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1.
Dana L. Swenson Kyoung-Jin Kim Erich W. Six Steven Clegg 《Molecular & general genetics : MGG》1994,244(2):216-218
The gene fimU, located on a recombinant plasmid carrying the Salmonella typhimurium type 1 fimbrial gene cluster is closely related to the Escherichia coli tRNA gene argU. The fimU gene complements an E. coli argU mutant that is a P2 lysogen, thereby allowing the phage P4 to grow in this strain but preventing the growth of phage lambda. In addition, fimU was shown to be involved in fimbrial expression since transformants of the E. coli argU mutant could produce fimbriae only in the presence of fimU but not in its absence, whereas in an E. coli argU
+ strain fimbriation did not require the fimU gene. 相似文献
2.
Shigeru Iida 《Plasmid》1980,3(3):278-290
Restriction cleavage analysis identified a P1CmSmSuTc plasmid isolated by Mise and Arber (1976) (Virology 69, 191–205) as a cointegrate between bacteriophage P1 and the R plasmid R100. Cointegration occurred by reciprocal recombination between the IS1 element of P1 and IS1b of R100. It involved neither gain nor loss of genetic material, so that the cointegrate carries three IS1 elements in the same orientation. The cointegrate propagates with relatively high stability as plasmid in Escherichia coli host bacteria. It displays the Tra+ functions of R100, incompatibility FII of R100, and incompatibility Y of P1, Res+ (P1), Mod+ (P1) functions of P1 and P1 immunity. Production of P1 phage particles is inducible as for wild type P1. However, because of the large genome size of 180 kb, progeny phage particles contain only a fraction (about 100 kb) of the cointegrate genome. Because of cyclic permutation all genome regions are equally represented in a population of the phage particles of an induced lysate. Occasionally, reciprocal recombination between IS1 elements allows the restoration of the P1 genome. These segregants are found as plaque formers at a rate of about 1 per 300 phage particles in induced lysates. 相似文献
3.
Recombinant P4 bacteriophages propagate as viable lytic phages or as autonomous plasmids in Klebsiella pneumoniae 总被引:12,自引:0,他引:12
Summary We demonstrate the use of bacteriophage P4 as a molecular cloning vector in Klebsiella pneumoniae. A hybrid P4 phage, constructed in vitro, that contains a K. pneumoniae hisDG DNA fragment can be propagated either as a lytic viable specialized transducing phage or as an autonomous, self-replicating plasmid. Hybrid P4 genomes existing as plasmids can be readily converted into non-defective P4-hybrid phage particles by superinfection with helper phage P2. Infection of a K. pneumoniae hisD non-P2 lysogen with P4-hisD hybrid phage results in approximately 90% of the infected cells becoming stably transduced to HisD+. Because P4 interferes with P2 growth, high titre stocks of P4 hybrid phages are relatively free (10-6) of P2 contamination. The hisG gene product was detected in ultraviolet light irradiated host cells infected by the P4-hisDG hybrid phage. A mutant of P4 (P4sidl) that directs the packaging of P4 DNA into P2 sized capsids should permit the construction of hybrid phages carrying 26 kilobase inserts. 相似文献
4.
High-frequency plasmid transductions in Lactobacillus delbrueckii subsp. lactis and subsp. bulgaricus strains mediated by pac-type bacteriophages were observed and further investigated. The frequency of plasmid transduction by phages LL-H and LL-S attained levels of from 0.10 to about 1 with plasmid pX3, but only about 2 × 10−2 with plasmid pJK650. Infection of L. delbrueckii subsp. lactis strain LKT(pX3) or ATCC 15808(pX3) with phage LL-H resulted in intensive concatemerization of plasmid pX3, and most progeny phage particles contained concatemers of plasmid DNA instead of phage LL-H DNA. The synthesis of phage LL-H DNA was depressed. No evident homology or recombination was observed between phage LL-H DNA and plasmid pX3. The unusually high frequency of plasmid pX3 transduction by phage LL-H could be considered to result from specific interaction(s) between a particular phage and plasmid. These interactions may include pX3-mediated blockage of phage LL-H DNA replication and effective use of a particular pac-like site located about 1 kb from BglII in the smaller NdeI-BglII fragment of plasmid pX3. Phage LL-H together with plasmid vector pX3 could be used as effective plasmid transduction tools for genetic engineering of L. delbrueckii subsp. lactis and subsp. bulgaricus strains. 相似文献
5.
We studied the growth characteristics of a pair of Escherichia coli strains, isogenic apart from the possession of a nonconjugative plasmid. There was no difference between the two strains when they were grown separately. In mixed culture, a second slow phase of growth that normally occurred following the end of rapid exponential growth, was absent from the plasmid-carrying strain. This resulted in a considerable decrease in the proportion of the cells that carried the plasmid after overnight incubation. The effect of different conditions of growth is reported. The plasmid-carrying strain survived extended incubation (150 days at 37°C) as well as did the plasmid free strain separately. In a mixture, the proportion of plasmid-carrying cells declined rapidly, and none was detected after 100 days. 相似文献
6.
Tanyashin V. I. Zimin A. A. Shlyapnikov M. G. Boronin A. M. 《Russian Journal of Genetics》2003,39(7):761-772
Transduction of antibiotic resistance determinants of the plasmid pBR322 with pseudoT-even bacteriophages RB42, RB43, and RB49 was studied. It is established that antibiotic resistance determinants of plasmid pBR322 fromEscherichia coli recA
+ and recA
– donor strains do not differ significantly in respect to the efficiency of transduction. Amber mutants RB43-21, RB43-33, and a double amber mutant RB43am21am33 were obtained. These mutants facilitated transduction experiments in some cases. Transduction of antibiotic resistance markers of the vector plasmid pBR325 and recombinant plasmid pVT123, containing a DNA fragment with hoc–segE–uvsW genes of phage T4, was studied. The frequency of appearance of transductants resistant to pseudoT-even bacteriophages used in transduction was determined, and the sensitivity of resistant transductants to 32 RB bacteriophages and also to phages , T2, T4, T5, T6, T7, and BF23 was estimated. The efficiency of plating pseudoT-even bacteriophages RB42 and RB43 on strain E. coli 802 himA
hip carrying mutations in genes that encode subunits of the Integration Host Factor (IHF) was shown to be higher than on isogenic strain E. coli 802. The growth of pseudoT-even bacteriophages limitedin vivo by modification–restriction systems of chromosomal (EcoKI, EcoBI), phage (EcoP1I), and plasmid (EcoRI, EcoR124I, and EcoR124II) localization was analyzed. It was shown that these phages were only slightly restricted by the type I modification–restriction systemsEcoBI, EcoR124I, and EcoR124II. Phage RB42 was restricted by systems EcoKI, EcoP1I, and EcoRI; phage RB43, by systems EcoKI and EcoRI; and phage RB49, by the EcoRI modification–restriction system. 相似文献
7.
Dana L. Swenson Kyoung-Jin Kim Erich W. Six Steven Clegg 《Molecular genetics and genomics : MGG》1994,244(2):216-218
The gene fimU, located on a recombinant plasmid carrying the Salmonella typhimurium type 1 fimbrial gene cluster is closely related to the Escherichia coli tRNA gene argU. The fimU gene complements an E. coli argU mutant that is a P2 lysogen, thereby allowing the phage P4 to grow in this strain but preventing the growth of phage lambda. In addition, fimU was shown to be involved in fimbrial expression since transformants of the E. coli argU mutant could produce fimbriae only in the presence of fimU but not in its absence, whereas in an E. coli argU + strain fimbriation did not require the fimU gene. 相似文献
8.
9.
《Bioscience, biotechnology, and biochemistry》2013,77(4):648-651
Lactobacillus acidophilus TK8912 produces an antibacterial substance, designated acidocin 8912, which is active against strains of Lactobacillus and Lactococcus. Of all conditions tested, the production of acidocin 8912 was maximum at 30°C in MRS broth. Acidocin 8912 was stable to heat treatment (120°C for 20min), but completely inactivated by protease treatment. Curing a plasmid pLA103 resulted in the loss of both acidocin 8912 production (Acd+) and host immunity (Acdr). A plasmid-cured strain, TK1–4 (Acd- Acd8), was transformed to Acd+Acdr with the pLA103 plasmid. These results provided the first direct evidence in lactobacilli for involvement of this plasmid in bacteriocin production and immunity. 相似文献
10.
We examined the survival of a host Escherichia coli K-12 bacterium containing two transferable plasmids (pLM2, pSL222-4) and one poorly mobilizable plasmid (pBR322), and the transfer of these three plasmids to endogenous bacteria in the human intestinal tract. The survival of this plasmid-carrying host organism in four human volunteers was 3.5 to 6 days at recovery rates of 10?1 to 10?4. This finding was similar to our previous survival data on the same organism bearing a single plasmid. The K-12 strain appeared to be under a strong selective disadvantage in the human gut, since, even when bearing a tetracycline-resistant plasmid, its titer did not increase despite the administration of tetracycline. Studies of transferability showed that, while the transfer-depressed incFII plasmid pSL222-4 transferred at a frequency of 10?1 in culture, its transfer in the human gut was much less frequent. The number of new recipients per donor cell ingested was about 10?5, which included new recipients arising by multiplication. The recovery of pSL222-4 transcipients was enhanced by the administration of tetracycline on day 6. Neither the transfer-repressed, broad host range incP plasmid pLM2, nor the plasmid pBR322, could be detected in any endogenous host bacteria. Using the transfer and mobilization frequencies obtained in culture and the number of new recipients of pSL222-4 in the intestinal tract, we estimated that any in vivo mobilization of pBR322 to a new recipient could not occur at a frequency higher than 10?12. 相似文献
11.
Summary Fragments of DNA of the temperate phage P2, generated by treatment with the restriction enzyme PstI, have been cloned into the plasmid pBR322. One such fragment, which has its endpoints within phage genes T and C, carries the structural P2 int gene as well as its promoter and the phage att site. When introduced into a suitable bacterial host, the cloned fragment mediates the integration and excision of int
- mutants of P2 and recombination within the phage att site in mixed infection. All these activities are independent of the orientation of the fragment within the plasmid.When introduced into minicells, the fragment produces, in addition to the products of genes D and U, a protein of 35–37,000 daltons identified as the int protein. A study of the map location of two amber int mutants, together with the sizes of the polypeptides they produce, indicates that the P2 int gene is transcribed from right to left on the P2 map, i.e. starting near gene C and proceeding toward att. 相似文献
12.
《Journal of Fermentation Technology》1988,66(4):409-415
Lac+ recombinant plasmids encoding a β-galactosidase fused protein and lactose permease of Escherichia coli were introduced Zymomonas mobilis. The fused protein was expressed with 450 to 5,860 Miller units of β-galactosidase activity, and functioned as lactase. Raffinose uptake by Z. mobilis CP4 was enhanced in the plasmid-carrying strain over the plasmid-free strain, suggesting that the lactose permease was functioning in the organism. Z. mobilis carrying the plasmid could produce ethanol from lactose and whey, but could not grow on lactose as the sole carbon source. It was found that the growth of the organism was inhibited by either galactose of the galactose liberated from lactose. 相似文献
13.
Witold Zurkowski 《Molecular & general genetics : MGG》1981,181(4):522-524
Summary When the nodulating Rhizobium trifolii strain 24Vior containing plasmid RP4 was conjugated with the non-nodulating R. trifolii mutant strain 24StrrNod-35, plasmid RP4 was transferred at a frequency 10-3–10-4. Two out of nearly three thousand tested transconjugants which contained plasmid RP4 had acquired the ability to form nodules on clovers. Molecular studies of the DNA of both these nodulating transconjugants showed the presence of plasmid RP4 and another plasmid which was not found in the original recipient strain. The size of this second plasmid corresponded to that of the plasmid pWZ2, the elimination of which was correlated with irreversible loss of the nodulating ability of R. trifolii strain 24 (Zurkowski and Lorkiewicz 1979). Plasmid RP4 was eliminated from cells by ethidium bromide, without the loss of nodulating properties. The nodulation capacity, however, was eliminated from transconjugants after incubation of bacteria at elevated temperature. Non-nodulating clones obtained after such incubation did not contain the plasmid pWZ2. The results indicate that the plasmid pWZ2 is a necessary element for induction of nodules by R. trifolii, and that it can be mobilized by plasmid RP4. 相似文献
14.
Summary The DNA of an E. coli K12 strain harboring ten wildtype Mu prophages was restricted with endonuclease EcoRI, and the fragments ligated into the plasmid vector pMB9. Upon transformation of a strain carrying a heat inducible (Mu cts62) prophage, one temperature-resistant transformant was isolated. This transformant strain harbors the hybrid plasmid pKN001, containing the EcoRI.C fragment of Mu DNA as shown by restriction and heteroduplex analysis. Stable transformants of pKN001 are immune to superinfection with phage Mu. Transformation of superinfection with phage Mu. Transformation of Mu sensitive bacteria with pKN001 results in killing of the recipients (10-4 surviving bacteria). The killing function is not expressed upon transformation of Mu-immune (lysogenic) bacteria.This paper is dedicated by EGB to Dr. Luis F. Leloir, on the occasion of his 70th birthday 相似文献
15.
16.
《Bioscience, biotechnology, and biochemistry》2013,77(6):1047-1048
A Streptomyces plasmid, pR4C2, with an inserted DNA fragment of R4 phage, was encapsidated into R4 phage particles in vivo and transduced to Streptomyces lividans at 3 ×10?6CFIJ/PFU. Formation of transducing phage was dependent on the inserted R4 DNA, and some of the transducing phages had larger DNA than R4 phage. A possible transduction mechanism through plasmid-phage cointegrate formation in vivo is discussed. 相似文献
17.
Plaque forming specialized transducing phage P1: Isolation of P1CmSmSu, a precursor of P1Cm 总被引:6,自引:0,他引:6
Summary
E. coli strains lysogenic for various types of P1-R hybrids were isolated. These carry all the essential genes for vegetative phage production and lysogenization including P1 immunity and P1 incompatibility, together with drug resistance genes derived from the R plasmid NR1. In particular, P1Cm and P1CmSmSu derivatives were studied. When strains lysogenic for these phages were induced in the absence of helper phage, yields of phage particles as high as with wild type P1 were obtained. All P1Cm phages isolated were of plaque forming type and usually every plaque contained Cmr lysogens. Lysates of P1CmSmSu lysogens transduced CmrSmrSur at high frequency and they formed plaques with an efficiency of 10-4 to 10-2 per phage particle. Only a minority of these plaques contained drug resistant bacteria. CmrSmrSur transductants isolated from bacteria infected at a high multiplicity with phage P1CmSmSu were lysogens for the original P1CmSmSu. In contrast, CmrSmrSur transductants isolated after infection at low multiplicity appeared to carry the CmrSmrSur markers integrated into the host chromosome. The results described suggest that P1CmSmSu prophages carry the resistance genes transposed into the P1 genome without in principle causing a loss of essential gene functions. However, since these prophages are longer than the wild type P1 genome, the DNA packaged into phage particles has a reduced redundancy which seriously affects the reproduction and lysogenization abilities.Plaque forming P1Cm can be obtained from P1CmSmSu. Thus, P1CmSmSu is a precursor of P1Cm. P1Cm is also obtainable from P1 and NR1 under the recA
- condition. The mechanism of formation of plaque forming P1Cm is discussed. 相似文献
18.
C55 bacteriocin produced by ETB‐plasmid positive Staphylococcus aureus strains is a key factor for competition with S. aureus strains
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Miki Kawada‐Matsuo Fariha Shammi Yuichi Oogai Norifumi Nakamura Motoyuki Sugai Hitoshi Komatsuzawa 《Microbiology and immunology》2016,60(3):139-147
19.
Summary The possibility that a strain lysogenic for phage P2 could be brought into the so-called antiimmune state in which the synthesis of phage repressor is permanently turned off, was tested in the following way. Two lysogenic strains that could be derepressed at 42°C were prepared. In one, the prophage had, in addition to a temperature-sensitive repressor mutation (c5), amber mutations in the two early genes A and B. In the other, the prophage had an unknown defect that blocked expression of the A and B genes. Both strains could multiply at 42° C as well as or almost as well as a non-lysogen. After the strains had grown for several generations at 42° C, they were returned to 30° and the resynthesis of repressor was followed by measuring the restoration of immunity to super-infection. In both cases, the immunity returned slowly over a period of 2 to 3 h. In a strain made doubly lysogenic for two amA amB c5 prophages, immunity was restored at a more rapid rate, suggesting that the rate of restoration depended mainly on the number of copies of repressor gene present. Attempts to demonstrate channeling towards the lytic pathway in the derepressed lysogens was also negative. The temperature treatment tended instead to increase the frequency of lysogenization of superinfecting P2. Thus, the presence of a system, similar to the cro system described for phage lambda, to regulate repressor synthesis in phage P2 could not be demonstrated. 相似文献
20.
Masayoshi Maeshima Ikuzo Uritani Tadashi Asahi 《Bioscience, biotechnology, and biochemistry》2013,77(10):2493-2494
Cosmid pR4Cl is a derivative of multicopy plasmid pIJ365 which has an insertion of the cos (cohesive end site) region of actinophage R4 [T. Morino, H. Takahashi and H. Saito, Mol. Gen. Genet., 198, 228 (1985)]. When the donor R4 phage was propagated in S. lividans carrying the plasmid, the phage lysate contained transducing particles which encapsulated head-to-tail concatemers of the plasmid DNA. These particles could mediate transfer of the plasmid at a high frequency. We examined conditions that gave a maximum transduction frequency of cosmid pR4Cl. Conditions which depress R4 phage propagation, such as incubation of recipient S. parvulus at a high temperature, improved the frequency. Obviously such conditions minimized the lethal effect of viable phage propogation. The highest transduction frequency obtained so far was around 3 × 10-3 transductants per infected phage when S. lividans was used as the recipient. This was about 30 per cent of the cosmid transducing particles estimated from the cosmid DNA content in the transducing lysate. The significance of cosmid transduction for gene manipulation in Streptomyces strains is also discussed. 相似文献