Attachment of Chromosomes to Membranes in Bacteria and Animal Cells
It has been proposed that in bacteria the attachment of DNA to the cytoplasmic membrane serves to ensure proper chromosome segregation (Jacob et al., 1963). The lack of a mitotic apparatus has made this an appealing suggestion and the subject of considerable study. The methodology available--electron microscopy and cell fractionation--is not sufficiently developed to allow definitive conclusions about the nature and physiological importance of the connection between the two structures. Nevertheless, there are indications that DNA-membrane complexes may play a role in other functions than chromosome segregation, namely, replication, transcription, or the maintenance of the physical configuration of the DNA. We have recently reviewed these subjects in some detail (Leibowitz and Schaechter, 1975). In addition, the suggestion has been made that changes in the membrane provide the signal for initiation of DNA replication (Marvin, 1967; Helmstetter, 1974). The cell membrane appears to be directly involved in the replication and maturation of bacteriophages and other viruses. In these systems, the physiological role of the membrane is even less understood (for a review, see Siegel and Schaechter, 1973).
KeywordsBacillus Subtilis Nuclear Membrane Cytoplasmic Membrane Chromosome Segregation Replication Origin
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