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. 1995 Jul;177(14):3940–3945. doi: 10.1128/jb.177.14.3940-3945.1995

The mobilization regions of two integrated Bacteroides elements, NBU1 and NBU2, have only a single mobilization protein and may be on a cassette.

L Y Li 1, N B Shoemaker 1, G R Wang 1, S P Cole 1, M K Hashimoto 1, J Wang 1, A A Salyers 1
PMCID: PMC177121  PMID: 7608064

Abstract

Bacteroides conjugative transposons can act in trans to excise, circularize, and transfer unlinked integrated elements called NBUs (for nonreplicating Bacteroides units). Previously, we localized and sequenced the mobilization region of one NBU, NBU1, and showed that this mobilization region was recognized by the IncP plasmids RP4 and R751, as well as by the Bacteroides conjugative transposons. We report here that the single mobilization protein carried by NBU1 appears to be a bifunctional protein that binds to the oriT region and catalyzes the nicking reaction that initiates the transfer process. We have also localized and sequenced the mobilization region of a second NBU, NBU2. The NBU2 mobilization region was 86 to 90% identical at the DNA sequence to the oriT-mob region of NBU1. The high sequence similarity between NBU1 and NBU2 ended abruptly after the stop codon of the mob gene and about 1 kbp upstream of the oriT region, indicating that the oriT-mob regions of NBU1 and NBU2 may be on some sort of cassette. A region on NBU1 and NBU2 which lies immediately upstream of the oriT region had 66% sequence identity to a region upstream of the oriT region on a mobilizable transposon, Tn4399, an element that had previously appeared to be completely unrelated to the NBUs.

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Selected References

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  1. Balzer D., Pansegrau W., Lanka E. Essential motifs of relaxase (TraI) and TraG proteins involved in conjugative transfer of plasmid RP4. J Bacteriol. 1994 Jul;176(14):4285–4295. doi: 10.1128/jb.176.14.4285-4295.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Bedzyk L. A., Shoemaker N. B., Young K. E., Salyers A. A. Insertion and excision of Bacteroides conjugative chromosomal elements. J Bacteriol. 1992 Jan;174(1):166–172. doi: 10.1128/jb.174.1.166-172.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Guiney D. G., Helinski D. R. The DNA-protein relaxation complex of the plasmid RK2: location of the site-specific nick in the region of the proposed origin of transfer. Mol Gen Genet. 1979 Oct 3;176(2):183–189. doi: 10.1007/BF00273212. [DOI] [PubMed] [Google Scholar]
  4. Hecht D. W., Malamy M. H. Tn4399, a conjugal mobilizing transposon of Bacteroides fragilis. J Bacteriol. 1989 Jul;171(7):3603–3608. doi: 10.1128/jb.171.7.3603-3608.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Hecht D. W., Thompson J. S., Malamy M. H. Characterization of the termini and transposition products of Tn4399, a conjugal mobilizing transposon of Bacteroides fragilis. Proc Natl Acad Sci U S A. 1989 Jul;86(14):5340–5344. doi: 10.1073/pnas.86.14.5340. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Li L. Y., Shoemaker N. B., Salyers A. A. Characterization of the mobilization region of a Bacteroides insertion element (NBU1) that is excised and transferred by Bacteroides conjugative transposons. J Bacteriol. 1993 Oct;175(20):6588–6598. doi: 10.1128/jb.175.20.6588-6598.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Murphy C. G., Malamy M. H. Characterization of a "mobilization cassette" in transposon Tn4399 from Bacteroides fragilis. J Bacteriol. 1993 Sep;175(18):5814–5823. doi: 10.1128/jb.175.18.5814-5823.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Pansegrau W., Lanka E. Common sequence motifs in DNA relaxases and nick regions from a variety of DNA transfer systems. Nucleic Acids Res. 1991 Jun 25;19(12):3455–3455. doi: 10.1093/nar/19.12.3455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Pansegrau W., Ziegelin G., Lanka E. The origin of conjugative IncP plasmid transfer: interaction with plasmid-encoded products and the nucleotide sequence at the relaxation site. Biochim Biophys Acta. 1988 Dec 20;951(2-3):365–374. doi: 10.1016/0167-4781(88)90108-x. [DOI] [PubMed] [Google Scholar]
  10. Shoemaker N. B., Barber R. D., Salyers A. A. Cloning and characterization of a Bacteroides conjugal tetracycline-erythromycin resistance element by using a shuttle cosmid vector. J Bacteriol. 1989 Mar;171(3):1294–1302. doi: 10.1128/jb.171.3.1294-1302.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Shoemaker N. B., Salyers A. A. Tetracycline-dependent appearance of plasmidlike forms in Bacteroides uniformis 0061 mediated by conjugal Bacteroides tetracycline resistance elements. J Bacteriol. 1988 Apr;170(4):1651–1657. doi: 10.1128/jb.170.4.1651-1657.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Shoemaker N. B., Wang G. R., Stevens A. M., Salyers A. A. Excision, transfer, and integration of NBU1, a mobilizable site-selective insertion element. J Bacteriol. 1993 Oct;175(20):6578–6587. doi: 10.1128/jb.175.20.6578-6587.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Smith C. J., Parker A. C. Identification of a circular intermediate in the transfer and transposition of Tn4555, a mobilizable transposon from Bacteroides spp. J Bacteriol. 1993 May;175(9):2682–2691. doi: 10.1128/jb.175.9.2682-2691.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Stevens A. M., Sanders J. M., Shoemaker N. B., Salyers A. A. Genes involved in production of plasmidlike forms by a Bacteroides conjugal chromosomal element share amino acid homology with two-component regulatory systems. J Bacteriol. 1992 May;174(9):2935–2942. doi: 10.1128/jb.174.9.2935-2942.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Valentine P. J., Shoemaker N. B., Salyers A. A. Mobilization of Bacteroides plasmids by Bacteroides conjugal elements. J Bacteriol. 1988 Mar;170(3):1319–1324. doi: 10.1128/jb.170.3.1319-1324.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]

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