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Principal Investigator: Sandipan Chowdhury
Organization: UNIVERSITY OF IOWA
Fiscal Year: 2024
Award: $337,351
Funding agency: National Institute of General Medical Sciences
Mechanisms of voltage regulation of membrane transport
SLC9 family of membrane transporters couple the import of sodium ions to export of protons.
They are vital for regulation of cytoplasmic and endosomal pH, which in turn affect several
physiological processes. Their disfunction has been linked to many diseases such as diabetes,
hypertension, heart failure and cancer. Genetic mutations in specific SLC9 members have also
been associated with Angelman-syndrome like disorders, ADHD, familial autism, epilepsies and
male infertility. The SLC9C1 is a unique member of the SLC9 family. Unlike other SLC9s which
feature a membrane delimited sodium-hydrogen exchange (NHE) domain and a usually short and
relatively unstructured C-terminal soluble domain, SLC9C1 combines an NHE, a voltage-sensing
domain (VSD) and a cyclic nucleotide binding domain (CNBD), interconnected via long, structured
linkers, in a single polypeptide. Recent foundational experiments have revealed that membrane
hyperpolarization and binding of cyclic nucleotides potentiates ion transport via SLC9C1. Its
unique design makes it impossible to predict how voltage and ligand regulation of this protein is
manifested at a structural level. SLC9C1 exhibits sperm-specific expression and has been shown
to be critical for sperm motility in mouse and humans. Sperm motility is robustly modulated by
changes in membrane voltage, intracellular cAMP levels and pH and all these stimuli influence
SLC9C1 mediated ion exchange directly, making it vital to understand the molecular
underpinnings of such diverse regulation. To this end, in this proposal we will integrate single-
particle cryo-electron microscopy and reconstruction techniques with biochemical and
electrophysiological methods to explore key biophysical mechanisms of SLC9C1. In Aim 1, we
will determine the first high-resolution structure of SLC9C1 and identify the key interactions
governing its organization. In Aim 2, we will elucidate the structural rearrangements in SLC9C1
triggered by cyclic nucleotide binding and use electrophysiology to test the role of a key interface
in mediating the regulatory effects of the CNBD. In Aim 3, we will determine how pH and permeant
ions affect the structure and function of SLC9C1. The proposal has a strong scientific foundation
built on our rigorous preliminary studies. It is innovative as it will provide the first snapshots of a
novel membrane protein in different conformations and test provocative hypotheses on the
mechanisms of voltage and cyclic nucleotide regulation of a transporter. The insights obtained
from our studies will aid structure-based drug design for treatment of male infertility. It will also
have broad implications on the structural and functional mechanisms of SLC9 regulation by their
cytoplasmic domains further underscoring its importance for human health.
Terms: <3'5'-cyclic ester of AMP><AD/HD><ADHD><ASD><Action Potentials><Activities of Daily Living><Activities of everyday life><Address><Adenosine Cyclic 3',5'-Monophosphate><Adenosine Cyclic Monophosphate><Adenosine, cyclic 3',5'-(hydrogen phosphate)><Affect><Angelman Syndrome><Architecture><Assay><Attention deficit hyperactivity disorder><Autism><Autistic Disorder><Autoregulation><Binding><Bioassay><Biochemical><Biological Assay><Biophysical Process><C-terminal><CCL21><CCL21 gene><CKb9><Cancers><Capacitation of Spermatozoa><Cardiac><Cations><Cell Body><Cell Growth in Number><Cell Multiplication><Cell Proliferation><Cells><Cellular Proliferation><Charge><Chemicals><Choline><Couples><Cryo-electron Microscopy><Cryoelectron Microscopy><Cues><Cyclic AMP><Cyclic GMP><Cyclic Nucleotides><Cytoplasm><Cytoplasmic Domain><Cytoplasmic Tail><DNA Alteration><DNA Sequence Alteration><DNA mutation><Data><Dependence><Detergents><Development><Diabetes Mellitus><Digestive Diseases><Digestive System Diseases><Digestive System Disorders><Disease><Disorder><Drug Design><Dysfunction><Early Infantile Autism><Echinoidea><Electron Cryomicroscopy><Electrophysiology><Electrophysiology (science)><Endosomes><Engineering / Architecture><Enzyme Gene><Enzymes><Epilepsy><Epileptic Seizures><Epileptics><Esteroproteases><Exhibits><Family><Family member><Fluorescence><Foundations><Functional disorder><GI tract disorder><Genetic mutation><Guanosine Cyclic Monophosphate><H element><H+ element><Happy Puppet Syndrome><Health><Heart failure><Homeostasis><Human><Hydrogen><Hydrogen Ions><Hypertension><Infantile Autism><Intervention><Intervention Strategies><Investigation><Ion Channel Gating><Ion Channel Gatings><Ion Exchange><Ion Transport><Ions><Ischemia-Reperfusion Injury><Kanner's Syndrome><Length><Ligands><Link><Liposomal><Liposomes><MGC34555><Male Infertility><Malignant Neoplasms><Malignant Tumor><Maps><Measures><Mediating><Membrane><Membrane Protein Gene><Membrane Proteins><Membrane Transport><Membrane Transport Proteins><Membrane Transporters><Membrane-Associated Proteins><Methods><Mice><Mice Mammals><Micelles><Modeling><Modern Man><Molecular><Molecular Configuration><Molecular Conformation><Molecular Interaction><Molecular Stereochemistry><Movement><Murine><Mus><Muscular Dystrophies><Myodystrophica><Myodystrophy><Na element><Na+ element><Neurophysiology / Electrophysiology><Organism-Level Process><Organismal Process><Ortholog><Orthologous Gene><Pathologic><Peptidases><Peptide Hydrolases><Phosphatases><Phosphohydrolases><Phosphomonoesterases><Phosphoric Monoester Hydrolases><Photobleaching><Physiologic Processes><Physiological Homeostasis><Physiological Processes><Physiopathology><Play><Point Mutation><Predominantly Hyperactive-Impulsive Type Attention-Deficit Disorder><Predominantly Hyperactive-Impulsive Type Hyperactivity Disorder><Protease Gene><Proteases><Protein Family><Proteinases><Proteins><Proteolytic Enzymes><Protons><Puppet Children><Receptosomes><Regulation><Reperfusion Damage><Reperfusion Injury><Resolution><Role><SCYA21><SLC><Sea Urchins><Seizure Disorder><Sequence Alteration><Sodium><Sodium Chloride><Sperm><Sperm Capacitation><Sperm Motility><Spermatozoa><Stimulus><Structure><Surface Proteins><System><TCA4><Techniques><Testing><Thermodynamic><Thermodynamics><Transmembrane Transport><Variant><Variation><Vascular Hypertensive Disease><Vascular Hypertensive Disorder><adenosine 3'5' monophosphate><autism spectral disorder><autism spectrum disorder><autistic spectrum disorder><biophysical mechanism><body movement><cAMP><cGMP><cardiac failure><conformation><conformational><conformational state><conformationally><conformations><cryo-EM><cryoEM><cryogenic electron microscopy><daily living function><daily living functionality><density><design><designing><developmental><diabetes><digestive disorder><digestive tract disease><dimer><electric field><electrophysiological><epilepsia><epileptogenic><experiment><experimental research><experimental study><experiments><functional ability><functional capacity><gastrointestinal tract disease><gastrointestinal tract disorder><genomic alteration><high blood pressure><hyperpiesia><hyperpiesis><hypertensive disease><hypertensive disorder><innovate><innovation><innovative><insight><interfacial><intervention design><interventional strategy><malignancy><member><membrane structure><muscle dystrophy><mutant><neoplasm/cancer><novel><particle><pathophysiology><pharmacologic><polypeptide><puppetlike syndrome><reconstitute><reconstitution><reconstruction><resolutions><salt><single molecule><social role><sodium ion><sperm cell><sperm mobility><therapy design><treatment design><voltage><zoosperm>