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Biochemistry, Biophysics, and Structural Biology Commons

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Articles 1 - 5 of 5

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Structures Of Channelrhodopsin Paralogs In Peptidiscs Explain Their Contrasting K+ And Na+ Selectivities, Takefumi Morizumi, Kyumhyuk Kim, Hai Li, Elena G Govorunova, Oleg A Sineshchekov, Yumei Wang, Lei Zheng, Éva Bertalan, Ana-Nicoleta Bondar, Azam Askari, Leonid S Brown, John L Spudich, Oliver P Ernst Jul 2023

Structures Of Channelrhodopsin Paralogs In Peptidiscs Explain Their Contrasting K+ And Na+ Selectivities, Takefumi Morizumi, Kyumhyuk Kim, Hai Li, Elena G Govorunova, Oleg A Sineshchekov, Yumei Wang, Lei Zheng, Éva Bertalan, Ana-Nicoleta Bondar, Azam Askari, Leonid S Brown, John L Spudich, Oliver P Ernst

Journal Articles

Kalium channelrhodopsin 1 from Hyphochytrium catenoides (HcKCR1) is a light-gated channel used for optogenetic silencing of mammalian neurons. It selects K+ over Na+ in the absence of the canonical tetrameric K+ selectivity filter found universally in voltage- and ligand-gated channels. The genome of H. catenoides also encodes a highly homologous cation channelrhodopsin (HcCCR), a Na+ channel with >100-fold larger Na+ to K+ permeability ratio. Here, we use cryo-electron microscopy to determine atomic structures of these two channels embedded in peptidiscs to elucidate structural foundations of their dramatically different cation selectivity. Together with structure-guided mutagenesis, we show that K+ versus Na+ …


Sequential Absorption Of Two Photons Creates A Bistable Form Of Rubyacr Responsible For Its Strong Desensitization, Oleg A Sineshchekov, Elena G Govorunova, Hai Li, Yumei Wang, John L Spudich May 2023

Sequential Absorption Of Two Photons Creates A Bistable Form Of Rubyacr Responsible For Its Strong Desensitization, Oleg A Sineshchekov, Elena G Govorunova, Hai Li, Yumei Wang, John L Spudich

Journal Articles

Channelrhodopsins with red-shifted absorption, rare in nature, are highly desired for optogenetics because light of longer wavelengths more deeply penetrates biological tissue. RubyACRs (Anion ChannelRhodopsins), a group of four closely related anion-conducting channelrhodopsins from thraustochytrid protists, are the most red-shifted channelrhodopsins known with absorption maxima up to 610 nm. Their photocurrents are large, as is typical of blue- and green-absorbing ACRs, but they rapidly decrease during continuous illumination (desensitization) and extremely slowly recover in the dark. Here, we show that long-lasting desensitization of RubyACRs results from photochemistry not observed in any previously studied channelrhodopsins. Absorption of a second photon by …


Targeting Metabolic Alterations Associated With Smooth Muscle Α-Actin Pathogenic Variant Attenuates Moyamoya-Like Cerebrovascular Disease, Anita Kaw May 2023

Targeting Metabolic Alterations Associated With Smooth Muscle Α-Actin Pathogenic Variant Attenuates Moyamoya-Like Cerebrovascular Disease, Anita Kaw

Dissertations & Theses (Open Access)

Heterozygous pathogenic variants in ACTA2, encoding smooth muscle α-actin (α-SMA), predispose to thoracic aortic aneurysms and dissections. De novo missense variants disrupting ACTA2 arginine 179 (p.Arg179) cause a multisystemic disease termed smooth muscle dysfunction syndrome (SMDS), which is characterized by early onset thoracic aortic disease and moyamoya disease-like (MMD) cerebrovascular disease. The MMD-like cerebrovascular disease in SMDS patients is marked by bilateral steno-occlusive lesions in the distal internal carotid arteries (ICAs) and their branches. To study the molecular mechanisms that underlie the ACTA2 p.Arg179 variants, a smooth muscle-specific Cre-lox knock-in mouse model of the heterozygous Acta2 R179C variant, termed …


Lipid Nanoparticle-Mediated Mrna Delivery In Lung Fibrosis, Matteo Massaro, Suhong Wu, Gherardo Baudo, Haoran Liu, Scott Collum, Hyunho Lee, Cinzia Stigliano, Victor Segura-Ibarra, Harry Karmouty-Quintana, Elvin Blanco Apr 2023

Lipid Nanoparticle-Mediated Mrna Delivery In Lung Fibrosis, Matteo Massaro, Suhong Wu, Gherardo Baudo, Haoran Liu, Scott Collum, Hyunho Lee, Cinzia Stigliano, Victor Segura-Ibarra, Harry Karmouty-Quintana, Elvin Blanco

Journal Articles

mRNA delivery enables the specific synthesis of proteins with therapeutic potential, representing a powerful strategy in diseases lacking efficacious pharmacotherapies. Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by excessive extracellular matrix (ECM) deposition and subsequent alveolar remodeling. Alveolar epithelial type 2 cells (AEC2) and fibroblasts represent important targets in IPF given their role in initiating and driving aberrant wound healing responses that lead to excessive ECM deposition. Our objective was to examine a lipid nanoparticle (LNP)-based mRNA construct as a viable strategy to target alveolar epithelial cells and fibroblasts in IPF. mRNA-containing LNPs measuring ∼34 nm had …


Potassium-Selective Channelrhodopsins, Elena G Govorunova, Oleg A Sineshchekov, John L Spudich Mar 2023

Potassium-Selective Channelrhodopsins, Elena G Govorunova, Oleg A Sineshchekov, John L Spudich

Journal Articles

Since their discovery 21 years ago, channelrhodopsins have come of age and have become indispensable tools for optogenetic control of excitable cells such as neurons and myocytes. Potential therapeutic utility of channelrhodopsins has been proven by partial vision restoration in a human patient. Previously known channelrhodopsins are either proton channels, non-selective cation channels almost equally permeable to Na+ and K+ besides protons, or anion channels. Two years ago, we discovered a group of channelrhodopsins that exhibit over an order of magnitude higher selectivity for K+ than for Na+. These proteins, known as “kalium channelrhodopsins” or KCRs, lack the canonical tetrameric …