregation der DNS-Strukturen zugesprochen worden (JACOB et al, 1966;KAKEFUDA et al, 1967;RYTER u. JACOB, 1964). Bei den gramnegativen E. coli-Bakterien wurden nur kleine und einfache Membrankorper in bestimmten Stammen beschrieben (PONTEFRACT et al, 1969;RYTER, 1968 CALLAN, 1962;TAYLOR, 1963 (GIESBRECHT, 1961 ;KELLENBERGER, 1962;ROBBINS, 1961 ;SCHREIL, 1961). Die Fixierung denaturiert zunachst die ,,semipermeable" Cytoplasmamembran, und so bleibt die DNS dem Aui3enmedium zumindest bis zu ihrer Stabilisierung ungeschutzt ausgesetzt.…”