Biology subjects

Baconguis, I.

Publications and source records attributed to Baconguis, I..

5 recordsLinked to original sources

bioRxiv2026

Differential Assembly of Native ENaC Complexes Across Mouse Epithelial Tissues

The epithelial sodium channel (ENaC) governs sodium and fluid absorption in the lung, kidney, and colon, but the organization of native ENaC complexes has remained difficult to define because of their low abundance and biochemical instability. To enable direct analysis of native assemblies, we generated a knock-in mouse in which the endogenous {gamma} subunit is fused at its C terminus to mVenus, a 3C protease cleavage site, and a 3xFLAG epitope (ENaC{gamma}-VF). The tag preserves physiological ENaC function, as ENaC{gamma}-VF mice display normal electrolyte handling, benzamil affinity, and amiloride-sensitive Na:K responses indistinguishable from wild-type animals. Using fluorescence-detection size-exclusion chromatography and single-molecule pull-down, we directly monitor intact native ENaC complexes from lung, kidney, and colon and uncover marked tissue-to-tissue differences in channel abundance and apparent complex size. Dual-color analysis with a fluorescent Fab against ENaC marks fully assembled {beta}{gamma} channels, while {gamma}-based fluorescence reports the broader population of {gamma}-containing assemblies. In combination, the ENaC{gamma}-VF line provides a biochemical anchor for identifying regulatory and trafficking proteins that co-purify with native ENaC complexes. These data show that ENaC architecture in vivo is heterogeneous, and establish ENaC{gamma}-VF mice as a platform for dissecting how epithelial environments shape ENaC assembly, composition, and regulation.

biochemistry↗

bioRxiv2024

Conformational plasticity of human acid-sensing ion channel 1a

Acid-sensing ion channels (ASICs) are typically activated by acidic environments and contribute to nociception and synaptic plasticity. ASIC1a is the most abundant subunit in the central nervous system and forms homomeric channels permeable to Na+ and Ca2+, making it a compelling therapeutic target for acidotic pathologies including stroke and traumatic brain injury. However, a complete conformational library of human ASIC1a in its various functional states has yet to be described. Using cryo-EM, we obtained hASIC1a structures across a pH range between 8.5 and 5.7, as well as in the presence of a toxin agonist and a gating-modulating mutation. We identify six major conformations that establish linear transmembrane helices to be associated with an open state, delineate mechanistic differences between proton and toxin activation, and demonstrate that desensitization leads to unexpected conformational diversity in the transmembrane domain. Together, they provide a three-dimensional rationalization of decades of structure-function studies on ASIC.

biochemistry↗

bioRxiv2024

Structural Insights into Subunit-Dependent Functional Regulation in Epithelial Sodium Channels

Epithelial sodium channels (ENaC) play a crucial role in Na+ reabsorption in mammals. To date, four subunits have been identified--, {beta}, {gamma}, and {delta}--believed to form different heteromeric complexes. Currently, only the structure of the {beta}{gamma} complex is known. To understand how these channels form with varying subunit compositions and define the contribution of each subunit to distinct properties, we co-expressed human {delta}, {beta}, and {gamma}. Using single-particle cryo-electron microscopy, we observed three distinct ENaC complexes. The structures unveil a pattern in which {beta} and {gamma} positions are conserved among the different complexes while the position in {beta}{gamma} trimer is occupied by either {delta} or another {beta}. The presence of {delta} induces structural rearrangements in the {gamma} subunit explaining the differences in channel activity observed between {beta}{gamma} and {delta}{beta}{gamma} channels. These structures define the mechanism by which ENaC subunit composition tunes ENaC function.

biochemistry↗

bioRxiv2023

Tweek-dependent formation of ER-PM contact sites enables astrocyte phagocytic function and remodeling of neurons

Neuronal remodeling generates an enormous amount of cellular debris, which is cleared from the nervous system by glia. At the larva-to-adult transition, Drosophila astrocytes transform into phagocytes and engulf degenerating larval synapses, axonal and dendritic debris. Here we show Tweek, a member of the bridge-like lipid transfer protein family, is upregulated in astrocytes as they ramp up their phagocytic function early in metamorphosis, and is essential for internalization and degradation of neuronal debris. Tweek forms a bridge between the endoplasmic reticulum (ER) and plasma membrane (PM), and loss of Tweek disrupts ER-PM contact formation and membrane lipid distribution. Patient-identified mutations in the human homolog associated with Alkuraya-Kucinskas syndrome resulted in similar defects in neuronal remodeling, indicating these are loss of function mutations. We propose Tweek helps establish and maintain ER-PM contacts during astrocyte phagocytic function and drives bulk lipid transfer to the plasma membrane for continued efficient internalization and degradation of neuronal debris.

neuroscience↗

bioRxiv2022

Appia: a web interface for chromatography

Chromatography is an essential family of assays for molecular biology and chemistry. Typically, only a qualitative assessment of peak height, position, and shape are sufficient to proceed. However, there are more advanced forms of chromatography that require integration of peak width, baseline subtraction, and precise peak position calling. To handle these precise workflows, instrument manufacturer software is complicated and arcane; this makes simpler day-to-day analyses inefficient. Additionally, each manufacturer reports the data in their own proprietary format, requiring that analysis is performed at instrument computers and making data sharing between labs difficult. Here we present Appia, a free, open-source chromatography processing and visualization package focused on making analysis, collaboration, and publication quick and easy.

biochemistry↗