Document text
Principal Investigator: Merritt C Maduke
Organization: STANFORD UNIVERSITY
Fiscal Year: 2024
Award: $473,494
Funding agency: National Institute of General Medical Sciences
The CLC (“Chloride Channel”) family encompasses two major ion-transport mechanisms: half
of CLC homologs are electrodiffusive ion channels, and half are secondary active transporters
that stoichiometrically exchange Cl– for H+. The occurrence of two mechanisms in one family
suggests they operate by variations on a common theme. Indeed, experimental results support
the hypothesis that CLC channels are “broken” transporters, in which tight coordination between
inner and outer gates is lost. Thus, subtle differences in protein conformational dynamics and ion
binding—and the interactions between them—can produce two different types of ion transport
behavior in proteins with the same secondary structure. Understanding the molecular basis of
these differences will inform our understanding of both CLC channels and transporters.
As secondary active transporters, CLC transporters harness energy stored in one ion's
electrochemical gradient (Cl– or H+) to pump the other ion against its gradient. This occurs through
tight coupling of protein conformational changes to ion binding and transport events. To develop
a fully integrated structural description of ion coupling in the CLC transport mechanism, this
project will combine complementary cutting-edge approaches, including cryo-electron microscopy
to determine high-resolution structures, double electron-electron resonance spectroscopy to
monitor the conformational state of the transporter under different conditions and with different
mutations, MD simulations to determine hydration pathways under various conditions, and
quantitative functional assays to connect structural dynamics to function.
Terms: <Active Biologic Transport><Active Biological Transport><Active Transport><Affect><Anions><Aquaporins><Assay><Behavior><Binding><Bioassay><Biological Assay><Body Tissues><Carrier Proteins><Cations><Chloride Channels><Chloride Ion Channels><Coupled><Coupling><Cryo-electron Microscopy><Cryoelectron Microscopy><Crystallographies><Crystallography><Data><Electron Cryomicroscopy><Electrons><Event><Family><GeneHomolog><Genetic Alteration><Genetic Change><Genetic defect><H+ element><Homolog><Homologous Gene><Homologue><Human><Hydration><Hydration status><Hydrogen Ions><Hydrogen Oxide><Hypertension><Ion Channel><Ion Transport><Ionic Channels><Ions><Kidney Diseases><Kinetics><Knowledge><Measurement><Membrane Channels><Methodology><Modeling><Modern Man><Molecular><Molecular Configuration><Molecular Conformation><Molecular Interaction><Molecular Stereochemistry><Monitor><Movement><Muscle><Muscle Tissue><Mutation><Negative Beta Particle><Negatrons><Nephropathy><Nervous System Diseases><Nervous System Disorder><Neurologic Disorders><Neurological Disorders><Organism><Pathway interactions><Play><Process><Protein Conformation><Protein Region><Proteins><Protons><Pump><Renal Disease><Resolution><Role><Secondary to><Side><Spectroscopy><Spectrum Analyses><Spectrum Analysis><Structure><Testing><Tissues><Transport Protein Gene><Transport Proteins><Transporter Protein><Uphill Transport><Variant><Variation><Vascular Hypertensive Disease><Vascular Hypertensive Disorder><Water><Water Channel Proteins><antiporter><biophysical approaches><biophysical methodology><biophysical methods><biophysical techniques><body movement><bone><conformation><conformational><conformational state><conformationally><conformations><crosslink><cryo-EM><cryoEM><cryogenic electron microscopy><design><designing><extracellular><genome mutation><high blood pressure><hyperpiesia><hyperpiesis><hypertensive disease><hypertensive disorder><kidney disorder><living system><muscular><mutant><neurological disease><pathway><public health relevance><renal disorder><resolutions><simulation><social role><water channel><water transporter>