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pBR322 and Protein Expression Systems in E. coli
The extensive variety of plasmid-based expression systems in E. coli resulted from the fact that there is no single strategy for achieving maximal expression of every cloned gene. Although a number of strategies have been implemented to deal with problems associated to gene transcription and translation, protein folding, secretion, location, posttranslational modifications, particularities of different strains, and the like and more integrated processes have been developed (1,2), the basic plasmid-borne elements and their interaction with the particular host strain will influence the overall expression system and final productivity (3) (seeChapters 1–3).
Plasmid vector pBR322 (4) is a well-established multipurpose cloning vector in laboratories worldwide, and a large number of derivatives have been created for specific applications and research purposes, including gene expression in its natural host, E. coli, and few other bacteria. The early characterization of the molecule, including its nucleotide sequence, replication and maintenance mechanisms, and determination of its coding regions, accounted for its success, not only as a universal cloning vector, but also as a provider of genes and an origin of replication for other intraspecies vectors (5,6). Since the publication of the aforementioned reviews, novel discoveries pertaining to these issues have appeared in the literature that deepen the understanding of the plasmid’s features, behavior, and impact in gene expression systems, as well as some important strain characteristics that affect plasmid replication and stability.
The objectives of this review include updating and discussing the new information about (1) the replication and maintenance of pBR322; (2) the host-related modulation mechanisms of plasmid replication; (3) the effects of growth rate on replication control, stability, and recombinant gene expression; (4) ways for plasmid amplification and elimination. Finally, (5) a summary of novel ancillary studies about pBR322 is presented.
Key WordsIntegration excision replication Rop/Rom
Balbás, P. (2001) Understanding the art of producing protein and non protein molecules in E. coli
. Mol. Biotechnol.
, 251–267.PubMedGoogle Scholar
Swartz, J. R. (2001) Advances in Escherichia coli
production of therapeutic proteins. Curr. Opin. Biotechnol.
, 195–201.PubMedGoogle Scholar
Balbás, P. and Bolívar, F. (1990) Design and construction of expression plasmid vectors in Escherichia coli
. Methods Enzymol.
, 3–40.Google Scholar
Bolívar, F., Rodríguez, R. L., Greene, P. J., Betlach, M. C., Heyneker, H. L., Boyer, H. W., et al. (1976) Construction and characterization of new cloning vehicles. II. A multipurpose cloning system. Gene
, 95–113.Google Scholar
Balbás, P., Soberón, X., Merino, E., Zurita, M., Lomelí, H., Valle, F., et al. (1986) Plasmid vector pBR322 and its special-purpose derivatives: a review. Gene
, 3–40.PubMedGoogle Scholar
Balbás, P., Soberón, X., Bolívar, F., and Rodríguez, R. L. (1988) The plasmid, pBR322, in Vectors. A Survey of Molecular Cloning Vectors and Their Uses
(Rodríguez, R. L. and Denhardt, D. T., eds.) Butterworth, pp. 5–41.Google Scholar
Covarrubias, L., and Bolívar, F. (1982) Construction and characterization of new cloning vehicles. VI. Plasmid pBR329, a new derivative of pBR328 lacking the 482-base-pair inverted duplication. Gene
, 79–89.PubMedGoogle Scholar
Mohanty, B. K., Sahoo, T., and Bastia, D. (1998) Mechanistic studies on the impact of transcription on sequence-specific termination of DNA replication and vice versa. J. Biol. Chem.
, 3051–3059.Google Scholar
Bussiere, D. E. and Bastia, D. (1999) Termination of DNA replication of bacterial and plasmid chromosomes. Mol. Microbiol.
, 1611–1618.PubMedGoogle Scholar
Ohmori, H., Murakami, Y., and Nagata, T. (1987) Nucleotide sequences required for a ColE1-type plasmid to replicate in Escherichia coli
cells with or without RNase H. J. Mol. Biol.
, 223–234.Google Scholar
Chiang, C. S., Xu, Y. C. and Bremer, H. (1991) Role of DnaA protein during replication of plasmid pBR322 in Escherichia coli
. Mol. Gen. Genet.
, 435–442.PubMedGoogle Scholar
Minden, J. S. and Marians, K. J. (1985) Replication of pBR322 DNA in vitro with purified proteins. Requirement for topoisomerase I in the maintenance of template specificity. J. Biol. Chem.
, 9316–9325.PubMedGoogle Scholar
Parada, C. A. and Marians, K. J. (1989) Transcriptional activation of pBR322 DNA can lead to duplex DNA unwinding catalyzed by the Escherichia coli
preprimosome. J. Biol. Chem.
, 15120–15129.PubMedGoogle Scholar
Masai, H. and Arai, K. (1989) Escherichia coli dnaT
gene function is required for pBR322 plasmid replication but not for R1 plasmd replication. J. Bacteriol.
, 2975–2980.PubMedGoogle Scholar
Del Solar, G., Giraldo, R., Ruiz-Echevarría, M. J., Espinosa, M. and Díaz-Orejas, R. (1998) Replication and control of circular bacterial plasmids. Microbiol. Mol. Biol. Rev.
, 434–464.PubMedGoogle Scholar
Lee, E. H. and Kornberg, A. (1991) Replication deficiencies in priA
mutants of Escherichia coli
lacking the primosomal replication n’protein. Proc. Natl. Acad. Sci. USA
, 3029–3032.Google Scholar
Lin-Chao, S. and Bremer, H. (1987) Activities of the RNA I and RNA II promoters of plasmid pBR322. J. Bacteriol.
, 1217–1222.PubMedGoogle Scholar
Brenner, M. and Tomizawa, J. (1991) Quantitation of ColE1-encoded replication elements. Proc. Natl. Acad. Sci. USA
, 405–409.PubMedGoogle Scholar
Liang, S., Bipatnath, M., Xu, Y., Chen, S., Dennis, P., Ehrenberg, M., et al. (1999) Activities of constitutive promoters in Escherichia coli
. J. Mol. Biol.
, 19–37.PubMedGoogle Scholar
Polisky, B. (1988) ColE1 replication control circuitry: sense from antisense. Cell
, 929–932.PubMedGoogle Scholar
Chiang, C. S. and Bremer, H. (1991b) Maintenance of pBR322-derived plasmids without functional RNA I. Plasmid
, 186–200.PubMedGoogle Scholar
Ivanov, I., Yavashev, L., Gigova, I., Alexciev, K., and Christo, C. (1988) A conditional high-copy-number plasmid derivative of pBR322. Microbiologica
, 95–99.PubMedGoogle Scholar
Nugent, M. E., Smith, T. J. and Tacon, W. C. (1986) Characterization and incompatibility properties of ROM-derivatives of pBR322-based plasmids. J. Gen. Microbiol.
, 1021–1026.PubMedGoogle Scholar
Lin-Chao, S. and Cohen, S. N. (1991) The rate of processing and degradation of antisense RNA I regulates replication of ColE1-type plasmids in vivo
, 1233–1242.PubMedGoogle Scholar
Bouvet, P. and Belasco, J. G. (1991) Control of RNAseE-mediated RNA degradation by 5′-terminal base-pairing in E. coli
, 488–491.Google Scholar
Kushner, S. R. (1996) mRNA decay. In Escherichia coli
. Cellular and Molecular Biology. 2nd ed. (Niedhardt et al.
, eds.), ASM Press, Washington, D.C.Google Scholar
Jung, Y. H. and Lee, Y. (1995) RNAses in ColE1 DNA metabolism. Mol. Biol. Rep.
, 195–200.PubMedGoogle Scholar
Binnie, U., Wong, K., McAteer, S. and Masters, M. (1999) Absence of RNAse III alters the pathway by which RNA I, the antisense inhibitor of ColE1 replication, decays. Microbiology
, 3089–3100.PubMedGoogle Scholar
Kaberdin, V. R., Chao, Y. H. and Lin-Chao, S. (1996) RNAse E cleaves at multiple sites in bubble regions of RNA I stem-loops yielding products that dissociate differentially from the enzyme. J. Biol. Chem.
, 13103–13109.PubMedGoogle Scholar
Lin-Chao, S., Wong, T. T., McDorwall, K. J., and Cohen, S. N. (1994) Effects of nucleotide sequence on the specificity of rne
-dependent and RNAseE-mediated cleavages of RNA I encoded by the pBR322 plasmid. J. Biol. Chem.
, 10797–10803.PubMedGoogle Scholar
Lopilato, J., Bortner, S., and Beckwith, J. (1986) Mutations in a new chromosomal gene of Escherichia coli
K-12, reduce plasmid copy number of pRB322 and its derivatives. Mol. Gen. Genet.
, 285–290.PubMedGoogle Scholar
Liu, J. and Parkinson, J. S. (1989) Genetics and sequence analysis of the pcnB
locus, an Escherichia coli
gene involved in plasmid copy number control. J. Bacteriol.
, 1254–1261.PubMedGoogle Scholar
He, L., Söderbom, F., Wagner, G. H., Binnie, U., Binns, N. and Masters, M. (1993) PcnB is required for the rapid degradation of RNA I, the antisense RNA that controls the copy number of ColE1-related plasmids. Molec. Microbiol.
, 1131–1142.Google Scholar
Xu, F., Lin-Chao, S. and Cohen, S. N. (1993) The Escherichia coli pcnB
gene promotes adenylation of antisense RNAI of ColE1-type plasmids in vivo
and degradation of RNAI decay intermediates. Proc. Natl. Acad. Sci. USA
, 6756–6760.PubMedGoogle Scholar
Mohanty, B. K. and Kushner, S. R. (2000) Polynucleotide phosphorilase functions both as a 3′ right-arrow 5′ exonuclease and poly(A) polymerase in Escherichia coli
. Proc. Natl. Acad. Sci. USA
, 11966–11971.PubMedGoogle Scholar
Soberón, X., Covarrubias, L. and Bolívar, F. (1980) Construction and characterization of new cloning vehicles. IV. Deletion derivatives of pBR322 and pBR325. Gene
, 287–305.PubMedGoogle Scholar
Zurita, M., Bolívar, F. and Soberón, X. (1984) Construction and characterization of new cloning vehicles. VII. Construction of plasmid pBR327par, a completely sequenced, stable derivative of pBR327 containing the par locus of pSC101. Gene
, 119–122.PubMedGoogle Scholar
Vieira, J. and Messing, J. (1982) The pUC plasmids, an M13mp7-derived system for insertion mutagenesis and sequencing with synthetic universal primers. Gene
, 259–268.PubMedGoogle Scholar
Sozhamannan, S., Morris J. G. Jr., and Stitt, B. L. (1999) Instability of pUC19 in Escherichia coli
transcription termination factor mutant, rho026
, 63–69.PubMedGoogle Scholar
Atlung, T., Christensen, B. B., and Hansen, F. G. (1999) Role of the Rom protein in copy number control of plasmid pBR322 at diffrerent growth rates in Escherichia coli
, 110–119.PubMedGoogle Scholar
Lin-Chao, S., Chen, W. T., and Wong, T. T. (1992) High copy number of the pUC plasmids results from a Rom/Rop-supressible point mutation in RNA II. Mol. Microbiol.
, 3385–3393.PubMedGoogle Scholar
Malki, A., Kern, R., Kohiyama, M., and Huges, P. (1992) Inhibition of DNA synthesis at the hemimethylated pBR322 origin of replication by a cell membrane function. Nucleic Acids Res.
, 105–109.PubMedGoogle Scholar
Russell, D. W. and Zinder, N. D. (1987) Hemimethylation prevents DNA replication in E. coli
, 1071–1079.PubMedGoogle Scholar
Patnaik, P. K., Merlin, S. and Polisky, B. (1990) Effect of altering GATC sequences in the plasmid ColE1 primer promoter. J. Bacteriol.
, 1762–1764.PubMedGoogle Scholar
McDermott, P. J., Gowland, P., and Gowland, P. C. (1993) Adaptation of Escherichia coli
growth rates to the presence of pBR322. Lett. Appl. Microbiol.
, 139–143.PubMedGoogle Scholar
Paulson, J. and Ehrenberg, M. (1998) Trade-off between segregational stability and metabolic burden: a mathematical model of plasmid ColE1 replication control. J. Mol. Biol.
, 73–88.Google Scholar
Eisenbraun, M. D. and Griffith, J. K. (1993) Effects of plasmid pBR322 on respiratory and ATPase activities in Escherichia coli
, 159–162.PubMedGoogle Scholar
Bremer, H. and Lin-Chao, S. (1986) Analysis of the physiological control of replication of ColE1-type plasmids. J. Theor. Biol.
, 453–470.PubMedGoogle Scholar
Weber, A. E. and San, K. Y. (1987) Persistence and expression of the plasmid pBR322 in Eschericha coli
K-12 cultured in complex medium. Biotechnol. Lett.
, 757–760.Google Scholar
Duttweiler, H. M. and Gross, D. S. (1998) Bacterial growth medium that significantly increases the yield of recombinant plasmid. Biotechniques
, 438–444.PubMedGoogle Scholar
Lin-Chao, S. and Bremer, H. (1986) Effect of the bacterial growth rate on replication control of plasmid pBR322 in Escherichia coli
. Mol. Gen. Genet.
, 143–149.PubMedGoogle Scholar
Gasunov, V. V. and Brilkov, A. V. (2002) Estimating the instability parameters of plasmid-bearing cells. I. Chemostat culture. J. Theor. Biol.
, 193–205.Google Scholar
Herman, A., Wegrzyn, A., and Wegrzyn, G. (1994) Regulation of replication of plasmid pBR322 in amino acid-starved Escherichia coli
strains. Mol. Gen. Genet.
, 374–378.PubMedGoogle Scholar
Wrobel, B., and Wegrzyn, G. (1998) Replication regulation of ColE1-like plasmids in amino acid-starved Escherichia coli
, 48–62.PubMedGoogle Scholar
Wang, Z., Le, G., Shi, Y., Wegrzyn, G., and Wrobel, B. (2002) A model for regulation of ColE1-like plasmid replication by uncharged tRNAs in amino acid-starved Escherichia coli
, 69–78.PubMedGoogle Scholar
Kim, B. G., Good, T. A., Ataai, M. M., and Shuler, M. L. (1987) Growth behaviour and prediction of copy number and retention of ColE1-type plasmids in E. coli
under slow growth conditions. Ann. N.Y. Acad. Sci.
, 384–395.PubMedGoogle Scholar
Torkel-Nielsen, T. and Boe, L. (1994) A statistical analysis of the formation of plasmid-free cells in populations of Escherichia coli
. J. Bacteriol.
, 4306–4310.Google Scholar
Lee, S. B. and Bailey, J. E. (2002) Analysis of growth rate effects on productivity of recombinant Escherichia coli
populations using molecular mechanism models. Biotechnol. Bioeng.
, 550–557.PubMedGoogle Scholar
Weston-Hafer, K. and Berg, D. E. (1991) Deletions in plasmid pBR322: replication slippage involving leading and lagging strands. Genetics
, 487.Google Scholar
Vilette, D., Ehrlich, S. D. and Michel, B. (1995) Transcription-induced deletions in Escherichia coli
plasmids. Mol. Microbiol.
, 493–504.PubMedGoogle Scholar
Olavarrieta, L., Hernández, P., Krimer, D. B., and Schvartzman, J. B. (2002) DNA knotting caused by head-on collision of transcription and replication. J. Mol. Biol.
, 1–6.PubMedGoogle Scholar
Sogo, J. M., Stasiak, A., Martínez-Robles, M. L., Krimer, D. B., Hernández, P., and Schvartzman, J. B. (1999) Formation of knots in partially replicated DNA molecules. J. Mol. Biol.
, 637–643.PubMedGoogle Scholar
Benham, C. J. (1993) Sites of predicted stress-induced DNA duplex destabilization occur preferentially at regulatory loci. Proc. Natl. Acad. Sci. USA
, 2999–3003.PubMedGoogle Scholar
Frenkel, L. and Bremer, H. (1986). Incresased concentration of plasmid pBR322 and pBR327 by low concentrations of chloramphenicol. DNA
, 539–544.PubMedGoogle Scholar
Schroetel, A., Riethdorf, S. and Hecker, M. (1988) Amplification of different ColE1 plasmids in Escherichia coli relA
strain. J. Basic Microbiol.
, 553–555.Google Scholar
Riethdorf, S., Schroeter, A., and Hecker, M. (1989) RelA mutation and pBR322 plasmid amplification in amino acid-starved cells of Escherichia coli
. Genet. Res.
, 167–171.PubMedGoogle Scholar
Hofmann, K. H., Neubauer, P., Riethdorf, S., and Hecker, M. (1990) Amplification of pBR322 plasmid DNA in Escherichia coli relA
strains during batch and fed-batch fermentation. J. Basic. Microbiol.
, 37–41.PubMedGoogle Scholar
Wolfson, J. S., Hooper, D. C., Swartz, M. N., and McHugh, G. L. (1982) Antagonism of the B subunit of DNA gyrase eliminates plasmids pBR322 and pMG110 from Escherichia coli
. J. Bacteriol.
, 338–344.PubMedGoogle Scholar
Ishii, S., Murakami, T. and Shishido, K. (1991) Gyrase inhibitors increase the content of knotted DNA species of plasmid pBR322 in Escherichia coli
. J. Bacteriol.
, 5551–5553.PubMedGoogle Scholar
Lakshmi, V. V. and Polasa, H. (1991) Curing of pBR322 and pBR329 plasmids in Escherichia coli
by cis-dichlorodiamine platinum (II) chloride (Cis-DDP). FEMS Microbiol. Lett.
, 281–284.PubMedGoogle Scholar
Lakshmi, V. V., Sridhar, P., Khan, B. T., and Polasa, H. (1988) Mixed-ligand complexes of platinum (II) as curing agents for pBR322 and pBR329 (ColE1) plasmids in Escherichia coli
. J. Gen. Microbiol.
, 1977–1981.PubMedGoogle Scholar
Brahati, A. and Polasa, H. (1990) Elimination of ColE1 group (pBR322 and pBR329) plasmids in Escherichia coli
by alpha-satonin. FEMS Microbiol. Lett.
, 213–215.Google Scholar
Watson, N. (1988) A new revision of the sequence of plasmid pBR322. Gene
, 399–403.PubMedGoogle Scholar
Valenzuela, M. S., Ikpeazu, E. V. and Siddiqui, K. A. (1996) E. coli
growth inhibition by high copy number derivative of plasmid pBR322. Biochem. Biophys. Res. Commun.
, 219.Google Scholar
Magee, T. R. and Kogoma, T. (1991) Rifampin-resistant replication of pBR322 derivatives in Escherichia coli
cells induced for the SOS response. J. Bacteriol.
, 4736–4741.PubMedGoogle Scholar
Parada, C. A. and Marians, K. J. (1991) Mechanism of DNA A protein-dependent pBR322 DNA replication. DNA A-mediated trans-strand loading of the DNA B protein at the origin of pBR322 DNA. J. Biol. Chem.
, 18895–18906.PubMedGoogle Scholar
Silberstein, Z. and Cohen, A. (1987) Synthesis of linear multimers of oriC
and pBR322 derivatives in Escherichia coli
K-12: role of recombination and replication functions. J. Bacteriol.
, 3131–3137.PubMedGoogle Scholar
Petersen, S. K. and Hansen, F. G. (1991) A missense mutation in the rpoC
gene affects chromosomal replication control in E. coli
. J. Bacteriol.
, 5200–5206.PubMedGoogle Scholar
McNicholas, P., Chopra, I., and Rothstein, D. M. (1992) Genetic analysis of the tetA(C) gene on plasmid pBR322. J. Bacteriol.
, 7926–7933.PubMedGoogle Scholar
Shishido, K., Ishii, S., and Komiyama, N. (1989) The presence of the region on pBR322 that encodes resistance to tetracycline is responsible for high levels of plasmid knotting in Escherichia coli
DNA topoisomerase mutant. Nucleic Acids Res.
, 9749–9759.PubMedGoogle Scholar
Allard, J. D. and Bertrand, K. P. (1992) Membrane topology of the pBR322 tetracycline resistance protein. J. Biol. Chem.
, 17809–17819.PubMedGoogle Scholar
Lewis, G. S., Jewel, J. E., Phang, T. and Miller, K. W. (2002) Mutational analysis of tetracycline resistance protein transmembrane segment insertion. Arch. Biochem. Biophys.
, 317–325.PubMedGoogle Scholar
McNicholas, P., McGlynn, M., Guay, G. G. and Rothstein, D. M. (1995) Genetic analysis suggests functional interactions between the N-and C-terminal domains of the TetA(C) efflux pump encoded by pBR322. J. Bacteriol.
, 5355–5357.PubMedGoogle Scholar
Valenzuela, M. S., Siddiqui, K. A. and Sarkar, B. L. (1996) High expression of plasmid-encoded tetracycline resistance gene in E. coli
causes a decrease in membrane-bound ATPase activity. Plasmid
, 19–25.PubMedGoogle Scholar
Chiang, C. S. and Bremer, H. (1988) Stability of pBR322-derived plasmids. Plasmid.
, 207–220.PubMedGoogle Scholar
Pruss, G. J. and Drlica, K. (1986) Topoisomerase I mutants: the gene on pBR322 that encodes resistance to tetracycline affects plasmid DNA supercoiling. Proc. Natl. Acad. Sci. USA
, 8952–8956.PubMedGoogle Scholar
Lodge, J. K., Kazic, T., and Berg, D. E. (1989) Formation of supercoiling domains in plasmid pBR322. J. Bacteriol.
, 2181–2187.PubMedGoogle Scholar
Griffith, J. K., Cuellar, D. H., Fordyce, C. A., Hutchings, K. G., and Mondragón, A. A. (1994) Structure and function of the class C tetracycline/H+ antiporter: three dependent groups of phenotypes are conferred by TetA (C). Mol. Membr. Biol.
, 271–277.PubMedGoogle Scholar
Stavropoulous, T. A. and Strathdee, C. A. (2000) Expression of the TetA (C) tetracycline efflux pump in Escherichia coli
confers osmotic sensitivity. FEMS Microbiol. Lett.
, 147–150.Google Scholar
Katayama, T. and Nagata, T. (1990) Inhibition of cell growth and stable DNA replication by overexpression of the bla
gene of plasmid pBR322 in Escherichia coli
. Molec. Gen. Genet.
, 353–360.PubMedGoogle Scholar
Kuriki, Y. (1987) Requirement of a heat-labile factor(s) for in vivo expression of the amp
gene of pBR322. J. Bacteriol.
, 5856–5858.PubMedGoogle Scholar
Berg, C. M., Liu, L., Coon, M., Gray, P., Vartak, N. B., Brown, M., et al. (1989) pBR322-derived multicopy plasmids harboring large inserts are often dimmers in Escherichia coli
, 138–141.PubMedGoogle Scholar
Boyd, L. A., Woytowich, A. and Selvaraj, G. (1993) Target sequence specificity of transposon Tn
5 in the absence of major hotspots in the plasmid pBR322: identification of a new hotspot. Plasmid
, 155–158.PubMedGoogle Scholar
Lodge, J. K, and Berg, D. E. (1990) Mutations that affect Tn
5 insertion into pBR322: importance of local supercoiling. J. Bacteriol.
, 5956–5960.PubMedGoogle Scholar
Gamas, P., Chandler, M. G., Prentki, P., and Galas, D. J. (1987) Escherichia coli
integration host factor binds specifically to the ends of the insertion sequence IS
1 and to its major insertion hotspot in pBR322. J. Mol. Biol.
, 261–272.PubMedGoogle Scholar
Hogget, J. G. and Brierley, I. (1992) Kinetics of activation of the P4 promoter by Escherichia coli
cyclic AMP receptor protein. Biochem. J.
, 937–941.Google Scholar
Brierley, I. and Hogget, J. G. (1992) Binding of the cyclic AMP receptor protein of Escherichia coli
and DNA bending at the P4 promoter of pBR322. Biochem. J.
, 91–97.PubMedGoogle Scholar
Zhang, P. and Omaye, S. T. (2001) DNA strand breakage and oxygen tension: effects of beta-carotene, alpha-tocopherol and ascorbic acid. Food Chem. Toxicol.
, 239–246.PubMedGoogle Scholar
Rajagopalan, R., Wani, K., Huilgol, N. G., Kagiya, T. V., and Nair, C. K. (2002) Inhibition of gamma-radiation induced DNA damage in plasmid pBR322 by TMG, a water soluble derivative of vitamin E. J. Radiat. Res.
, 153–159.PubMedGoogle Scholar
Melchior, W. B., Jr., Marques, M. M. and Beland, F. A. (1994) Mutations induced by aromatic amine DNA adducts in pBR322. Carcinogenesis
, 889–899.PubMedGoogle Scholar
Kumar, S. S., Chaubey, R. C., Devasagayam, T. P., Priyadarsini, K. I., and Chauhan, P. S. (1999) Inhibition of radiation-induced DNA damage in plasmid pBR322 by chlorophyllin and possible mechanism(s) of action. Mutat Res.
, 71–79.PubMedGoogle Scholar
Kumar, S. S., Devasagayan, T. P., Jayashree, B. and Kesavan, P. C. (2001) Mechanism of protection against radiation-induced DNA damage in plasmid pBR322 by caffeine. Int. J. Radiat. Biol.
, 617–623.PubMedGoogle Scholar
Lourencini da Silva, R., Albano, F., Lopes do Santos, L. R., Tavares, A. D. Jr., and Felzenszwall, I. (2000) The effect of electromagnetic field exposure on the formation of DNA lesions. Redox Rep.
, 299–301.Google Scholar
Levi, B. and Werman, M. J. (2001) Fructose triggers DNA modifications and damage in an Escherichia coli
plasmid. J. Nutr. Biochem.
, 235–241.PubMedGoogle Scholar
Vanella, A., Russo, A., Acquaviva, R., Campisi, A., Di Giacomo, C., Sorrenti V. et al. (2000) L-propionyl-carnitine as superoxide scavenger, antioxidant, and DNA cleavage protector. Cell. Biol. Toxicol.
, 99–104PubMedGoogle Scholar
Adam, W., Hartung, J., Okamoto, H., Saha-Moller, C. R., and Spehar, K. (2000) N-hydroxy-4-(4-chlorophenyl)thiazole-2(3H)-thione as a photochemical hydroxyl-radical source: photochemistry and oxidative damage of DNA (strand breaks) and 2′-deoxyguanosine (8-oxodG formation). Photochem Photobiol.
, 619–64.PubMedGoogle Scholar
Onoa, G. B. and Moreno, V. (2002) Study of the modifications caused by cisplatin, transplatin, and Pd(II) and Pt(II) mepirizole derivatives on pBR322 DNA by atomic force microscopy. Int. J. Pharm.
, 55–65.PubMedGoogle Scholar
Balbás, P. and Gosset, G. (2001) Chromosomal editing in Escherichia coli
: vectors for DNA integration and excision. Mol. Biotechnol.
, 1–12.PubMedGoogle Scholar
Balbás, P. and Bolivar, F. (1998) Molecular cloning by plasmid vectors. in Recombinant DNA
. Principles and Applications (Greene, J. J. and Rao, V. B. eds.), Marcel Dekker, Inc., New York, NY, pp. 383–411.Google Scholar
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