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Structure and function of Haloferax volcanii flagella.
- Format:
- Book
- Thesis/Dissertation
- Author/Creator:
- Tripepi, Manuela.
- Language:
- English
- Subjects (All):
- Microbiology.
- 0410.
- Penn dissertations--Biology.
- Biology--Penn dissertations.
- Local Subjects:
- Penn dissertations--Biology.
- Biology--Penn dissertations.
- 0410.
- Physical Description:
- 191 pages
- Contained In:
- Dissertation Abstracts International 74-10B(E).
- System Details:
- Mode of access: World Wide Web.
- text file
- Summary:
- Swimming motility is a process that allows microorganisms to seek favorable conditions and escape toxic ones. In both bacteria and archaea, the rotational movement of flagella confers the ability to swim to these organisms. Interestingly, although the mechanism of action that propels swimming motility is very similar for both bacteria and archaea, archaeal flagella share structural similarities with bacterial type IV pili rather than bacterial flagella. In this study, we characterized the flagella of the haloarchaeon Haloferax volcanii. We defined conditions under which this organism, which was previously reported to be non-motile, exhibits surface motility, and we also confirmed that this motility is flagella-dependent. Furthermore, we developed an adhesion assay to show that surface adhesion of Hfx. volcanii, unlike bacteria and other archaea, does not require flagella. The flagella operon in Hfx. volcanii contains two genes that encode flagellins, flgA1 and flgA2. Using purified flagella, we performed mass spectrometry analysis on the flagellar subunits encoded by these genes and showed that FlgA1 and FlgA2 are the major and minor subunits of the Hfx. volcanii flagellum, respectively. Consistent with FlgA1 being the major subunit, flgA1 deletion strain is non-motile. Surprisingly, a deletion mutant lacking flgA2 displayed a hypermotile phenotype, which has not been reported previously for any flagellin gene deletion mutants. A significantly larger percentage of cells from DeltaflgA2 cultures moved compared to the percentage of cells from wild type cultures, which exhibited slower motility than the cells lacking FlgA2. Finally, both flagellins were predicted to be N-glycosylated. Our in vivo studies confirmed that the three predicted N-glycosylation sites of FlgA1 are N-glycosylated and also showed that the N-glycosylation of FlgA1 involves a process that is similar to that of the S-layer glycoprotein. These analyses also revealed that these modifications are essential for motility. This was the first study demonstrating that glycosylation of the flagella directly affects motility. It also underscores the usefulness of flagellins as reporter genes for glycosylation studies. In summary, this study revealed important details of haloarchaeal flagella structure and function relationship, including the crucial role that glycosylation plays in the motility of Hfx. volcanii.
- Notes:
- Thesis (Ph.D. in Biology) -- University of Pennsylvania, 2013.
- Source: Dissertation Abstracts International, Volume: 74-10(E), Section: B.
- Adviser: Mecky Pohlschrder.
- Local Notes:
- School code: 0175.
- ISBN:
- 9781303175824
- Access Restriction:
- Restricted for use by site license.
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