Project

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Multienzymes and the Regulation of Eukaryotic Lipid Metabolism

Applicant Maier Timm
Number 138262
Funding scheme Project funding
Research institution Biozentrum der Universität Basel Systembiologie
Institution of higher education University of Basel - BS
Main discipline Molecular Biology
Start/End 01.01.2012 - 31.12.2014
Approved amount 623'000.00
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All Disciplines (2)

Discipline
Molecular Biology
Biophysics

Keywords (6)

Multienzymes; Structural Biology; Metabolism; X-ray Crystallography; Lipid Metabolism; Fatty Acid Metabolism

Lay Summary (English)

Lead
Lay summary

As the universal main component of cell membranes, lipids form the barrier between the inside of a cell and its surroundings. They are the most important energy storage compounds in our body and act as messengers and transmitters. The abnormal regulation of lipid metabolism plays an important role in the development if cancer and is a very common risk factor for cardiovascular disease and type 2 diabetes.

This project focuses on multifunctional protein complexes as key players in the biosynthesis of lipids and their constituent fatty acids and in metabolic regulation. The goal is to determine the complex structures of enzymes involved in lipid and fatty acid metabolism down to the atomic level. From these structures and further experiments we deduce the mechanism of action of multifunctional proteins and establish opportunities for manipulating them. An example of such proteins is fatty acid synthase, a complex multienzyme in fatty acid biosynthesis and a metabolic oncogene and prognostic maker for tumor malignancy. As a key method for structure determination of large biomacromolecular complexes we employ X-ray crystallography. Our structural and functional data help to gain an understanding of the complex multifunctional proteins typical for human metabolism and deliver starting points for the design or optimization of metabolism-based drugs.

Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Evolutionary Origins of the Multienzyme Architecture of Giant Fungal Fatty Acid Synthase
Bukhari Habib S. T., Jakob Roman P., Maier Timm (2014), Evolutionary Origins of the Multienzyme Architecture of Giant Fungal Fatty Acid Synthase, in STRUCTURE, 22(12), 1775-1785.
Conserved sequence motifs and the structure of the mTOR kinase domain
Sauer Evelyn, Imseng Stefan, Maier Timm, Hall Michael N. (2013), Conserved sequence motifs and the structure of the mTOR kinase domain, in BIOCHEMICAL SOCIETY TRANSACTIONS, 41, 889-895.

Collaboration

Group / person Country
Types of collaboration
Peter Leadlay, University of Cambridge Great Britain and Northern Ireland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Exchange of personnel
François Diederich, ETH Zürich Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Michael N. Hall, Biozentrum, Uni Basel Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Michael D Burkart, UCSD, LaJolla United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results

Associated projects

Number Title Start Funding scheme
145023 Advanced Imaging System for Biomolecular Crystallization Screening 01.12.2012 R'EQUIP
179323 Macromolecular Assemblies in Metabolic Regulation and Polyketide Biosynthesis 01.04.2018 Project funding
159696 Multienzymes in Lipid and Polyketide Biosynthesis 01.04.2015 Project funding
144183 The Bacterial Lectin FimH - High and Low Affinity States 01.10.2012 Project funding
150814 Purchase of a 900 MHz high-resolution NMR instrument 01.12.2013 R'EQUIP
125357 Structure and substrate-transfer mechanism of bimodular polyketide megasynthases 01.09.2009 Project funding

Abstract

Lipid biosynthesis and degradation are essential and tightly regulated cellular processes in all organisms and they are closely linked to human health with implications for diabetes, atherosclerosis and cancer. Compared to other metabolic processes, our structural and mechanistic insights into lipid metabolism are still limited. The key reason for difficulties in studying eukaryotic lipid metabolism at the molecular level is the complicated nature of central players: Early steps of lipid biosynthesis are catalyzed by highly complex multienzymes, pyruvate dehydrogenase complex (PDC), acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), and multifunctional enzymes are involved in fatty acid degradation. Later steps of lipids biosynthesis are catalyzed by membrane bound enzymes. Also the regulation of lipid homeostasis involves dynamic multi-subunit assemblies, such as mammalian target of rapamycin (mTOR) complexes, or membrane bound sensor systems for lipid or sterol composition. The aim of the current project is to provide structural insights into the regulation and functioning of key steps of eukaryotic lipid metabolism. The project is divided into three subprojects focusing on ACC, FAS and mTOR. ACC catalyzes the committed step in fatty acid biosynthesis, and mediates short-term regulation by allosteric modulation and phosphorylation. While structures of isolated ACC domains have provided insights into the catalytic mechanism of individual active sites, we are aiming to determining the structure of intact ACC, which is required to understand its regulatory properties. With the structure of metazoan FAS we already revealed the architecture of this highly complex multienzyme. However, we are still lacking information on the critical aspect of substrate transfer in FAS and related megasynthases because the intrinsically mobile substrate carrier domain (ACP) was not resolved in our analysis. We are thus now employing mechanism-based trapping of the ACP domain to allow its visualization in a functional complex with enzymatic domains in the FAS multienzyme. mTOR is a large multidomain protein with kinase activity, which serves as a nucleus for two functionally distinct multiprotein assemblies, complex 1 and 2. These complexes play a key role in integrating metabolic and hormonal signaling for regulating the balance between anabolism and catabolism, particularly in lipid metabolism. The current models of mTOR complexes are obtained by electron microscopy at low resolution and provide only limited functional insights. High resolution structural studies have so far been carried out only on very small isolated domains, excluding the most relevant kinase part of mTOR. In collaboration with M. Hall we are now tackling structural determination of mTOR starting with multidomain TOR fragments, but with the intent to further study intact TOR and even multi-subunit assemblies. Together, these studies will help to advance our understanding of key regulatory and mechanistic aspects in eukaryotic lipid metabolism and are well supported by outside collaborations and synergies within our team.
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