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Journal of Bacteriology, November 2008, p. 7022-7034, Vol. 190, No. 21
0021-9193/08/$08.00+0     doi:10.1128/JB.00938-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Novel Proteins That Modulate Type IV Pilus Retraction Dynamics in Pseudomonas aeruginosa{triangledown}

Miranda L. Asikyan,1,2,{dagger} Julianne V. Kus,3,{dagger} and Lori L. Burrows1,2,3*

Department of Biochemistry and Biomedical Sciences,1 The Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario L8N 3Z5,2 The Faculty of Dentistry, University of Toronto, Toronto, Ontario M5G 1G6, Canada3

Received 9 July 2008/ Accepted 25 August 2008

Pseudomonas aeruginosa uses type IV pili to colonize various materials and for surface-associated twitching motility. We previously identified five phylogenetically distinct alleles of pilA in P. aeruginosa, four of which occur in genetic cassettes with specific accessory genes (J. V. Kus, E. Tullis, D. G. Cvitkovitch, and L. L. Burrows, Microbiology 150:1315-1326, 2004). Each of the five pilin alleles, with and without its associated pilin accessory gene, was used to complement a group II PAO1 pilA mutant. Expression of group I or IV pilA genes restored twitching motility to the same extent as the PAO1 group II pilin. In contrast, poor twitching resulted from complementation with group III or group V pilA genes but increased significantly when the cognate tfpY or tfpZ accessory genes were cointroduced. The enhanced motility was linked to an increase in recoverable surface pili and not to alterations in total pilin pools. Expression of the group III or V pilins in a PAO1 pilA-pilT double mutant yielded large amounts of surface pili, regardless of the presence of the accessory genes. Therefore, poor piliation in the absence of the TfpY and TfpZ accessory proteins results from a net increase in PilT-mediated retraction. Similar phenotypes were observed for tfpY single and tfpY-pilT double knockout mutants of group III strain PA14. A PilAV-TfpY chimera produced few surface pili, showing that the accessory proteins are specific for their cognate pilin. The genetic linkage between specific pilin and accessory genes may be evolutionarily conserved because the accessory proteins increase pilus expression on the cell surface, thereby enhancing function.

* Corresponding author. Mailing address: Department of Biochemistry and Biomedical Sciences, Rm. 4H18, Health Sciences Centre, McMaster University, 1200 Main St. W., Hamilton, ON, Canada L8N 3Z5. Phone: (905) 525-9140, ext. 22029. Fax: (905) 522-9033. E-mail: burrowl{at}mcmaster.ca

{triangledown} Published ahead of print on 5 September 2008.

{dagger} These authors contributed equally.

Journal of Bacteriology, November 2008, p. 7022-7034, Vol. 190, No. 21
0021-9193/08/$08.00+0     doi:10.1128/JB.00938-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Harvey, H., Habash, M., Aidoo, F., Burrows, L. L. (2009). Single-Residue Changes in the C-Terminal Disulfide-Bonded Loop of the Pseudomonas aeruginosa Type IV Pilin Influence Pilus Assembly and Twitching Motility. J. Bacteriol. 191: 6513-6524 [Abstract] [Full Text]  
  • Kus, J. V., Kelly, J., Tessier, L., Harvey, H., Cvitkovitch, D. G., Burrows, L. L. (2008). Modification of Pseudomonas aeruginosa Pa5196 Type IV Pilins at Multiple Sites with D-Araf by a Novel GT-C Family Arabinosyltransferase, TfpW. J. Bacteriol. 190: 7464-7478 [Abstract] [Full Text]  


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