Inhibition of bacterial segregation by early functions of phage Mu and association of replication protein B with the inner cell membrane

Abstract

Infection of Mu-sensitive bacteria with a recombinant lambda phage that carries the EcoRI.C fragment from the immunity end of wild type Mu DNA causes filamentous growth. Transmission electron microscopy revealed that the cell-division cycle was inhibited at, or prior to, the initiation of septation. The filamentation does not occur after infection of Mu-immune bacteria or after infection with a phage carrying the same EcoRI.C fragment, but with an IS1 insertion in gene B of Mu, showing that either gpB and/or some non-essential functions (e.g. kil) mapping downstream from the insertion are required for the inhibition of cell division. These data and previously published evidence suggest that in the "killing" of E. coli K12 by early Mu functions expressed from the cloned EcoRI.C fragment, two components have to be distinguished: one, a highly efficient elimination of plasmid DNA carrying the early Mu genes, and second, a series of interactions with host functions conducent to an inhibition of cell division. It is suggested that functions normally involved in the SOS reaction participate in the inhibition of cell division by early Mu functions. Infected bacteria synthesize the replication protein B (MR 33000) of Mu, which was found by cell fractionation experiments to be associated with the inner cell membrane. The role of this association for filamentous growth and for the integrative replication of the phage is discussed. The recombinant phage might be useful as a tool for the study of the E. coli cell division cycle.

Overexpression of the Tn5 transposase in Escherichia coli results in filamentation, aberrant nucleoid segregation, and cell death: analysis of E. coli and transposase suppressor mutations

“…High-level expression of the Mu B protein involved in transposon target site selection has been shown to be lethal to E. coli and also leads to filament formation (4). The Mu B protein also fractionates with the inner cell membrane (4). A number of other bacterial IS Tnps also lead to cell killing and filamentation when overexpressed (1).…”

Examination of the Tn5 transposase overproduction phenotype in Escherichia coli and localization of a suppressor of transposase overproduction killing that is an allele of rpoH

“…Interestingly, not only does overproduction of the MuB protein cause the same cell killing phenotype as that of Tn5 Tnp but Boeckh et al (7) have reported that MuB also associates with the inner cell membrane. Thus, we conclude that Tn5 Tnp (and perhaps MuB) overproduction killing is correlated with inner cell membrane association.…”

Role of the Dna/Membrane Complex in Prokaryotic Dna Replication

“…It has long been known that a T4 deoxynucleotide synthetase is involved in supplying immediate DNA precursors to the replisome (12,79,97) and that one of the enzymes in this complex, dCTPase, is also encoded by the oriA region (88). These include the dnaB protein of B. subtilis (46,118), the dnaJ and dnaK proteins of E. coli (144,145,147), the dnaA protein of E. coli (104,105,142), the B protein of phage Mu (8,103) (see below), possibly the P initiation protein of phage A (146), and possibly the trfA initiation protein of plasmid RK2 (62). These include the dnaB protein of B. subtilis (46,118), the dnaJ and dnaK proteins of E. coli (144,145,147), the dnaA protein of E. coli (104,105,142), the B protein of phage Mu (8,103) (see below), possibly the P initiation protein of phage A (146), and possibly the trfA initiation protein of plasmid RK2 (62).…”

“…In addition, the copy number of the minichromosome varied considerably from population to population, which implies that there was an abnormality in control mech anisms, possibly related to incompatibility functions (89). New developments have in volved DNA binding studies with specific membrane proteins or membrane preparations (41, 55,61,66,69,81,120,132,133), striking correlations between defects in the conformation or activity of the DNA/membrane com plex and inhibition of initiation (51,92,130,139), further analysis of the synthetic capabilities of DNA/membrane complexes (6,7,22,24,25,27,62,67,69,143), and identification or recognition of specific genes that may code for membrane proteins involved in DNA replication (8,46,87,88,103,105,118,145,146). Yoshimoto et al (141) found that replicative intermediates of an OriC plasmid associated with the outer membrane of E. coli were free of globular (membrane) proteins, whereas the chromosomal oriC was associated with such components.…”