An official website of the United States government
Abstract The organization of membrane proteins between and within membrane-bound compartments is critical to cellular function. Yet we lack approaches to regulate this organization in a range of membrane-based materials, such as engineered cells, exosomes, and liposomes. Uncovering and leveraging biophysical drivers of membrane protein organization to design membrane systems could greatly enhance the functionality of these materials. Towards this goal, we use de novo protein design, molecular dynamic simulations, and cell-free systems to explore how membrane-protein hydrophobic mismatch could be used to tune protein cotranslational integration and organization in synthetic lipid membranes. We find that membranes must deform to accommodate membrane-protein hydrophobic mismatch, which reduces the expression and co-translational insertion of membrane proteins into synthetic membranes. We use this principle to sort proteins both between and within membranes, thereby achieving one-pot assembly of vesicles with distinct functions and controlled split-protein assembly, respectively. Our results shed light on protein organization in biological membranes and provide a framework to design self-organizing membrane-based materials with applications such as artificial cells, biosensors, and therapeutic nanoparticles.
more »
« less
Recent applications of fluorescence correlation spectroscopy in live cells
As a time-domain analogue of fluorescence imaging, FCS offers valuable insights into molecular dynamics, interactions, and concentrations within living cells. The primary insight generated by FCS is molecular mobility and concentration, which makes it useful for investigating molecular-scale details without the need for enrichment or separation. A specific strength of FCS is the ability to probe protein-protein interactions in live cells and several recent applications in this area are summarized. FCS is also used to investigate plasma membrane protein organization, with many applications to cell surface receptors and the mechanisms of drug binding. Finally, FCS is undergoing continual methodological innovations, such as imaging FCS, SPIM-FCS PIE-FCCS, STED-FCS, three-color FCS, and massively parallel FCS, which extend the capabilities to investigate molecular dynamics at different spatial and temporal scales. These innovations enable detailed examinations of cellular processes, including cellular transport and the spatial organization of membrane proteins.
more »
« less
- Award ID(s):
- 2308307
- PAR ID:
- 10550519
- Publisher / Repository:
- Current Opinion in Chemical Biology
- Date Published:
- Journal Name:
- Current Opinion in Chemical Biology
- Volume:
- 81
- Issue:
- C
- ISSN:
- 1367-5931
- Page Range / eLocation ID:
- 102480
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Specific lipid–protein interactions are key for cellular processes, and even more so for the replication of pathogens. The COVID-19 pandemic has drastically changed our lives and caused the death of nearly four million people worldwide, as of this writing. SARS-CoV-2 is the virus that causes the disease and has been at the center of scientific research over the past year. Most of the research on the virus is focused on key players during its initial attack and entry into the cellular host; namely the S protein, its glycan shield, and its interactions with the ACE2 receptors of human cells. As cases continue to rise around the globe, and new mutants are identified, there is an urgent need to understand the mechanisms of this virus during different stages of its life cycle. Here, we consider two integral membrane proteins of SARS-CoV-2 known to be important for viral assembly and infectivity. We have used microsecond-long all-atom molecular dynamics to examine the lipid–protein and protein–protein interactions of the membrane (M) and envelope (E) structural proteins of SARS-CoV-2 in a complex membrane model. We contrast the two proposed protein complexes for each of these proteins, and quantify their effect on their local lipid environment. This ongoing work also aims to provide molecular-level understanding of the mechanisms of action of this virus to possibly aid in the design of novel treatments.more » « less
-
A properly organized subcellular composition is essential to cell function. The canonical organizing principle within eukaryotic cells involves membrane-bound organelles; yet, such structures do not fully explain cellular complexity. Furthermore, discrete non-membrane-bound structures have been known for over a century. Liquid–liquid phase separation (LLPS) has emerged as a ubiquitous mode of cellular organization without the need for formal lipid membranes, with an ever-expanding and diverse list of cellular functions that appear to be regulated by this process. In comparison to traditional organelles, LLPS can occur across wider spatial and temporal scales and involves more distinct protein and RNA complexes. In this review, we discuss the impacts of LLPS on the organization of stem cells and their function during development. Specifically, the roles of LLPS in developmental signaling pathways, chromatin organization, and gene expression will be detailed, as well as its impacts on essential processes of asymmetric cell division. We will also discuss how the dynamic and regulated nature of LLPS may afford stem cells an adaptable mode of organization throughout the developmental time to control cell fate. Finally, we will discuss how aberrant LLPS in these processes may contribute to developmental defects and disease.more » « less
-
Abstract Fungal plasma membrane proteins represent key therapeutic targets for antifungal agents, yet their native structure and spatial distribution remain poorly characterized. Herein, we employ an integrative approach to investigate the organization of plasma membrane protein complexes inCandida glabrata, focusing on two abundant and essential membrane proteins, the β-(1,3)-glucan synthase (GS) and the proton pump Pma1. We show that treatment with caspofungin, an echinocandin antifungal that targets GS, disrupts the native distribution of membrane protein complexes and alters membrane biophysical properties. Perturbation of the sphingolipid biosynthesis further modulates drug susceptibility, revealing that the lipid environment plays an integral role in membrane protein organization and GS-echinocandin interactions. Our work highlights the importance of characterizing membrane proteins in their native context to understand their functions and inform the development of novel antifungal therapies.more » « less
-
ABSTRACT During Drosophila oogenesis, somatic follicle cells (FCs) differentiate to secrete components of the eggshell. Before secretion, the epithelium reorganizes to shape eggshell specializations, including border FC collective cell migration and later dorsal formation. These FC movements provide valuable insights into collective cell migration. However, little is known about centripetal migration, which encloses the oocyte after secretion has begun. Centripetal migration begins with apical extension of a few FCs that move away from the basement membrane to invade between germ cells. We define a timeline of reproducible milestones, using time-lapse imaging of egg chamber explants. Inward migration occurs in two phases. First, leading centripetal FCs ingress, extending apically over the anterior oocyte, and constricting basally. Second, following FCs move collectively toward the anterior, then around the corner to move inward with minimal change in aspect ratio. E-cadherin was required in leading centripetal FCs for their normal ingression, assessed with homozygous shotgun mutant or RNAi knockdown clones; ingression was influenced non-autonomously by mutant following FCs. This work establishes centripetal migration as an accessible model for biphasic E-cadherin-adhesion-mediated collective migration.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1016/j.cbpa.2024.102480
