Glucose is a ubiquitous cellular fuel source in virtually all organisms. In addition to its energetic role in the human body, glucose also serves as a critical metabolic intermediate in which activated glucose molecules are transported to the ER and Golgi and used for glycosylating proteins, lipids and polysaccharides as part of the biosynthetic-secretory pathway. The path of entry to the body is common for glucose and the other dietary monosaccharides, which are absorbed by enterocytes of the small intestine and distributed throughout the body in the bloodstream. The plasma glucose concentration is tightly maintained by hormonal control and conserved reabsorption mechanisms in the kidneys. Secondary active transporters facilitate these absorption/reabsorption processes as well as the exclusive delivery of activated glucose molecules to the ER and Golgi. Alterations in their inherent functions result in numerous human diseases and disorders, such as type II diabetes; thus, an intricate understanding of their structure and dynamics is a critical objective for biomedical research. During the original grant cycle, we solved the first crystal structure for an member of the sodium glucose transporter family, the Vibrio parahaemolyticus sodium/galactose symporter (vSGLT). On the subsequent renewal, we solved additional structures of the inward-open conformation of vSGLT, which in conjunction with biochemical and molecular dynamics simulations reveals the mechanism allowing substrate release. These two distinct conformations obtained during the course of this grant have fundamentally advanced our understanding of membrane transport to an atomic level and are the foundation for this competitive renewal. In addition, we aim to resolve mammalian transporters (in particular Homo sapiens) of SGLT (SLC5 family) as well as a distinct, and as of yet structurally unresolved class of nucleotide sugar transporters, the SLC35 family.
The aims of this renewal are:
Aim 1 captures a complete transport cycle for vSGLT using double electron-electron resonance and wide-angle x-ray scattering.
Aims 2 and 3 structurally resolve two classes of human transporters with pharmaceutical relevance, the Solute Sodium Symporter family (SLC5) and the Nucleotide Sugar Transporters family (SLC35). Elucidating the structural basis for these transport families will increase our understanding of the related diseases and aid in drug development.

Public Health Relevance

Secondary active transporters are essential components of physiology in all organisms. As such, they are implicated in numerous diseases and are designated targets for pharmaceutical compounds. These studies will capture the mechanism of the sodium galactose transporter at an atomic resolution as it proceeds through its reaction cycle by harnessing crystallography, spectroscopy, advanced x-ray scattering and Molecular Dynamics simulations, using a bacterial transporter as a model system. In addition we will structurally resolve human sugar transporters from two different and essential classes that bear a tremendous pharmaceutical relevance in type II diabetes and other conditions related to sugar transport and metabolism.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM078844-10
Application #
8889023
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Chin, Jean
Project Start
2006-07-01
Project End
2019-06-30
Budget Start
2015-07-01
Budget End
2016-06-30
Support Year
10
Fiscal Year
2015
Total Cost
Indirect Cost
Name
University of California Los Angeles
Department
Physiology
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Bergdoll, Lucie A; Lerch, Michael T; Patrick, John W et al. (2018) Protonation state of glutamate 73 regulates the formation of a specific dimeric association of mVDAC1. Proc Natl Acad Sci U S A 115:E172-E179
Pantazis, Antonios; Westerberg, Karin; Althoff, Thorsten et al. (2018) Harnessing photoinduced electron transfer to optically determine protein sub-nanoscale atomic distances. Nat Commun 9:4738
Wahlgren, Weixiao Y; Dunevall, Elin; North, Rachel A et al. (2018) Substrate-bound outward-open structure of a Na+-coupled sialic acid symporter reveals a new Na+ site. Nat Commun 9:1753
Paz, Aviv; Claxton, Derek P; Kumar, Jay Prakash et al. (2018) Conformational transitions of the sodium-dependent sugar transporter, vSGLT. Proc Natl Acad Sci U S A 115:E2742-E2751
Gorraitz, Edurne; Hirayama, Bruce A; Paz, Aviv et al. (2017) Active site voltage clamp fluorometry of the sodium glucose cotransporter hSGLT1. Proc Natl Acad Sci U S A 114:E9980-E9988
Budelier, Melissa M; Cheng, Wayland W L; Bergdoll, Lucie et al. (2017) Photoaffinity labeling with cholesterol analogues precisely maps a cholesterol-binding site in voltage-dependent anion channel-1. J Biol Chem 292:9294-9304
Adelman, Joshua L; Ghezzi, Chiara; Bisignano, Paola et al. (2016) Stochastic steps in secondary active sugar transport. Proc Natl Acad Sci U S A 113:E3960-6
Li, Zheng; Lee, Ashely S E; Bracher, Susanne et al. (2015) Identification of a second substrate-binding site in solute-sodium symporters. J Biol Chem 290:7361
Ji, Jianling; Lee, Hane; Argiropoulos, Bob et al. (2015) DYRK1A haploinsufficiency causes a new recognizable syndrome with microcephaly, intellectual disability, speech impairment, and distinct facies. Eur J Hum Genet 23:1473-81
Choudhary, Om P; Paz, Aviv; Adelman, Joshua L et al. (2014) Structure-guided simulations illuminate the mechanism of ATP transport through VDAC1. Nat Struct Mol Biol 21:626-32

Showing the most recent 10 out of 33 publications