scholarly journals Molecular mechanism for kinesin-1 direct membrane recognition

2021 ◽  
Vol 7 (31) ◽  
pp. eabg6636
Author(s):  
Zuriñe Antón ◽  
Johannes F. Weijman ◽  
Christopher Williams ◽  
Edmund R. R. Moody ◽  
Judith Mantell ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Phylogenetic Analyses ◽  
Adaptor Proteins ◽  
Coincidence Detection ◽  
Organelle Transport ◽  
Splice Isoforms ◽  
Anionic Phospholipids ◽  
Direct Binding ◽  
Membrane Recognition

The cargo-binding capabilities of cytoskeletal motor proteins have expanded during evolution through both gene duplication and alternative splicing. For the light chains of the kinesin-1 family of microtubule motors, this has resulted in an array of carboxyl-terminal domain sequences of unknown molecular function. Here, combining phylogenetic analyses with biophysical, biochemical, and cell biology approaches, we identify a highly conserved membrane-induced curvature-sensitive amphipathic helix within this region of a subset of long kinesin light-chain paralogs and splice isoforms. This helix mediates the direct binding of kinesin-1 to lipid membranes. Membrane binding requires specific anionic phospholipids, and it contributes to kinesin-1–dependent lysosome positioning, a canonical activity that, until now, has been attributed exclusively the recognition of organelle-associated cargo adaptor proteins. This leads us to propose a protein-lipid coincidence detection framework for kinesin-1–mediated organelle transport.

scholarly journals Molecular mechanism for kinesin-1 direct membrane recognition

2021 ◽  
Author(s):  
Zuriñe Antón ◽  
Johannes F. Weijman ◽  
Christopher Williams ◽  
Edmund R.R. Moody ◽  
Judith Mantell ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Phylogenetic Analyses ◽  
Adaptor Proteins ◽  
Coincidence Detection ◽  
Organelle Transport ◽  
Splice Isoforms ◽  
Anionic Phospholipids ◽  
Direct Binding ◽  
Carboxy Terminal

AbstractThe cargo-binding capabilities of cytoskeletal motor proteins have expanded during evolution through both gene duplication and alternative splicing. For the light chains of the kinesin-1 family of microtubule motors, this has resulted in an array of carboxy-terminal domain sequences of unknown molecular function. Here, combining phylogenetic analyses with biophysical, biochemical and cell biology approaches we identify a highly conserved membrane-induced curvature-sensitive amphipathic helix within this region of a newly defined subset of long kinesin light chain paralogues and splice isoforms. This helix mediates the direct binding of kinesin-1 to lipid membranes. Membrane binding requires specific anionic phospholipids and is important for kinesin-1 dependent lysosome positioning, a canonical activity that until now has been attributed exclusively the recognition of organelle-associated cargo adaptor proteins. This leads us to propose a new protein-lipid coincidence detection framework for kinesin-1 mediated organelle transport.

ELECTROFUSION OF MODEL LIPID MEMBRANES VIEWED WITH HIGH TEMPORAL RESOLUTION

2006 ◽  
Vol 01 (04) ◽  
pp. 387-400 ◽  
Author(s):  
KARIN. A. RISKE ◽  
NATALYA BEZLYEPKINA ◽  
REINHARD LIPOWSKY ◽  
RUMIANA DIMOVA
Keyword(s):  
Electric Fields ◽  
Temporal Resolution ◽  
Lipid Membranes ◽  
Cell Biology ◽  
Digital Camera ◽  
Extensive Study ◽  
High Temporal Resolution ◽  
Giant Vesicles ◽  
Model Lipid Membranes ◽  
Millisecond Time Scale

The interaction of electric fields with lipid membranes and cells has been extensively studied in the last decades. The phenomena of electroporation and electrofusion are of particular interest because of their widespread use in cell biology and biotechnology. Giant vesicles, being of cell size and convenient for microscopy observations, are the simplest model of the cell membrane. However, optical microscopy observation of effects caused by electric DC pulses on giant vesicles is difficult because of the short duration of the pulse. Recently this difficulty has been overcome in our lab. Using a digital camera with high temporal resolution, we were able to access vesicle fusion dynamics on a sub-millisecond time scale. In this report, we present some observations on electrodeformation and –poration of single vesicles followed by an extensive study on the electrofusion of vesicle couples. Finally, we suggest an attractive approach for creating multidomain vesicles using electrofusion and present some preliminary results on the effect of membrane stiffness on the fusion dynamics.

scholarly journals The Role of Alternative RNA Splicing in the Regulation of hTERT, Telomerase, and Telomeres: Implications for Cancer Therapeutics

Cancers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1514 ◽  
Author(s):  
Aaron L. Slusher ◽  
Jeongjin JJ Kim ◽  
Andrew T. Ludlow
Keyword(s):  
Cancer Cell ◽  
Rna Splicing ◽  
Cell Biology ◽  
Science Studies ◽  
De Novo ◽  
Treatment Strategies ◽  
Cancer Therapeutics ◽  
Telomerase Activity ◽  
Splice Isoforms ◽  
Alternatively Spliced

Alternative RNA splicing impacts the majority (>90%) of eukaryotic multi-exon genes, expanding the coding capacity and regulating the abundance of gene isoforms. Telomerase (hTERT) is a key example of a gene that is alternatively spliced during human fetal development and becomes dysregulated in nearly all cancers. Approximately 90% of human tumors use telomerase to synthesize de novo telomere repeats and obtain telomere-dependent cellular immortality. Paradigm shifting data indicates that hTERT alternative splicing, in addition to transcription, plays an important role in the regulation of active telomerase in cells. Our group and others are pursuing the basic science studies to progress this emerging area of telomerase biology. Recent evidence demonstrates that switching splicing of hTERT from the telomerase activity producing full-length hTERT isoform to alternatively spliced, non-coding isoforms may be a novel telomerase inhibition strategy to prevent cancer growth and survival. Thus, the goals of this review are to detail the general roles of telomerase in cancer development, explore the emerging regulatory mechanisms of alternative RNA splicing of the hTERT gene in various somatic and cancer cell types, define the known and potential roles of hTERT splice isoforms in cancer cell biology, and provide insight into new treatment strategies targeting hTERT in telomerase-positive cancers.

scholarly journals The autophagy protein Ambra1 regulates gene expression by supporting novel transcriptional complexes

2020 ◽  
Vol 295 (34) ◽  
pp. 12045-12057
Author(s):  
Christina Schoenherr ◽  
Adam Byron ◽  
Billie Griffith ◽  
Alexander Loftus ◽  
Jimi C. Wills ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cancer Cell ◽  
Cell Invasion ◽  
Cell Biology ◽  
Protein Complexes ◽  
Transcriptional Regulators ◽  
Adaptor Proteins ◽  
Nuclear Pore ◽  
Biochemical Fractionation

Ambra1 is considered an autophagy and trafficking protein with roles in neurogenesis and cancer cell invasion. Here, we report that Ambra1 also localizes to the nucleus of cancer cells, where it has a novel nuclear scaffolding function that controls gene expression. Using biochemical fractionation and proteomics, we found that Ambra1 binds to multiple classes of proteins in the nucleus, including nuclear pore proteins, adaptor proteins such as FAK and Akap8, chromatin-modifying proteins, and transcriptional regulators like Brg1 and Atf2. We identified biologically important genes, such as Angpt1, Tgfb2, Tgfb3, Itga8, and Itgb7, whose transcription is regulated by Ambra1-scaffolded complexes, likely by altering histone modifications and Atf2 activity. Therefore, in addition to its recognized roles in autophagy and trafficking, Ambra1 scaffolds protein complexes at chromatin, regulating transcriptional signaling in the nucleus. This novel function for Ambra1, and the specific genes impacted, may help to explain the wider role of Ambra1 in cancer cell biology.

scholarly journals Rosistilla oblonga gen. nov., sp. nov. and Rosistilla carotiformis sp. nov., isolated from biotic or abiotic surfaces in Northern Germany, Mallorca, Spain and California, USA

2020 ◽  
Vol 113 (12) ◽  
pp. 1939-1952 ◽  
Author(s):  
Muhammad Waqqas ◽  
Markus Salbreiter ◽  
Nicolai Kallscheuer ◽  
Mareike Jogler ◽  
Sandra Wiegand ◽  
...  
Keyword(s):  
Cell Biology ◽  
Novel Species ◽  
Phylogenetic Analyses ◽  
Optimal Growth ◽  
The Novel ◽  
Biological Features ◽  
Abiotic Surfaces ◽  
The Family ◽  
Axenic Cultures ◽  
The Baltic

AbstractPlanctomycetes are ubiquitous bacteria with fascinating cell biological features. Strains available as axenic cultures in most cases have been isolated from aquatic environments and serve as a basis to study planctomycetal cell biology and interactions in further detail. As a contribution to the current collection of axenic cultures, here we characterise three closely related strains, Poly24T, CA51T and Mal33, which were isolated from the Baltic Sea, the Pacific Ocean and the Mediterranean Sea, respectively. The strains display cell biological features typical for related Planctomycetes, such as division by polar budding, presence of crateriform structures and formation of rosettes. Optimal growth was observed at temperatures of 30–33 °C and at pH 7.5, which led to maximal growth rates of 0.065–0.079 h−1, corresponding to generation times of 9–11 h. The genomes of the novel isolates have a size of 7.3–7.5 Mb and a G + C content of 57.7–58.2%. Phylogenetic analyses place the strains in the family Pirellulaceae and suggest that Roseimaritima ulvae and Roseimaritima sediminicola are the current closest relatives. Analysis of five different phylogenetic markers, however, supports the delineation of the strains from members of the genus Roseimaritima and other characterised genera in the family. Supported by morphological and physiological differences, we conclude that the strains belong to the novel genus Rosistilla gen. nov. and constitute two novel species, for which we propose the names Rosistilla carotiformis sp. nov. and Rosistilla oblonga sp. nov. (the type species). The two novel species are represented by the type strains Poly24T (= DSM 102938T = VKM B-3434T = LMG 31347T = CECT 9848T) and CA51T (= DSM 104080T = LMG 29702T), respectively.

scholarly journals Atomic-resolution structure of the CAP-Gly domain of dynactin on polymeric microtubules determined by magic angle spinning NMR spectroscopy

2015 ◽  
Vol 112 (47) ◽  
pp. 14611-14616 ◽  
Author(s):  
Si Yan ◽  
Changmiao Guo ◽  
Guangjin Hou ◽  
Huilan Zhang ◽  
Xingyu Lu ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Cell Biology ◽  
Double Resonance ◽  
Magic Angle Spinning ◽  
Atomic Resolution ◽  
Organelle Transport ◽  
Magic Angle ◽  
Associated Proteins ◽  
Angle Spinning ◽  
Resolution Structure

Microtubules and their associated proteins perform a broad array of essential physiological functions, including mitosis, polarization and differentiation, cell migration, and vesicle and organelle transport. As such, they have been extensively studied at multiple levels of resolution (e.g., from structural biology to cell biology). Despite these efforts, there remain significant gaps in our knowledge concerning how microtubule-binding proteins bind to microtubules, how dynamics connect different conformational states, and how these interactions and dynamics affect cellular processes. Structures of microtubule-associated proteins assembled on polymeric microtubules are not known at atomic resolution. Here, we report a structure of the cytoskeleton-associated protein glycine-rich (CAP-Gly) domain of dynactin motor on polymeric microtubules, solved by magic angle spinning NMR spectroscopy. We present the intermolecular interface of CAP-Gly with microtubules, derived by recording direct dipolar contacts between CAP-Gly and tubulin using double rotational echo double resonance (dREDOR)-filtered experiments. Our results indicate that the structure adopted by CAP-Gly varies, particularly around its loop regions, permitting its interaction with multiple binding partners and with the microtubules. To our knowledge, this study reports the first atomic-resolution structure of a microtubule-associated protein on polymeric microtubules. Our approach lays the foundation for atomic-resolution structural analysis of other microtubule-associated motors.

Digression on Membrane Electroporation for Drug and Gene Delivery

2002 ◽  
Vol 1 (5) ◽  
pp. 329-339 ◽  
Author(s):  
Eberhard Neumann ◽  
Sergej Kakorin
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Cell Transformation ◽  
Single Cells ◽  
Surface Membrane ◽  
Quantitative Description ◽  
Lipid Vesicles ◽  
General Chemical ◽  
Membrane Rigidity ◽  
Medical Disciplines

Membrane electroporation (ME) defines an electrical technique to render lipid membranes porous and permeable, transiently and reversibly, by external voltage pulses. Although there are numerous applications of ME to manipulate cells, organelles and tissues in cell biology, biotechnology and medicine, yet the molecular mechanism of ME is only slowly being understood. A general chemical-thermodynamical approach for the quantitative description of cell membrane electroporation has been developed to provide the framework to quantitatively rationalize electroporative cell transformation and electroporative uptake of drug-like dyes into cells, as well as electrolyte efflux from salt-filled electroporated vesicles. Mechanistically, the electroporative transfer of gene and drug-like dyes involves the coupling between an interactive contact formation of the permeates with the cell surface membrane and the structural electroporation-resealing cycle [Formula: see text] where C is the closed and (P) represents a number of different porated membrane states, respectively. The experimentally accessible concentration fraction fp = [(P)] /([C] + [(P)]) of porous states is related to thermodynamic and electro-mechanic parameters such as temperature and the electric field strength, membrane rigidity or curvature. The results of the theoretical approach, mainly based on electrooptical data of lipid vesicles, have been successfully used to analyze single cells and to specify conditions for the practical purpose of direct electroporative gene transfer and drug delivery, in particular in the new medical disciplines of electroporative chemotherapy and electroporative gene vaccination.

scholarly journals Cholesterol and anionic phospholipids increase the binding of amyloidogenic transthyretin to lipid membranes

2008 ◽  
Vol 1778 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Xu Hou ◽  
Adam Mechler ◽  
Lisandra L. Martin ◽  
Marie-Isabel Aguilar ◽  
David H. Small
Keyword(s):  
Lipid Membranes ◽  
Anionic Phospholipids

Ligand-Receptor Contact Interactions Using Self-Assembled Bilayer Lipid Membranes

1994 ◽  
Vol 360 ◽  
Author(s):  
A. Leitmannova Ottova ◽  
H. Ti Tien
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Bilayer Lipid Membranes ◽  
Contact Interactions ◽  
Bilayer Lipid ◽  
Ion Sensing ◽  
Research Areas ◽  
Self Assembled ◽  
Antigen Antibody

AbstractBiological membranes play a crucial role in signal transduction and information processing as well as in energy conversion. This is owing to the fact that most physiological activities involve some kind of lipid bilayer-based receptor-ligand contact interactions. There are many outstanding examples such as ion sensing, antigen-antibody binding, and ligand/voltage--gated channels, to name a few. One approach to study these interactions in vitro is facilitated by employing artificial bilayer lipid membranes (BLMs). We have focused the efforts on ion and/or molecular selectivity and specificity using newly available self-assembled BLMs on solid support (i.e., s-BLMs), whose enhanced stability greatly aids in research areas of membrane biochemistry, biophysics and cell biology as well as in biosensor designs and molecular devices development. In this paper, our current work along with the experiments carried out in close collaboration with others on s-BLMs will be presented.

scholarly journals Direct binding of phosphatidylglycerol at specific sites modulates desensitization of a ligand-gated ion channel

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Ailing Tong ◽  
John T Petroff ◽  
Fong-Fu Hsu ◽  
Philipp AM Schmidpeter ◽  
Crina M Nimigean ◽  
...  
Keyword(s):  
Ion Channel ◽  
Transmembrane Domain ◽  
Native Mass Spectrometry ◽  
Coarse Grained ◽  
Specific Lipids ◽  
Anionic Phospholipid ◽  
Anionic Phospholipids ◽  
Functional Assays ◽  
Direct Binding ◽  
Dynamics Simulations

Pentameric ligand-gated ion channels (pLGICs) are essential determinants of synaptic transmission, and are modulated by specific lipids including anionic phospholipids. The exact modulatory effect of anionic phospholipids in pLGICs and the mechanism of this effect are not well understood. Using native mass spectrometry, coarse-grained molecular dynamics simulations and functional assays, we show that the anionic phospholipid, 1-palmitoyl-2-oleoyl phosphatidylglycerol (POPG), preferentially binds to and stabilizes the pLGIC, Erwinia ligand-gated ion channel (ELIC), and decreases ELIC desensitization. Mutations of five arginines located in the interfacial regions of the transmembrane domain (TMD) reduce POPG binding, and a subset of these mutations increase ELIC desensitization. In contrast, a mutation that decreases ELIC desensitization, increases POPG binding. The results support a mechanism by which POPG stabilizes the open state of ELIC relative to the desensitized state by direct binding at specific sites.

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