This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Franco, A. A. Articles by Sears, C. L. Search for Related Content PubMed PubMed Citation Articles by Franco, A. A. Articles by Sears, C. L.

 Previous Article  |  Next Article 

Infect. Immun., Mar 1997, 1007-1013, Vol 65, No. 3
Copyright © 1997, American Society for Microbiology

Cloning and characterization of the Bacteroides fragilis metalloprotease toxin gene

AA Franco, LM Mundy, M Trucksis, S Wu, JB Kaper and CL Sears
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.

Strains of Bacteroides fragilis that produce a ca. 20-kDa heat-labile protein toxin (termed B. fragilis toxin [BFT]) have been associated with diarrheal disease of animals and humans. BFT alters the morphology of intestinal epithelial cells both in vitro and in vivo and stimulates secretion in ligated intestinal segments of rats, rabbits, and lambs. Previous genetic and biochemical data indicated that BFT was a metalloprotease which hydrolyzed G (monomeric) actin, gelatin, and azocoll in vitro. In this paper, the cloning and sequencing of the entire B. fragilis toxin gene (bft) from enterotoxigenic B. fragilis (ETBF) 86-5443-2-2 is reported. The bft gene from this ETBF strain consists of one open reading frame of 1,191 nucleotides encoding a predicted 397-residue holotoxin with a calculated molecular weight of 44,493. Comparison of the predicted BFT protein sequence with the N- terminal amino acid sequence of purified BFT indicates that BFT is most probably synthesized by ETBF strains as a preproprotein. These data predict that BFT is processed to yield a biologically active toxin of 186 residues with a molecular mass of 20.7 kDa which is secreted into the culture supernatant. Analysis of the holotoxin sequence predicts a 20-residue amphipathic region at the carboxy terminus of BFT. Thus, in addition to the metalloprotease activity of BFT, the prediction of an amphipathic domain suggests that oligomerization of BFT may permit membrane insertion of the toxin with creation of a transmembrane pore. Comparison of the sequences available for the bft genes from ETBF 86- 5443-2-2 and VPI 13784 revealed two regions of reduced homology. Hybridization of oligonucleotide probes specific for each bft to toxigenic B.fragilis strains revealed that 51 and 49% of toxigenic strains contained the 86-5433-2-2 and VPI 13784 bft genes, respectively. No toxigenic strain hybridized with both probes. We propose that these two subtypes of bft be termed bft-1 (VPI 13784) and bft-2 (86-5433-2-2).

This article has been cited by other articles:

• Terhes, G., Brazier, J. S., Soki, J., Urban, E., Nagy, E. (2007). Coincidence of bft and cfiA genes in a multi-resistant clinical isolate of Bacteroides fragilis. J Med Microbiol 56: 1416-1418 [Full Text]  
• Buckwold, S. L., Shoemaker, N. B., Sears, C. L., Franco, A. A. (2007). Identification and Characterization of Conjugative Transposons CTn86 and CTn9343 in Bacteroides fragilis Strains. Appl. Environ. Microbiol. 73: 53-63 [Abstract] [Full Text]  
• Greenlee, K. J., Werb, Z., Kheradmand, F. (2007). Matrix Metalloproteinases in Lung: Multiple, Multifarious, and Multifaceted. Physiol. Rev. 87: 69-98 [Abstract] [Full Text]  
• Sears, C. L., Buckwold, S. L., Shin, J. W., Franco, A. A. (2006). The C-Terminal Region of Bacteroides fragilis Toxin Is Essential to Its Biological Activity.. Infect. Immun. 74: 5595-5601 [Abstract] [Full Text]  
• Franco, A. A., Buckwold, S. L., Shin, J. W., Ascon, M., Sears, C. L. (2005). Mutation of the Zinc-Binding Metalloprotease Motif Affects Bacteroides fragilis Toxin Activity but Does Not Affect Propeptide Processing. Infect. Immun. 73: 5273-5277 [Abstract] [Full Text]  
• Franco, A. A. (2004). The Bacteroides fragilis Pathogenicity Island Is Contained in a Putative Novel Conjugative Transposon. J. Bacteriol. 186: 6077-6092 [Abstract] [Full Text]  
• Wu, S., Dreyfus, L. A., Tzianabos, A. O., Hayashi, C., Sears, C. L. (2002). Diversity of the Metalloprotease Toxin Produced by Enterotoxigenic Bacteroides fragilis. Infect. Immun. 70: 2463-2471 [Abstract] [Full Text]  
• Sandini, S., d'Abusco, A. S., La Valle, R., Pantosti, A. (2001). Production of a Mouse Antiserum to Bacteroides fragilis Enterotoxin Using a Recombinant Enterotoxin Precursor. CVI 8: 190-191 [Abstract] [Full Text]  
• Gutacker, M., Valsangiacomo, C., Piffaretti, J.-C. (2000). Identification of two genetic groups in Bacteroides fragilis by multilocus enzyme electrophoresis: distribution of antibiotic resistance (cfiA, cepA) and enterotoxin (bft) encoding genes. Microbiology 146: 1241-1254 [Abstract] [Full Text]  
• d'Abusco, A. S., Del Grosso, M., Censini, S., Covacci, A., Pantosti, A. (2000). The Alleles of the bft Gene Are Distributed Differently among Enterotoxigenic Bacteroides fragilis Strains from Human Sources and Can Be Present in Double Copies. J. Clin. Microbiol. 38: 607-612 [Abstract] [Full Text]  
• Franco, A. A., Cheng, R. K., Chung, G.-T., Wu, S., Oh, H.-B., Sears, C. L. (1999). Molecular Evolution of the Pathogenicity Island of Enterotoxigenic Bacteroides fragilis Strains. J. Bacteriol. 181: 6623-6633 [Abstract] [Full Text]  
• Chung, G.-T., Franco, A. A., Wu, S., Rhie, G.-E., Cheng, R., Oh, H.-B., Sears, C. L. (1999). Identification of a Third Metalloprotease Toxin Gene in Extraintestinal Isolates of Bacteroides fragilis. Infect. Immun. 67: 4945-4949 [Abstract] [Full Text]  
• Riegler, M, Lotz, M, Sears, C, Pothoulakis, C, Castagliuolo, I, Wang, C C, Sedivy, R, Sogukoglu, T, Cosentini, E, Bischof, G, Feil, W, Teleky, B, Hamilton, G, LaMont, J T, Wenzl, E (1999). Bacteroides fragilis toxin 2 damages human colonic mucosa in vitro. Gut 44: 504-510 [Abstract] [Full Text]  
• Kato, N., Liu, C., Kato, H., Watanabe, K., Nakamura, H., Iwai, N., Ueno, K. (1999). Prevalence of Enterotoxigenic Bacteroides fragilis in Children with Diarrhea in Japan. J. Clin. Microbiol. 37: 801-803 [Abstract] [Full Text]  
• Wu, S., Lim, K.-C., Huang, J., Saidi, R. F., Sears, C. L. (1998). Bacteroides fragilis enterotoxin cleaves the zonula adherens protein, E-cadherin. Proc. Natl. Acad. Sci. USA 95: 14979-14984 [Abstract] [Full Text]  
• Massova, I., Kotra, L. P., Fridman, R., Mobashery, S. (1998). Matrix metalloproteinases: structures, evolution, and diversification. FASEB J. 12: 1075-1095 [Abstract] [Full Text]  
• Moncrief, J. S., Duncan, A. J., Wright, R. L., Barroso, L. A., Wilkins, T. D. (1998). Molecular Characterization of the Fragilysin Pathogenicity Islet of Enterotoxigenic Bacteroides fragilis. Infect. Immun. 66: 1735-1739 [Abstract] [Full Text]