Exploring protein import pores of cellular organelles at the single molecule level using the planar lipid bilayer technique

Harsman, Anke; Bartsch, Philipp; Hemmis, Birgit; Krüger, Vivien; Wagner, Richard

doi:10.1016/j.ejcb.2011.04.012

Cited by 23 publications

(24 citation statements)

References 94 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They are responsible for ATP production and oxidative phosphorylation, they are involved in cell survival, have a central role in ageing, participate in buffering of calcium ions, lipid metabolism and synthesis of iron-sulphur clusters (Murgia et al, 2009). A great majority of the mitochondrial proteins are responsible for the energy production synthesized in cytosol, so they have to be imported into mitochondria (Harsman et al, 2011).…”

Section: Mortalin and Mitochondriamentioning

confidence: 99%

Mortalin – a multipotent chaperone regulating cellular processes ranging from viral infection to neurodegeneration

Flachbartova¹,

Kováčech²

2013

View full text Add to dashboard Cite

Summary. -Heat shock 70kDa protein 9 (HSPA9)/mortalin is a heat-uninducible member of the heat shock 70 protein family. This protein has been attributed many cellular functions, including energy generation, stress response, carcinogenesis and involvement in neurodegenerative diseases, which is well documented by many names it has been given (CSA, MOT, MOT2, GRP75, PBP74, GRP-75, HSPA9B, MGC4500, MTHSP75, and mortalin). As an immortalization marker (hence the name "mortalin") in mouse embryonic fibroblasts cybrids it preferentially segregated with loss of immortality in passaged cells. Mortalin regulates the functions of the tumor suppressor protein p53 and plays important roles in stress response and maintenance of the mitochondria and endoplasmic reticulum. Furthermore, mortalin appears to have roles in membrane trafficking and viral release regulation, since it interacts with Nef protein it is necessary for secretion of exosomal negative factor (Nef) and HIV-1 virus release. Recently, mortalin has been described as a significant player in neurodegenerative diseases. Mutations in HSPA9 gene have been found in Parkinson΄s disease patients; mortalin isoform expression differs in hippocampus of patients with Alzheimer΄s disease and could regulate the β-amyloid toxicity pathway. In this review we summarize the functions of mortalin, its pathological implications in neuronal dysfunction and possible roles in neurodegenerative diseases.Keywords: HSPA9/mortalin/GRP75; mitochondria; cancer; Alzheimer΄s disease * Corresponding author: E-mail: Branislav.Kovacech@savba.sk; phone: +412-2-54788100. Abbreviations: Aβ = beta-amyloid; AD = Alzheimer΄s disease; PD = Parkinson΄s disease; HSPA9 = heat shock 70 kDa protein 9; Hsp = chaperone; MAC = membrane attack complex; Net = negative factor Contents:

show abstract

Section: Mortalin and Mitochondriamentioning

confidence: 99%

Mortalin – a multipotent chaperone regulating cellular processes ranging from viral infection to neurodegeneration

Flachbartova¹,

Kováčech²

2013

View full text Add to dashboard Cite

show abstract

“…The most critical component within the sandwich architecture of the bilayer chip is the material of the septum/foil and the characteristics of the aperture hole which serves as bilayer scaffold. Based on long term observations in our lab (>10 years [19,20]) we had to realize that for the fabrication, handling and long-term stability (>2 h) of the bilayers, the ratio of the diameter of the hole and the thickness of the supporting foil (aspect-ratio, ar) should not exceed a critical value of ~8 (ar ≤ 8). With respect to lipid annulus determined bilayer stability an aspect ratio of ar = 1 would be ideal, although, in practice, difficult to achieve [21].…”

Section: Resultsmentioning

confidence: 99%

Horizontal Bilayer for Electrical and Optical Recordings

et al. 2012

Self Cite

View full text Add to dashboard Cite

Artificial bilayer containing reconstituted ion channels, transporters and pumps serve as a well-defined model system for electrophysiological investigations of membrane protein structure–function relationship. Appropriately constructed microchips containing horizontally oriented bilayers with easy solution access to both sides provide, in addition, the possibility to investigate these model bilayer membranes and the membrane proteins therein with high resolution fluorescence techniques up to the single-molecule level. Here, we describe a bilayer microchip system in which long-term stable horizontal free-standing and hydrogel-supported bilayers can be formed and demonstrate its prospects particularly for single-molecule fluorescence spectroscopy and high resolution fluorescence microscopy in probing the physicochemical properties like phase behavior of the bilayer-forming lipids, as well as in functional studies of membrane proteins.

show abstract

“…S2) and reconstituted into liposomes. OEP40-proteoliposomes obtained from the different preparations were then assayed for channel activity using the planar bilayer system (21). After fusion of the OEP40 proteoliposomes with the planar bilayers, channel activity could be detected in all cases.…”

Section: Oep40 Forms a High Conductance Channel In Planar Lipidmentioning

confidence: 99%

“…Single channel analysis was performed essentially as described in detail in Ref. 21. In brief, we used the robust mean variance approach (22) that allows rigorous unbiased analysis of single channel recordings.…”

Section: Single Channel Recordings From Planar Lipid Bilayers Andmentioning

confidence: 99%

See 1 more Smart Citation

OEP40, a Regulated Glucose-permeable β-Barrel Solute Channel in the Chloroplast Outer Envelope Membrane

Harsman

Schock

Hemmis

et al. 2016

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Chloroplasts and mitochondria are unique endosymbiotic cellular organelles surrounded by two membranes. Essential metabolic networking between these compartments and their hosting cells requires the exchange of a large number of biochemical pathway intermediates in a directed and coordinated fashion across their inner and outer envelope membranes. Here, we describe the identification and functional characterization of a highly specific, regulated solute channel in the outer envelope of chloroplasts, named OEP40. Loss of OEP40 function in Arabidopsis thaliana results in early flowering under cold temperature. The reconstituted recombinant OEP40 protein forms a high conductance ␤-barrel ion channel with subconductant states in planar lipid bilayers. The OEP40 channel is slightly cation-selective P K؉ /P Cl؊ ≈ 4:1 and rectifying (ı ᠬ/ı ᠭ Х 2) with a slope conductance of Ḡ max Х 690 picosiemens. The OEP40 channel has a restriction zone diameter of Х1.4 nm and is permeable for glucose, glucose 1-phosphate and glucose 6-phosphate, but not for maltose. Moreover, channel properties are regulated by trehalose 6-phosphate, which cannot permeate. Altogether, our results indicate that OEP40 is a "glucose-gate" in the outer envelope membrane of chloroplasts, facilitating selective metabolite exchange between chloroplasts and the surrounding cell.The plant cell is highly compartmentalized, containing at least seven different types of organelles that are involved in metabolism and cellular maintenance. In many cases, metabolic pathways and other cellular processes are not confined to one organelle but require the cooperation of several of them, e.g. in protein secretion or photorespiration. Metabolic networking between compartments thus requires directed and coordinated exchange of biochemical pathway intermediates across organellar membranes (1). Chloroplasts and mitochondria are unique endosymbiotic cellular organelles, which like their prokaryotic ancestors are surrounded by two membranes. The inner membrane of both organelles is derived from the bacterial plasma membrane. Surprisingly, also the outer membrane largely originated from and still resembles the outer membrane of the Gram-negative-like bacterial endosymbiont (2). In the inner chloroplast envelope membrane (IE), 5 numerous metabolite transporter proteins were identified and characterized to large detail with respect to their physiological impact and molecular mechanisms (3). These transporters are hydrophobic, polytopic, and mainly ␣-helical membrane proteins facilitating the exchange of metabolic precursors, intermediates, and final products between plastids and the cytoplasm. In contrast, the characteristic channels of the outer membranes in bacteria, chloroplasts as well as mitochondria, span the membrane in the form of ␤-strands that are organized to form a barrel-like pore structure (4). Proteins sharing this three-dimensional arrangement were implied in a variety of functions, including protein import (5). In addition, solute pores like the voltage-dependen...

show abstract

Exploring protein import pores of cellular organelles at the single molecule level using the planar lipid bilayer technique

Cited by 23 publications

References 94 publications

Mortalin – a multipotent chaperone regulating cellular processes ranging from viral infection to neurodegeneration

Mortalin – a multipotent chaperone regulating cellular processes ranging from viral infection to neurodegeneration

Horizontal Bilayer for Electrical and Optical Recordings

OEP40, a Regulated Glucose-permeable β-Barrel Solute Channel in the Chloroplast Outer Envelope Membrane

Contact Info

Product

Resources

About