Structural and Mechanistic Interrogation of Fatty Acid Biosynthesis Machinery

by Aybeg Nafiz Günenç
Doctoral thesis
Date of Examination:2024-05-27
Date of issue:2025-05-22
Advisor:Prof. Dr. Holger Stark
Referee:Prof. Dr. Jörg Stülke
Referee:Prof. Dr. Henning Urlaub
Referee:Dr. Ashwin Chari
Persistent Address: http://dx.doi.org/10.53846/goediss-11289

 

 

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Abstract

English

Lipids are important molecules for vital functions in the cell, such as energy storage, membrane structure, cellular signaling, and metabolic control. Lipid metabolism is thus one of the central pathways of all living beings. Fatty acids are important building blocks of lipids such as triglycerides and phospholipids. Their synthesis and degradation are quite labor-intensive, complex mechanisms that need in-depth research. Because energetically unfavorable processes revolve around fatty acid synthesis, their utilization from external sources remains an important means of survival. One of these utilization pathways is facilitated through enzymes that are called as acyl-acyl carrier protein synthetases (AAS), which are a central factor for bacterial lipid metabolism. AAS enzymes are found to be quite important for the survival of bacteria, especially in the context of bacterial infection, making them a potential target for antimicrobial development. In this thesis, an AAS enzyme found in the marine bacterium Vibrio harveyi, here abbreviated as VhAAS, has been subjected to structure-function studies. For this purpose, VhAAS has been purified, alongside with its peptide substrate, the acyl carrier protein (ACP). The enzyme has then been crystallized to determine its structure, and structurally characterize its functional states. The enzyme has also been biochemically characterized via enzymatic assays. Here we report the first structural model of VhAAS, where it is observed as a hexamer, together with 4 different functional states. The states were characterized using sucrose gradients, chromatographic procedures and enzymatic assays. This study is the first structural characterization of this enzyme and is important to understand related AAS enzymes, which are biomedically relevant as a drug target.
Keywords: Acyl Carrier Protein; Fatty Acid Synthesis; X-ray Crystallography; Acyl-ACP Synthetase
 
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