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Biophysical and biochemical characterization of proteins involved in a-glucan biosynthesis in mycobacteria

Kermani, Ali Asghar (2016)
Ph.D. thesis, University of Birmingham.

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A capsule composed of mainly α-glucan forms the most outermost layer of cell envelope of Mycobacterium tuberculosis, the causing agent of tuberculosis. Capsule participates in modulating the immune system responses. In GlgE pathway, one of the three pathways involved in α-glucan synthesis, trehalose in converted to glucan through the activity of four enzymes, trehalose synthase, maltokinase Pep2, maltosyltransferase GlgE and branching enzyme GlgB. It has shown that M. tuberculosis TreS and Pep2 form an octameric complex together. During this study we solved the structure of the complex at 3.6 Å in M. smegmatis. The structure reveals two pairs of Pep2 monomers bind to the opposite sides of the diamond shaped TreS tetramer in a 4 + 4 complex. However, studying the stoichiometry of the complex using other techniques such as: ITC, AUC and SAXS indicates a 4 + 2 complex formation in the solution. Moreover, our data using size exclusion chromatography would suggest that this complex formation is pH dependent and favors complex formation at more acidic pHs. This study is a step forward towards better understanding of the capsule synthesis in M. tuberculosis and highlights the role of complex formation between enzymes as an effective strategy to control the metabolic pathways in mycobacteria.

Type of Work:Ph.D. thesis.
Supervisor(s):Futterer, Klaus and Besra, Gurdyal S.
School/Faculty:Colleges (2008 onwards) > College of Life & Environmental Sciences
Department:School of Biosciences
Subjects:QR Microbiology
QR355 Virology
Institution:University of Birmingham
ID Code:6516
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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