Mutations in the lactose operon caused by bacteriophage Mu

Daniell, Ellen; Roberts, R. C.; Abelson, John

doi:10.1016/0022-2836(72)90019-8

Cited by 103 publications

(46 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…DNA synthesis in five Hfr strains of Escherichia coli K-12 (3,9,10). Mu can also promote the integration of plasmids and direct the transposition of chromosomal markers (11-13).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Integration of bacteriophage Mu at host chromosomal replication forks during lytic development.

Fitts¹,

Taylor²

1980

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

The target site for bacteriophage Mu integration in a lytic cycle of infection was investigated. DNA synthesis in five Hfr strains of Escherichia coli K-12 (3,9,10). Mu can also promote the integration of plasmids and direct the transposition of chromosomal markers (11-13). As is the case with some insertion elements and transposons, Mu prophages in stable lysogens are flanked by a direct repeat of five base pairs of host DNA (14,15). No form of Mu that is free of host DNA has yet been observed.One possible explanation for the ability of this phage to integrate randomly utilizes host chromosomal replication forks as target sites for Mu insertion. In a population of cells replicating asynchronously, the chromosomal replication forks must be distributed over all parts of the bacterial genome; integration of Mu at host replication forks would therefore result in an apparent lack of site specificity for insertion. Integration at host replication forks has been associated with Mu insertion events leading to the formation of stable lysogens (16,17).In this study we asked if the integration events that occur in a lytic cycle of infection involve host chromosomal replication forks. We constructed a system consisting of five Escherichia coli K-12 Fig. 1. Nonsuppressing (Su-) derivatives of the Hfr stocks were isolated by using the procedure of Templin et al. (22). The his-4 allele from strain AB1157 (23) was introduced into each Hfr strain by phage P1 transduction. Strain AT3757 was constructed by phage P1 cotransduction of the pdxAl::Mu -and ara + alleles from AT796 into a spontaneous arabinose-negative mutant of strain AT3753.Bacteriophages. Mucts62SamlO04 was obtained by heat induction of strain MH1671. Mucts62AamlO93 and Mucts62Bam7234 were obtained by heat induction of strains MH219 and MH2808, respectively. A phage strains JC1929 (XN7N53cI26) and JC1930 (h80iXN7N53cI26), used for the construction of Su-strains, were the gift of A. J. Clark.Media. Bacteria were cultured in L broth or in M9 minimal medium (24). Dilutions and washings were done in 0.85% NaCI, except where otherwise noted. Agar plates contained 1% agar (Difco) in L broth plus 5 mM MgSO4 and nalidixic acid (Sigma) at 30 ,ug/ml; agar overlays contained 0.3% agar in L broth plus nalidixic acid at 15 ,ug/ml. Amino Acid Starvation and Nalidixic Acid Treatment.Overnight cultures of Hfr strains in M9 minimal medium supplemented with histidine at 40 ug/ml were diluted 1:100 in 40 ml of the same medium and grown at 37°C for 2 hr with vigorous shaking. After this period of incubation, the cells were collected by filtration (Amicon, 0.45 ,m), washed, resuspended in 40 ml of M9 without histidine, and incubated at 37°C for 200 min to allow existing rounds of replication to terminate (25)(26)(27). We have previously determined by thymidine incorporation assays that DNA synthesis ceases in these his-4 strains after 180 min of starvation (data not shown). Starved cells were collected by filtration and resuspended in 10 ml of L broth Abbreviations: cfu, ...

show abstract

“…DNA synthesis in five Hfr strains of Escherichia coli K-12 (3,9,10). Mu can also promote the integration of plasmids and direct the transposition of chromosomal markers (11-13).…”

mentioning

confidence: 99%

“…The temperate bacteriophage Mu is able to integrate into the DNA of its host at apparently random sites during lysogenization and lytic development (1)(2)(3)(4). Insertions may be precise or may result in deletion of host sequences at the site of integration (5,6).…”

mentioning

confidence: 99%

Integration of bacteriophage Mu at host chromosomal replication forks during lytic development.

Fitts¹,

Taylor²

1980

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…The temperate bacteriophage Mu is characterized by the highly promiscuous integration of its DNA into the genome of its host bacterium Escherichia coli (1)(2)(3). The prophage Mu DNA can be excised precisely from the different integration sites, and as a result wild-type function of the gene into which Mu was inserted can be restored (4).…”

mentioning

confidence: 99%

Influence of insertions on packaging of host sequences covalently linked to bacteriophage Mu DNA.

Bukhari¹,

Taylor²

1975

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Insertions in bacteriophage Mu DNA have been identified. These insertions are responsible for at least seven X mutations, all of which eliminate essential Mu functions. The insertions are about 800 base pairs long and are located to the left of the cleavage site of restriction endonuclease EcoRI, near the immunity end of Mu DNA. We have found that such-insertions cause a reduction in the length of nonhomologous terminal sequences which are seen as split ends in denatured and renatured Mu DNA molecules. These heterogeneous sequences apparently arise from packaging of host DNA from maturation precursors in which Mu and host DNA are covalently linked. We infer that a single Mu genome length is too short to be cut during morphogenesis, and thus some host DNA is packaged into mature virions. Since the insertions increase the length of Mu DNA, they decrease the amount of host DNA needed for packaging.The temperate bacteriophage Mu is characterized by the highly promiscuous integration of its DNA into the genome of its host bacterium Escherichia coli (1-3). The prophage Mu DNA can be excised precisely from the different integration sites, and as a result wild-type function of the gene into which Mu was inserted can be restored (4). This reversal of Mu integration can be seen if the prophages contain the X mutations, which block the lethal and essential phage functions.Mu X mutants revert to wild type at a frequency of about 10-8. However, no X amber mutants have been found. Thus, we proposed that the X mutations are insertions (4). We have investigated the nature of the X mutations by agarose-gel electrophoresis of Mu DNA fragments produced by specific endonucleases, and by electron microscopic examination of Mu DNA heteroduplexes. These studies have shown that the X mutations are insertions near the immunity (c) end of Mu DNA. In one X mutant, the insertion is demonstrated to be of about 720 base pairs, located 4 kilobases (kb) away from the c end.The isolation of insertions in Mu DNA has allowed us to analyze further some aspects of Mu DNA structure. Mu DNA, a double-stranded linear duplex of about 37 kb (5), has some interesting features. When it is denatured and reannealed, two types of homoduplex molecules are obtained (Fig. 1). All the molecules show single-stranded tails or split ends, measuring about 4% of the molecular length. The split ends, which apparently represent sequences picked up randomly from the, E. coli chromosome, are always found at the S gene end, called here the SE end, of Mu DNA (6-8). Some molecules show another nonrenaturable region, termed the G bubble, near the SE end (9). Recently, we observed that the c end of Mu DNA is also not fixed, and probably varies in length by about 100 base pairs (10, 11).Abbreviation: kb, kilobase. t To whom correspondence should be directed.One plausible model for the origin of the heterogeneity of the SE end is that Mu DNA is packaged into phage heads from maturation precursors which contain both Mu DNA and host sequences. This hypothesis implies that...

show abstract

“…The temperate bacteriophage Mu can integrate at random into the chromosome of its host Escherichia coli K 1 2 (Taylor, 1963;Bukhari & Zipser, 1972;Daniell, Roberts & Abelson, I 972). Insertion into a gene can make it inactive and give rise to a mutation (Taylor, 1963).…”

Section: Introductionmentioning

confidence: 99%

Introduction of Bacteriophage Mu into Pseudomonas solanacearum and Rhizobium meliloti using the R Factor RP4

Boucher¹,

Bergeron²,

Bertalmio³

et al. 1977

Journal of General Microbiology

View full text Add to dashboard Cite

Mutations in the lactose operon caused by bacteriophage Mu

Cited by 103 publications

References 17 publications

Integration of bacteriophage Mu at host chromosomal replication forks during lytic development.

Integration of bacteriophage Mu at host chromosomal replication forks during lytic development.

Influence of insertions on packaging of host sequences covalently linked to bacteriophage Mu DNA.

Introduction of Bacteriophage Mu into Pseudomonas solanacearum and Rhizobium meliloti using the R Factor RP4

Contact Info

Product

Resources

About