Structural and functional insights into membrane transport mechanisms
Abstract/Contents
- Abstract
- All cells are surrounded by a lipid bilayer that prevents many chemical species from crossing including key biomolecules. Transport proteins facilitate the passage of a wide range of molecules across the cell membrane. Molecular details of transport protein function, such as mechanisms of substrate specificity, gating, and conformational change can be gleaned from high-resolution structures. To this end, I utilized structural approaches to develop models for different transport mechanisms. In the first section, I focus on a family of sugar transporters called SWEETs. SWEETs play central roles in plant biology and are found across all lifeforms including humans. Their prokaryotic homologs, SemiSWEETs, are amongst the smallest natural transporters. I focused on SemiSWEET as a representative system for SWEET function and as a model for other more complex transporters. High resolution structures of SemiSWEET in all major conformational states revealed the movement of hydrophobic gate residues controls the accessibility of the substrate-binding binding pocket. A glucose-bound structure revealed the substrate recognition residues. Structural observations were corroborated by mutagenesis, sugar uptake experiments, and unguided molecular dynamic simulations. The simulations faithfully recapitulate the experimental structures while demonstrating that the substrate doesn't induce conformational changes, but instead takes a "free ride" through a stochastically fluctuating transporter. In addition to the characterization of SemiSWEET, I developed more general protein engineering strategies to facilitate structural studies. The final section details the molecular structure of the mitochondrial calcium uniporter, which required a transmembrane-targeting nanobody in order to achieve the highest resolution crystal structure.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Fastman, Nathan Marc |
|---|---|
| Degree supervisor | Feng, Liang, 1976- |
| Thesis advisor | Feng, Liang, 1976- |
| Thesis advisor | Kobilka, Brian K |
| Thesis advisor | Maduke, Merritt C, 1966- |
| Degree committee member | Kobilka, Brian K |
| Degree committee member | Maduke, Merritt C, 1966- |
| Associated with | Stanford University, Biophysics Program. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Nathan Fastman. |
|---|---|
| Note | Submitted to the Biophysics Program. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Nathan Marc Fastman
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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