Summary
Multicopy plasmids carrying the sopB gene of the F plasmid inhibit stable inheritance of a coexisting mini-F plasmid. This incompatibility, termed IncG, is found to be caused by excess amounts of the SopB protein, which is essential for accuratepartitioning of plasmid DNA molecules into daughter cells. A sopB-carrying multicopy plasmid that shows the IncG+ phenotype was mutagenized in vitro and IncG negative mutant plasmids were isolated. Among these amber and missense mutants of sopB, mutants with a low plasmid copy number and a mutant in the Shine-Dalgarno sequence for translation of the SopB protein were obtained. These results demonstrate that the IncG phenotype is caused by the SopB protein, and that the incompatibility is expressed only when the protein is overproduced. This suggests that the protein must be kept at appropriate concentrations to ensure stable maintenance of the plasmid.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Adler HI, Fisher WD, Cohen A, Hardigree AA (1967) Miniature Escherichia coli cells deficient in DNA. Proc Natl Acad Sci USA 57:321–326
Austin S, Wiezbecki A (1983) Two mini-F encoded proteins are essential for equipartitioning. Plasmid 10:73–81
Christen AA, Pall ML, Manzara T, Lurquin PF (1983) Rapid isolation of Escherichia coli minicells by glass-fiber filtration: study of plasmid-encoded polypeptides. Gene 23:195–198
Gardner RC, Malcolm L, Bergquist PL, Lane HED (1982) IncD, a genetic locus in F responsible for incompatibility with several plasmids of the IncFI group. Mol Gen Genet 188:345–352
Hanahan D (1983) Studies on transformation of Escherichia coli with plasmids. J Mol Biol 166:557–580
Hayakawa Y, Murotsu T, Matsubara K (1985) Mini-F protein that binds to a unique region for partition of mini-F plasmid DNA. J Bacteriol 163:349–354
Helsberg M, Eichenlaub R (1986) Twelve 43-base-pair repeats map in a cis-acting region essential for partition of plasmid mini-F. J Bacteriol 165:1043–1045
Hiraga S, Jaffé A, Ogura T, Mori H, Takahashi H (1986) F plasmid ccd mechanism in Escherichia coli. J Bacteriol 166:100–104
Hiraga S, Ogura T, Mori H, Tanaka M (1985) Mechanisms essential for stable inheritance of mini-F plasmid. In: Helinski DR, Cohen SN, Clewell DB, Jackson DA, Hollaender A (eds) Plasmids in bacteria. Plenum, New York, pp 469–478
Humphreys GO, Willshaw GA, Smith HR, Anderson ES (1976) Mutagenesis of plasmid DNA with hydroxylamine: isolation of mutants of multi-copy plasmids. Mol Gen Genet 145:101–108
Jaffé A, Ogura T, Hiraga S (1985) Effects of the ccd function of the F plasmid on bacterial growth. J Bacteriol 163:841–849
Komai N, Nishizawa T, Hayakawa Y, Murotsu T, Matsubara K (1982) Detection and mapping of six mini F-encoding proteins by cloning analysis of dissected mini F segments. Mol Gen Genet 186:193–203
Laemmli UK (1970) Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature 227:680–685
Maniatis T, Fritsch EF, Sambrook J (1982) Molecular cloning. A laboratory manual. Cold Spring Harbor Laboratory, New York
Messing J, Crea R, Seeburg PH (1981) A system for shotgun DNA sequencing. Nucleic Acids Res 9:309–321
Miller JH (1972) Experiments in molecular genetics. Cold Spring Harbor Laboratory, New York
Mori H, Kondo A, Ohshima A, Ogura T, Hiraga S (1986) Structure and function of the F plasmid genes essential for partitioning. J Mol Biol 192:1–15
Murotsu T, Matsubara K, Sugisaki H, Takanami M (1981) Nine unique repeating sequences in a region essential for replication and incompatibility of the mini-F plasmid. Gene 15:257–271
Ogura T, Hiraga S (1983a) Parition mechanism of F plasmid: two plasmid gene-encoded products and a cis-acting region are involved in partition. Cell 32:351–360
Ogura T, Hiraga S (1983b) Mini-F plasmid genes that couple host cell division to plasmid proliferation. Proc Natl Acad Sci USA 80:4784–4788
Ogura T, Miki T, Hiraga S (1980) Copy-number mutants of the plasmid carrying the replication origin of the Escherichia coli chromosome: evidence for a control region of replication. Proc Natl Acad Sci USA 77:3993–3997
Tolun A, Helinski DR (1981) Direct repeats of the F plasmid incC region expresses F incompatibility. Cell 24:687–694
Wehlmann H, Eichenlaub R (1980) Plasmid mini-F encoded proteins. Mol Gen Genet 180:205–211
Author information
Authors and Affiliations
Additional information
Communicated by K. Isono
Rights and permissions
About this article
Cite this article
Kusukawa, N., Mori, H., Kondo, A. et al. Partitioning of the F plasmid: Overproduction of an essential protein for partition inhibits plasmid maintenance. Mol Gen Genet 208, 365–372 (1987). https://doi.org/10.1007/BF00328125
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00328125