A phage protein that inhibits the bacterial ATPase required for type IV pilus assembly

In-Young Chung, Hye-Jeong, Hee-Won Bae, and You-Hee Cho

PNAS 2014 111:31

Speaker: Beatrice Lin (林怡慈)                        Time: 14:00~15:00, Sep.24, 2014

Commentator: Dr. Lien-I Hor (何漣漪老師)       Place: Room 601

Abstract:

Type IV pili (TFPs) are required for bacterial twitching motility, which is critical for biofilm formation and pathogenicity of Pseudomonas aeruginosa. Temperate phages, which are viruses that invade only bacteria, have the tendency to lysogenize rather than killing the host (1). Many P. aeruginosa phages, such as D3112 and MP22, require TFP-mediated twitching motility for infection. The authors previously reported that after infection, D3112 could block infection by a second phage MP22, but not vice versa (2). In this study, the authors identified a D3112 encoded protein gp05 (Tip) based on a comparison of whole genome sequences of D3112 and MP22, which is necessary and sufficient for twitching inhibition and subsequent superinfection exclusion. By using pull-down assay and MALDI-TOF MS analysis, it was identified that Tip interacts specifically with PilB, an ATPase protein required for TFP assembly and extension. Furthermore, using truncation analysis and bacterial two-hybrid assay, an internal 40-aa region of PilB is identified to be critical for interaction with Tip. Finally, the authors found that inhibition of PilB activity by Tip resulted in no TFP formation on the bacterial surface and this is due to the delocalization of PilB from the poles. In conclusion, the authors identified a novel method for superinfection exclusion based on inhibition of twitching motility, which could lead to the development of novel antibacterial strategy.

References:

1.     Brüssow H, Canchaya C, Hardt WD. (2004) Phages and the evolution of bacterial pathogens: From genomic rearrangements to lysogenic conversion. Microbiol Mol Biol Rev. 68(3):560–602.

2.     Heo Y-J, Chung I-Y, Choi KB, Lau GW, Cho Y-H (2007) Genome sequence comparison and superinfection between two related Pseudomonas aeruginosa phages, D3112and MP22. Microbiology 153(Pt 9): 2885–2895.