Document Type

Open Access Thesis

Embargo Period

11-28-2016

Degree Program

Microbiology

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2017

Month Degree Awarded

February

Advisor Name

Yasu

Advisor Middle Initial

S

Advisor Last Name

Morita

Abstract

Mycobacteria are atypical bacteria possessing unusual cell envelopes comprised of an outer membrane, covalently linked to an arabinogalacatan-peptidoglycan structure via waxy mycolic acids, in addition to the conventional inner membrane. This thick and highly impermeable cell envelope is a major deterrent to antibiotic treatment of clinically relevant mycobacterial pathogens, including Mycobacterium tuberculosis (Mtb), which infects a third of the world’s population and kills millions each year. Thus, the regulation of mycobacterial cell envelope biosynthesis is of great interest for the development of more effective therapeutics for treating Mtb infections. Using the model organism Mycobacterium smegmatis (M. smegmatis), we identified a novel protein, Spe2, with an unknown role in the biosynthesis of the cell envelope glycolipids lipomannan (LM) and lipoarabinomannan (LAM). Based on the observation that Δspe2 mutants produce truncated LM/LAM, I speculated Spe2 might enhance the elongation of these products. Here, I use biochemical assays to show Spe2 is localized to the periplasm where it can directly interact with the LM/LAM biosynthetic pathway. I further utilize a genetic approach to demonstrate that Spe2 acts at the stage in which the mannosyltransferase MptA mediates periplasmic LM elongation. Moreover, native polyacrylamide gel electrophoresis (PAGE) and co-immunoprecipitation techniques failed to reveal Spe2 protein binding partners. Together, these data suggest Spe2 is a periplasmic protein involved in regulating LM/LAM biosynthesis, perhaps through direct interactions with LM intermediates.

Included in

Bacteriology Commons

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