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. 1994 Aug;176(16):4931–4936. doi: 10.1128/jb.176.16.4931-4936.1994

Second-site suppressors of the bacteriophage P1 virs mutant reveal the interdependence of the c4, icd, and ant genes in the P1 immI operon.

J Heinrich 1, M Citron 1, A Günther 1, H Schuster 1
PMCID: PMC196329  PMID: 8051007

Abstract

The immI operon of phage P1 contains the genes c4, icd, and ant, which are transcribed in that order from the same constitutive promoter, P51b. The gene c4 encodes an antisense RNA which inhibits the synthesis of an antirepressor by acting on a target ant mRNA. Interaction depends on the complementarity of two pairs of short sequences encompassing virs+ and the ribosome-binding site involved in ant expression. Accordingly, in a P1 virs mutant phage, antirepressor is synthesized constitutively. We have isolated lysogen-proficient, second-site suppressors of P1 virs in order to evaluate the interdependence of the immI-specific genes. From a total of 17 suppressors analyzed, 15 were found to be located in the icd gene. They were identified as frameshift mutations, containing base insertions or deletions in tandem repeats of a single base pair. One suppressor was identified as a P51b promoter-down mutation; the second site of another suppressor was found to be located in the c4 gene. Furthermore, it was shown that virs cannot be suppressed by ant (icd+) suppressors. The results confirm the model that the immI operon is transcribed as a unit, that the icd and ant genes are translationally coupled, and that the constitutive synthesis of Icd protein alone is lethal to the bacterial cell. The existence of a c4 suppressor of virs, whose effect is not yet known, points to a still more complex regulation of antirepressor synthesis than was anticipated from the model.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Baumstark B. R., Stovall S. R., Ashkar S. Interaction of the P1c1 repressor with P1 DNA: localization of repressor binding sites near the c1 gene. Virology. 1987 Feb;156(2):404–413. doi: 10.1016/0042-6822(87)90420-x. [DOI] [PubMed] [Google Scholar]
  2. Baumstark B. R., Stovall S. R., Bralley P. The ImmC region of phage P1 codes for a gene whose product promotes lytic growth. Virology. 1990 Nov;179(1):217–227. doi: 10.1016/0042-6822(90)90291-x. [DOI] [PubMed] [Google Scholar]
  3. Benzer S. ON THE TOPOGRAPHY OF THE GENETIC FINE STRUCTURE. Proc Natl Acad Sci U S A. 1961 Mar;47(3):403–415. doi: 10.1073/pnas.47.3.403. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Biere A. L., Citron M., Schuster H. Transcriptional control via translational repression by c4 antisense RNA of bacteriophages P1 and P7. Genes Dev. 1992 Dec;6(12A):2409–2416. doi: 10.1101/gad.6.12a.2409. [DOI] [PubMed] [Google Scholar]
  5. Chen E. Y., Seeburg P. H. Supercoil sequencing: a fast and simple method for sequencing plasmid DNA. DNA. 1985 Apr;4(2):165–170. doi: 10.1089/dna.1985.4.165. [DOI] [PubMed] [Google Scholar]
  6. Citron M., Schuster H. The c4 repressor of bacteriophage P1 is a processed 77 base antisense RNA. Nucleic Acids Res. 1992 Jun 25;20(12):3085–3090. doi: 10.1093/nar/20.12.3085. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Citron M., Schuster H. The c4 repressors of bacteriophages P1 and P7 are antisense RNAs. Cell. 1990 Aug 10;62(3):591–598. doi: 10.1016/0092-8674(90)90023-8. [DOI] [PubMed] [Google Scholar]
  8. Citron M., Velleman M., Schuster H. Three additional operators, Op21, Op68, and Op88, of bacteriophage P1. Evidence for control of the P1 dam methylase by Op68. J Biol Chem. 1989 Feb 25;264(6):3611–3617. [PubMed] [Google Scholar]
  9. Cohen G., Sternberg N. Genetic analysis of the lytic replicon of bacteriophage P1. I. Isolation and partial characterization. J Mol Biol. 1989 May 5;207(1):99–109. doi: 10.1016/0022-2836(89)90443-9. [DOI] [PubMed] [Google Scholar]
  10. Eliason J. L., Sternberg N. Characterization of the binding sites of c1 repressor of bacteriophage P1. Evidence for multiple asymmetric sites. J Mol Biol. 1987 Nov 20;198(2):281–293. doi: 10.1016/0022-2836(87)90313-5. [DOI] [PubMed] [Google Scholar]
  11. Heinzel T., Velleman M., Schuster H. C1 repressor of phage P1 is inactivated by noncovalent binding of P1 Coi protein. J Biol Chem. 1992 Feb 25;267(6):4183–4188. [PubMed] [Google Scholar]
  12. Heinzel T., Velleman M., Schuster H. The c1 repressor inactivator protein coi of bacteriophage P1. Cloning and expression of coi and its interference with c1 repressor function. J Biol Chem. 1990 Oct 15;265(29):17928–17934. [PubMed] [Google Scholar]
  13. Heisig A., Riedel H. D., Dobrinski B., Lurz R., Schuster H. Organization of the immunity region immI of bacteriophage P1 and synthesis of the P1 antirepressor. J Mol Biol. 1989 Oct 20;209(4):525–538. doi: 10.1016/0022-2836(89)90591-3. [DOI] [PubMed] [Google Scholar]
  14. Pribnow D., Sigurdson D. C., Gold L., Singer B. S., Napoli C., Brosius J., Dull T. J., Noller H. F. rII cistrons of bacteriophage T4. DNA sequence around the intercistronic divide and positions of genetic landmarks. J Mol Biol. 1981 Jul 5;149(3):337–376. doi: 10.1016/0022-2836(81)90477-0. [DOI] [PubMed] [Google Scholar]
  15. Riedel H. D., Heinrich J., Heisig A., Choli T., Schuster H. The antirepressor of phage P1. Isolation and interaction with the C1 repressor of P1 and P7. FEBS Lett. 1993 Nov 15;334(2):165–169. doi: 10.1016/0014-5793(93)81705-5. [DOI] [PubMed] [Google Scholar]
  16. Riedel H. D., Heinrich J., Schuster H. Cloning, expression, and characterization of the icd gene in the immI operon of bacteriophage P1. J Bacteriol. 1993 May;175(10):2833–2838. doi: 10.1128/jb.175.10.2833-2838.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Schaefer T. S., Hays J. B. The bof gene of bacteriophage P1: DNA sequence and evidence for roles in regulation of phage c1 and ref genes. J Bacteriol. 1990 Jun;172(6):3269–3277. doi: 10.1128/jb.172.6.3269-3277.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Scott J. R., West B. W., Laping J. L. Superinfection immunity and prophage repression in phage P1. IV. The c1 repressor bypass function and the role of c4 repressor in immunity. Virology. 1978 Apr;85(2):587–600. doi: 10.1016/0042-6822(78)90463-4. [DOI] [PubMed] [Google Scholar]
  20. Shine J., Dalgarno L. Determinant of cistron specificity in bacterial ribosomes. Nature. 1975 Mar 6;254(5495):34–38. doi: 10.1038/254034a0. [DOI] [PubMed] [Google Scholar]
  21. Sternberg N. A characterization of bacteriophage P1 DNA fragments cloned in a lambda vector. Virology. 1979 Jul 15;96(1):129–142. doi: 10.1016/0042-6822(79)90179-x. [DOI] [PubMed] [Google Scholar]
  22. Velleman M., Dreiseikelmann B., Schuster H. Multiple repressor binding sites in the genome of bacteriophage P1. Proc Natl Acad Sci U S A. 1987 Aug;84(16):5570–5574. doi: 10.1073/pnas.84.16.5570. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Velleman M., Heinzel T., Schuster H. The Bof protein of bacteriophage P1 exerts its modulating function by formation of a ternary complex with operator DNA and C1 repressor. J Biol Chem. 1992 Jun 15;267(17):12174–12181. [PubMed] [Google Scholar]
  24. Velleman M., Heirich M., Günther A., Schuster H. A bacteriophage P1-encoded modulator protein affects the P1 c1 repression system. J Biol Chem. 1990 Oct 25;265(30):18511–18517. [PubMed] [Google Scholar]
  25. Walker D. H., Jr, Walker J. T. Genetic studies of coliphage P1. I. Mapping by use of prophage deletions. J Virol. 1975 Sep;16(3):525–534. doi: 10.1128/jvi.16.3.525-534.1975. [DOI] [PMC free article] [PubMed] [Google Scholar]

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