This Article Full Text Full Text (PDF) Other Versions of this Article: JB.00138-07v1 189/14/5022    most recent 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 Han, X. Articles by Rood, J. I. Search for Related Content PubMed PubMed Citation Articles by Han, X. Articles by Rood, J. I.

Type IV Fimbrial Biogenesis Is Required for Protease Secretion and Natural Transformation in Dichelobacter nodosus

Australian Research Council Centre of Excellence in Structural and Functional Microbial Genomics, Department of Microbiology, Monash University, Victoria 3800, Australia

Received 28 January 2007/ Accepted 9 May 2007

The objective of this study was to develop an understanding of the molecular mechanisms by which type IV fimbrial biogenesis, natural transformation, and protease secretion are linked in the ovine foot rot pathogen, Dichelobacter nodosus. We have shown that like the D. nodosus fimbrial subunit FimA, the pilin-like protein PilE and the FimN, FimO, and FimP proteins, which are homologs of PilB, PilC, and PilD from Pseudomonas aeruginosa, are essential for fimbrial biogenesis and natural transformation, indicating that transformation requires an intact type IV fimbrial apparatus. The results also showed that extracellular protease secretion in the fimN, fimO, fimP, and pilE mutants was significantly reduced, which represents the first time that PilB, PilC, and PilE homologs have been shown to be required for the secretion of unrelated extracellular proteins in a type IV fimbriate bacterium. Quantitative real-time PCR analysis of the three extracellular protease genes aprV2, aprV5, and bprV showed that the effects on protease secretion were not mediated at the transcriptional level. Bioinformatic analysis did not identify a classical type II secretion system, and the putative fimbrial biogenesis gene pilQ was the only outer membrane secretin gene identified. Based on these results, it is postulated that in D. nodosus, protease secretion occurs by a type II secretion-related process that directly involves components of the type IV fimbrial biogenesis machinery, which represents the only type II secretion system encoded by the small genome of this highly evolved pathogen.

Published ahead of print on 18 May 2007.

This article has been cited by other articles:

• Chakraborty, S., Monfett, M., Maier, T. M., Benach, J. L., Frank, D. W., Thanassi, D. G. (2008). Type IV Pili in Francisella tularensis: Roles of pilF and pilT in Fiber Assembly, Host Cell Adherence, and Virulence. Infect. Immun. 76: 2852-2861 [Abstract] [Full Text]  
• Han, X., Kennan, R. M., Davies, J. K., Reddacliff, L. A., Dhungyel, O. P., Whittington, R. J., Turnbull, L., Whitchurch, C. B., Rood, J. I. (2008). Twitching Motility Is Essential for Virulence in Dichelobacter nodosus. J. Bacteriol. 190: 3323-3335 [Abstract] [Full Text]  
• Chiang, P., Sampaleanu, L. M., Ayers, M., Pahuta, M., Howell, P. L., Burrows, L. L. (2008). Functional role of conserved residues in the characteristic secretion NTPase motifs of the Pseudomonas aeruginosa type IV pilus motor proteins PilB, PilT and PilU. Microbiology 154: 114-126 [Abstract] [Full Text]