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Thesis
The complex nature of cobalamin biosynthesis in the pathogenic bacterium Vibrio cholerae
Master of Science (M.S.), Drexel University
Jul 2019
DOI:
https://doi.org/10.17918/78k6-7057
Abstract
Corrinoids are a group of compounds that are only synthesized de novo by a select group of bacteria and archaea. Vitamin B12, a necessary supplement for human health, belongs to the most prominent group of corrinoids, the cobalamins. Some prokaryotes contain partial cobalamin biosynthetic pathways, through which they can complete corrinoid intermediates (salvaging) or convert between variants (remodeling). Vibrio cholerae, the etiological agent responsible for the diarrheal disease cholera, lives in two environments with considerable access to variants of vitamin B12. We have previously shown that V. cholerae is capable of salvaging the intermediate cobinamide (Cbi) and selectively remodeling the variant pseudocobalamin (psCbl) without the canonical remodeling protein CbiZ. Cobalamin synthase (CobS) is an integral transmembrane protein responsible for the condensation reaction in cobalamin biosynthesis. We hypothesized that CobS may be recruiting an unknown remodeling protein or acting as a scaffolding protein for a remodeling complex. To further investigate CobS's role in this process, we assayed strains of V. cholerae carrying CobS point mutants or fluorescently tagged Cob proteins. Through corrinoid supplementation assays and liquid chromatography mass spectrometry (LC-MS) analysis, we identified a residue that is required for the remodeling of psCbl but not the salvaging of Cbi. Utilizing fluorescent confocal microscopy, we were able to establish the localization patterns of CobS and three cytosolic Cob proteins in various backgrounds of V. cholerae. Our results suggest that V. cholerae's CobS is not acting as a scaffolding protein but may have an additional role in the remodeling pathway.
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Details
- Title
- The complex nature of cobalamin biosynthesis in the pathogenic bacterium Vibrio cholerae
- Creators
- Breanna Kathryn Tyrell - DU
- Contributors
- Amy T. Ma (Advisor) - Drexel University (1970-)Akhil B. Vaidya (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- ix, 78 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- Microbiology and Immunology; College of Medicine; Drexel University
- Other Identifier
- 9798; 991014632156404721