Effect of Rifampin on the Structure and Membrane Attachment of the Nucleoid of Escherichia coli

Abstract

Deoxyribonucleic acid (DNA) of Escherichia coli was found to be attached to the cell membrane at about 20 points. This was determined by fractionation of X-irradiated cells with the M band (magnesium-Sarkosyl crystals) technique. The number of attachment points was computed from the relationship between the amount of DNA in M bands and the number of double-strand breaks introduced by the X-ray treatment. The number of attachment points was decreased fourfold by treatment of cells with rifampin. This effect was apparently due to the action of the drug on ribonucleic acid (RNA) polymerase since the drug did not affect a mutant whose RNA polymerase is resistant to rifampin. This suggests that there may be two classes of attachment points of DNA on the membrane, some of which are removed by rifampin treatment and some which are not. Rifampin treatment also resulted in the uncondensing of isolated nucleoids and in an axial appearance of the nucleoids in ultrathin sections. The results suggest that RNA polymerase plays a role, direct or indirect, in maintaining the structure of the bacterial nucleoid and in some of its attachment to the membrane.

A genetic selection for supercoiling mutants of Escherichia coli reveals proteins implicated in chromosome structure

“…The effect of transcription on domain barrier formation has been tested using the transcriptional inhibitor, rifampicin, but the results were inconclusive. Rifampicin caused chromosomes to decondense upon isolation (Dworsky and Schaechter, 1973;Pettijohn and Hecht, 1974), but did not change the number of domains measured in vivo (Sinden and Pettijohn, 1981).…”

Transcription‐coupled nucleoid architecture in bacteria

“…Rifampicin affects nucleoid condensation (Morgan et al 1967;Dworsky & Schaechter 1973;Kleppe et al 1979;Vos-Scheperkeuter & Witholt 1982;Sun & Margolin 2004;Kruse et al 2006). Many reports have described the indirect attachment of DNA to the plasma membrane via coupled transcription, translation and translocation of membrane proteins (Kleppe et al 1979;Vos-Scheperkeuter & Witholt 1982).…”

“…Biochemical studies showing reduced sedimentation rate of the isolated nucleoid after RNase treatment have suggested that RNA is situated at the boundaries of nucleoid folding in the core region (Worcel & Burgi 1972;Pettijohn & Hecht 1974). EM studies have shown that the nucleoid shrinks in response to rifampicin treatment, suggesting that RNA anchors the nucleoid to the cell membrane (Dworsky & Schaechter 1973;Kleppe et al . 1979;Vos-Scheperkeuter & Witholt 1982).…”

The cell cycle ofEscherichia coliand some of its regulatory systems

“…On the one hand, the search for a membrane growth zone; on the other hand, studies on attachment sites between DNA and the bacterial envelope. Such sites have been demonstrated [4][5][6][7], including complexes involving the region of the replication origin and the inner membrane of E. coli [8,5]. Similar observations have been made for Bacillus subtilis [9][10][11].…”