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PubMed2002

Lysogeny in marine Synechococcus.

Viral infection of bacteria can be lytic, causing destruction of the host cell, or lysogenic, in which the viral genome is instead stably maintained as a prophage within its host. Here we show that lysogeny occurs in natural populations of an autotrophic picoplankton (Synechococcus) and that there is a seasonal pattern to this interaction. Because lysogeny confers immunity to infection by related viruses, this process may account for the resistance to viral infection seen in common forms of autotrophic picoplankton.

Bacteriophages↗
PubMed1996

The CII protein of bacteriophage 186 establishes lysogeny by activating a promoter upstream of the lysogenic promoter.

We have shown previously that the cII gene product of the non-lambdoid temperate bacteriophage 186 is required for the establishment of lysogeny. We show here that CII, a potential helix-turn-helix DNA-binding protein, establishes lysogeny by activating a promoter (PE) which spans the apl/cII intergenic region, upstream of the lysogenic promoter, PL. The start site of the PE transcript (+1) has been mapped by primer extension and we have identified the CII binding determinants at PE by DNase I footprinting. CII binds to inverted repeat sequences separated by two turns of the helix, with binding half-sites centred at the 38 and -58 positions of PE. Oligomerisation studies with purified CII protein indicate that a CII tetramer may be the species that binds to this site. We also show that PE is subject to direct negative feedback by the CI repressor.

Base Sequence↗
PubMed1971

Adenosine 3':5'-cyclic monophosphate concentration in the bacterial host regulates the viral decision between lysogeny and lysis.

Mutants of Salmonella typhimurium defective in adenylate cyclase (cya gene) or in cAMP receptor protein (crp gene) are lysogenized at reduced frequency by phage P22. One class of the bacterial mutants with an altered RNA polymerase (rif gene) is also lysogenized at reduced frequency. In the three types of mutant bacteria, the phage's decision between lysogeny and lysis is shifted to lysis and the phage form clear plaques. We propose that in wild-type bacteria the cAMP-receptor protein, in combination with cAMP, activates bacterial RNA polymerase to transcribe certain phage genes that are required for efficient lysogenization. Under conditions of strong catabolite repression, when the supply of energy and biosynthetic components is abundant and the concentration of cAMP is low, the phage would multiply and lyse the cell. When the supply of energy is deficient and the concentration of cAMP is high, the phage would lysogenize the cell. Phage mutants have been isolated that form turbid plaques on the three classes of bacterial mutants due to a higher frequency of lysogeny. These phage mutants have been shown by complementation to be defective in the same gene, which we have called the cly gene. These cly mutants lysogenize the wild-type bacteria with a 99% frequency and, thus, do not form plaques on them. Other kinds of bacterial mutants are also lysogenized at reduced frequency by phage P22. They may be altered in other physiological control systems that influence the frequency of lysogenization.

Adenylyl Cyclases↗
PubMed1983

Toxic shock syndrome and lysogeny in Staphylococcus aureus.

Lysogeny, or the presence of temperate bacteriophage, was demonstrated, by means of two Staphylococcus aureus indicator strains, in 11 of 12 strains of S. aureus isolated from patients with toxic shock syndrome. Only 1 of 18 strains of S. aureus that were not associated with toxic shock syndrome showed the presence of bacteriophage. A laboratory strain of S. aureus was lysogenized by bacteriophage from two of the toxic shock-associated strains. These results add support to the theory that lysogeny by one or more bacteriophage in certain strains of S. aureus may be responsible for the pathogenesis of toxic shock syndrome.

Bacterial Toxins↗
PubMed2001

First evidence of lysogeny in Propionibacterium freudenreichii subsp. shermanii.

Dairy propionic acid bacteria, particularly the species Propionibacterium freudenreichii, play a major role in the ripening of Swiss type cheese. Isometric and filamentous bacteriophages infecting P. freudenreichii have previously been isolated from cheese. In order to determine the origin of these bacteriophages, lysogeny of P. freudenreichii was determined by isometric bacteriophage type analysis. The genomic DNA of 76 strains were hybridized with the DNA of nine bacteriophages isolated from Swiss type cheeses, and the DNA of 25 strains exhibited strong hybridization. Three of these strains released bacteriophage particules following UV irradiation (254 nm) or treatment with low concentrations of mitomycin C. A prophage-cured derivative of P. freudenreichii was readily isolated and subsequently relysogenized. Lysogeny was therefore formally demonstrated in P. freudenreichii.

Bacteriophages↗
PubMed2006

Unstable lysogeny and pseudolysogeny in Vibrio harveyi siphovirus-like phage 1.

Exposure of Vibrio harveyi (strain VH1114) to V. harveyi siphovirus-like phage 1 (VHS1) resulted in the production of a low percentage of lysogenized clones of variable stability. These were retrieved most easily as small colonies within dot plaques. Analysis revealed that VHS1 prophage was most likely carried by VH1114 as an episome rather than integrated into the host chromosome. In the late exponential growth phase, lysogenized VH1114 continuously produced VHS1 but also gave rise to a large number of cured progeny. The absence of phage DNA in the cured progeny was confirmed by the absence of VHS1 DNA in Southern blot and PCR assays. Curiously, these very stable, cured subclones did not show the parental phenotype of clear plaques with VHS1 but instead showed turbid plaques, both in overlaid lawns and in dot plaque assays. This phenotypic difference from the original parental isolate suggested that transient lysogeny by VHS1 had resulted in a stable genetic change in the cured clones. Such clones may be called pseudolysogens (i.e., false lysogens), since they have undergone transient lysogeny and have retained some resistance to full lytic phage development, despite the loss of viable or detectable prophage.

Animals↗
PubMed1973

Lysogeny in lactic streptococci producing and not producing nisin.

Eighty-seven strains of lactic streptococci (46 of Streptococcus lactis, 24 of S. diacetilactis, and 17 of S. cremoris) were tested for lysogeny; 12 S. lactis strains produced nisin. Lysogeny was found in five S. lactis strains (two of them were nisin producers) and in two S. diacetilactis strains. Four S. lactis and two S. diacetilactis lysogens liberated phages both spontaneously and after ultraviolet treatment, and one S. lactis strain liberated phages spontaneously only. No lysogens were found among the S. cremoris strains tested. An initial characterization of the lysogens and their phages was made. The lytic spectrum of some of the examined phages was very narrow (homospecific), whereas that of others was wide, including strains of the three investigated species.

Bacteriolysis↗
PubMed1991

Multiple effects of Fis on integration and the control of lysogeny in phage lambda.

Fis is a small, basic, site-specific DNA-binding protein present in Escherichia coli. A Fis-binding site (F) has been previously identified in the attP recombination site of phage lambda (J. F. Thompson, L. Moitoso de Vargas, C. Koch, R. Kahmann, and A. Landy, Cell 50:901-908, 1987). The present study demonstrates that in the absence of the phage-encoded Xis protein, the binding of Fis to F can stimulate integrative recombination and therefore increase the frequency of lambda lysogeny in vivo. Additionally, Fis exerts a stimulatory effect on both integration and lysogeny that is independent of binding to the attP F site. Maintenance of the lysogenic state also appears to be enhanced in the presence of Fis, as shown by the increased sensitivity of lambda prophages encoding temperature-sensitive repressors to partial thermoinduction in a fis mutant. In the presence of Xis, however, Fis binding to F interferes with integration by stimulating excision, the competing back-reaction. Since Fis stimulates both excision and integration, depending on the presence or absence of Xis, respectively, we conclude that Xis binding to X1 is the key determinant directing the formation of an excisive complex.

Attachment Sites, Microbiological↗
PubMed1993

Genes for the establishment and maintenance of lysogeny by the temperate coliphage 186.

To identify the genes in coliphage 186 that are required for lysogeny, we isolated clear-plaque mutants. Complementation studies and DNA sequencing identified two genes, the cI gene for the immunity maintenance repressor and the cII gene, which is required only for the establishment of lysogeny. One mutant carried a change in the LexA-binding site controlling expression of the antirepression protein Tum.

Bacterial Proteins↗
PubMed1968

Second locus of bacteriophage P22 necessary for the maintenance of lysogeny.

A temperature-sensitive allele of a locus of phage P22, known to be involved in establishment of lysogeny, has been isolated. This mutant, P22 ts mnt, forms stable lysogens at 30 C which are induced by heating to 43 C. This shows that this locus is involved in the maintenance of lysogeny. The ts mnt locus is about 18 recombination units away from the c region. The wild allele, mnt(+), is dominant over mnt and is responsible for a cytoplasmically diffusible product.

Chromosome Mapping↗
PubMed1975

[Chemical induction of lysogeny of Staphylococcus aureus (author's transl)].

Concerning the chemical induction of lysogeny of Staphylococcus aureus only little is known. Therefore, we performed induction experiments on 43 Staph, aureus strains using nine mutagenic substances and 15 chemotherapeutics. Only three of the nine mutagenic substances (beta-propiolacton, nitrosoguanidin and mitomycin C) and six of the 15 chemotherapeutics (penicillin G, ampicillin, cephalothin, nebacetin, novobiocin and nalidixie acid) showed inducing effects. Our results demonstrated furtheron that the lysogeny inducing ability is dependent on strains and substances used.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Lysogeny of Rhizobium japonicum and the sensitivity of these cultures to phages isolated from soil].

Twenty cultures of Rhizobium japonicum of various origin were tested for lysogeny using a cross technique with a preliminary UV induction and without it as well as by electron microscopy. None of the cultures was found in the lysogenic state. Phages active against Rh. japonicum were detected in four soil samples on which soybean plants were grown; 27 phages were isolated by the enrichment method and 3 phages without enrichment. The phages were capable of lysis of only Rh. japonicum cultures and differed in the spectrum of lytic action. Some of them were very specific: 9 phages caused lysis of only one among the 28 tested cultures, and 10 phages lysed 2 cultures. Phages with a broad spectrum of lytic action induced lysis of 7-9 cultures. Some of the phages isolated from soils of different type were identical and some were similar in the spectrum of lytic action. Among 28 cultures of Rh. japonicum, 8 cultures were sensitive to all of the 30 phages isolated from soil and 2 cultures were sensitive to most of the phages; the remaining cultures were sensitive to 1-8 phages. Phages and cultures have been selected which can be used for experimental preparation of lysogenic systems and further studies of lysogeny in Rh. japonicum.

Bacteriophage Typing↗
PubMedDate not supplied

[The phage sensitivity and lysogeny of cultures of Streptococcus pyogenes group A isolated in different streptococcal infections].

The collection of moderate phages of S. pyogenes, group A, had been created earlier. As shown in this work, group A streptococcal cultures isolated from patients with rheumatism, glomerulonephritis and tonsillitis exhibited different sensitivity to the phages of this collection: the cultures were lyzed by phages of groups II and III in rheumatism, group III in tonsillitis and group I in glomerulonephritis. The study revealed that lysogeny was widely spread among S. pyogenes strains isolated from patients with different diseases under study. Most frequently occurred among cultures isolated from tonsillitis patients. In this disease only phage-resistant streptococcal cultures proved to be lysogenic. Lysogeny was found among both phage-sensitive and phage-resistant cultures in rheumatism and especially in glomerulonephritis.

Bacteriophage Typing↗
PubMed1984

Phage-typing scheme of Salmonella bareilly based on lysogeny.

A phage-typing system of Salmonella bareilly based on lysogeny is presented. In the present study which comprised 378 strains, fifteen different phage types named 'a' through 'o' were established. With this system 70.3% of the strains could be typed by using five indicator strains.

Animals↗
PubMed2003

Effects of lysogeny of Shiga toxin 2-encoding bacteriophages on pulsed-field gel electrophoresis fragment pattern of Escherichia coli K-12.

Escherichia coli K-12 lysogens of three different Shiga toxin 2 (Stx2)-encoding bacteriophages were examined for variability in their pulsed-field gel electrophoresis (PFGE) fragment patterns. The PFGE fragment patterns could be classified into three types (i.e., PFGE types B, C, and D). For the PFGE type D, a 255-kbp fragment present in the original K-12 strain was apparently shifted by the size of Stx 2-encoding phage genomic DNA (ca. 65 kbp) to the position at 320 kbp. In contrast, the types B and C showed the above fragment shift plus further 6- and 10-fragment differences, respectively, from the original K-12 strain. The evidence suggests that even a single genetic event like lysogeny can cause marked genotypic modification of the host strain.

Bacteriophages↗
PubMed1989

The influence of the O-antigen and the capsular polysaccharide on the establishment of PlCmts lysogeny in Klebsiella pneumoniae.

The O-antigen of the lipopolysaccharide in Klebsiella pneumoniae caused a significant reduction in the frequency of establishment of PlCmts lysogeny, while the capsular polysaccharide showed no effect on this frequency. The bacterial receptor for PlCmts are the lipopolysaccharide-core oligosaccharides, the results suggest that K. pneumoniae strains with an O-antigen in their lipopolysaccharide have a poorly accessible lipopolysaccharide-core (the PlCmts bacterial receptor), while K. pneumoniae strains lacking the O-antigen have a highly accessible lipopolysaccharide-core. The accessibility of the receptor is independent of the K antigen (capsular polysaccharide).

Antigens, Bacterial↗
PubMed1983

Lysogeny and other characteristics of Staphylococcus hyicus isolated from chickens.

Lysogeny was readily demonstrated among strains of Staphylococcus hyicus that were isolated from chickens. Susceptibility to phage lysis was affected by prophage immunity, but lipase activity and erythromycin resistance were not affected by the presence of temperate phage. In contrast to previously published results, lipase-negative strains of S. hyicus were relatively common and the use of selective media based on lipase activity would have been unsuitable for detection of the S. hyicus strains examined.

Animals↗