Role of VimA in Cell Surface Biogenesis in Porphyromonas gingivalis

<p><em>Porphyromonas gingivalis </em>is an important etiological agent of periodontal disease - a disease that affects an estimated 49,000,000 people in the United States of America. Periodontal disease includes gingivitis – inflammation of the gums, and periodontitis – destruction of the teeth and their supporting tissues. <em>Porphyromonas gingivalis </em>is associated with the chronic form of periodontal disease in addition to several systemic diseases.</p> <p>The <em>vimA </em>gene of <em>P. gingivalis </em>has been previously shown to play a significant role in the biogenesis of gingipains (trypsin-like cysteine proteases). The <em>vimA </em>has also been demonstrated to play a role in hemolysis, hemagglutination, autoaggregation, posttranslational protein modification, and LPS biogenesis. Though significant progress has been made in characterizing this gene, much remained unsolved prior to this work, especially as it relates to the molecular mechanisms and interactions of this protein in surface biogenesis, transport and membrane integrity. The focus of our work was to clarify the role of VimA on cell surface biogenesis. We were able to show via TEM and AFM that there were significant differences between the v<em>imA</em>-defective mutant (FLL92) and the wild-type (W83). Particularly, the topography of FLL92 showed numerous fine structures compared with W83, and had an irregular, loosely bound capsule. Fimbrial synthesis was also affected by the VimA mutation. FimA coupled immunogold particles localized with the abundant fimbrial appendages in FLL92, compared with only a few adhering in W83. Lectins were used to clarify the effect of the <em>vimA </em>mutation on the</p> <p>glycosylation of outer-membrane proteins. Outer membrane proteins glycosylated with Galactose (β 1,3) N-Acetylgalactosamine, N-acetyl-α-D-galactosamine, Galactose (β 1,4) N-Acetylglucosamine, N-acetyl-D-galactosamine and Sialic Acid (N-Acetyl neuramic acid) were affected by the <em>vimA </em>mutation. Mass Spectrometric analysis of outermembrane and extracellular proteins identified several proteins in FLL92 that were aberrantly expressed, missing and of varying abundance. In-silico analysis of VimA predicted a likely role as an acyl transferase, with structural similarities to the FemABX family of proteins – these proteins are involved in peptidoglycans synthesis. The expression profile of lipid modified 3H labeled outer membrane proteins from FLL92 when compared with W83 was unchanged; however, a 27 kDa protein was observed in the extracellular fraction of FLL92 that was twice as abundant in FLL92 as in W83. Peptidoglycans isolated from FLL92 were shown to be dissimilar from those isolated from W83 via TEM and AFM, with a slower rate of hydrolysis when exposed to peptidoglycan specific hydrolytic enzymes. Taken together, we provide evidence that the VimA in an important regulator of membrane biogeneis, and is a putative lipid transferase.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Basic Sciences

Year

2011

Author dc:creator

• Osbourne, Devon, Jr.

Contributors dc:contributor

• Fletcher, Hansel M.
• Duerksen-Hughes, Penelope
• Johnson, Mark
• Perry, Christopher
• Soto-Wegner, Ubaldo

• Medical Genetics
• Medical Microbiology
• VimA gene
• Cell Surface Biogenesis
• Membrane biogenesis
• Putative Lipid Transferase
• Gingivitas
• Gingipain

Statement dc:rights

• This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Language dc:language

English

Repository record dc:identifier

https://scholarsrepository.llu.edu/etd/52

OAI identifier oai:identifier

oai:scholarsrepository.llu.edu:etd-1051