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Inner membrane protein

Chao-Chen Lin, Hsin-Fang Hsu, Peter Jomo Walla
The fusion of two opposing membranes is essential in biological functions such as fertilization, viral entry, membrane trafficking and synaptic transmission. Before the membrane bilayers are fully connected, at some stage a hemifusion intermediate-when the outer leaflets are merged but not the inner leaflets-is formed. However, the position of hemifusion in the energy landscape and the duration of it vary and have not been fully mapped out. To date, there has not been a way to differentiate lipid mixing of the two leaflets directly in a single experiment...
October 20, 2016: Journal of Physical Chemistry. B
Emilie Lukasova, Aleš Kovařík, Alena Bačíková, Martin Falk, Stanislav Kozubek
The cellular transition to senescence is associated with extensive chromatin reorganization and gene expression changes. Recent studies appeared implying an association of lamin B1 (LB1) reduction with chromatin rearrangement in human fibroblasts promoted to senescence, while the mechanisms and structural features of these relations were not yet clarified. In this work we examined the functions of LB1 and lamin B receptor (LBR) in human cancer cells. We found that both LB1 and LBR tend to deplete during cancer cells transfer to senescence by γ-irradiation...
October 19, 2016: Biochemical Journal
Vojtěch Žárský, Pavel Doležal
BACKGROUND: The Tim17 family of proteins plays a fundamental role in the biogenesis of mitochondria. Three Tim17 family proteins, Tim17, Tim22, and Tim23, are the central components of the widely conserved multi-subunit protein translocases, TIM23 and TIM22, which mediate protein transport across and into the inner mitochondrial membrane, respectively. In addition, several Tim17 family proteins occupy the inner and outer membranes of plastids. RESULTS: We have performed comprehensive sequence analyses on 5631 proteomes from all domains of life deposited in the Uniprot database...
October 19, 2016: Biology Direct
Maite L Ortiz-Suarez, Firdaus Samsudin, Thomas J Piggot, Peter J Bond, Syma Khalid
OmpA is a multidomain protein found in the outer membranes of most Gram-negative bacteria. Despite a wealth of reported structural and biophysical studies, the structure-function relationships of this protein remain unclear. For example, it is still debated whether it functions as a pore, and the precise molecular role it plays in attachment to the peptidoglycan of the periplasm is unknown. The absence of a consensus view is partly due to the lack of a complete structure of the full-length protein. To address this issue, we performed molecular-dynamics simulations of the full-length model of the OmpA dimer proposed by Robinson and co-workers...
October 18, 2016: Biophysical Journal
Jeevan B Gc, Bernard S Gerstman, Robert V Stahelin, Prem P Chapagain
The Ebola virus is a lipid-enveloped virus that obtains its lipid coat from the plasma membrane of the host cell it infects during the budding process. The Ebola virus protein VP40 localizes to the inner leaflet of the plasma membrane and forms the viral matrix, which provides the major structure for the Ebola virus particles. VP40 is initially a dimer that rearranges to a hexameric structure that mediates budding. VP40 hexamers and larger filaments have been shown to be stabilized by PI(4,5)P2 in the plasma membrane inner leaflet...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Andrzej M Woyda-Ploszczyca, Wieslawa Jarmuszkiewicz
Uncoupling proteins (UCPs) belong to the mitochondrial anion carrier protein family and mediate regulated proton leak across the inner mitochondrial membrane. Free fatty acids, aldehydes such as hydroxynonenal, and retinoids activate UCPs. However, there are some controversies about the effective action of retinoids and aldehydes alone; thus, only free fatty acids are commonly accepted positive effectors of UCPs. Conversely, purine nucleotides such as GTP inhibit UCP-mediated mitochondrial proton leak. In turn, membranous coenzyme Q may play a role as a redox state-dependent metabolic sensor that modulates the complete activation/inhibition of UCPs...
October 14, 2016: Biochimica et Biophysica Acta
Laura M Faure, Jean-Bernard Fiche, Leon Espinosa, Adrien Ducret, Vivek Anantharaman, Jennifer Luciano, Sébastien Lhospice, Salim T Islam, Julie Tréguier, Mélanie Sotes, Erkin Kuru, Michael S Van Nieuwenhze, Yves V Brun, Olivier Théodoly, Aravind L, Marcelo Nollmann, Tâm Mignot
Various rod-shaped bacteria mysteriously glide on surfaces in the absence of appendages such as flagella or pili. In the deltaproteobacterium Myxococcus xanthus, a putative gliding motility machinery (Agl-Glt) localizes to so-called Focal Adhesion sites (FA) that form stationary contact points with the underlying surface. We discovered that the Agl-Glt machinery contains an inner-membrane motor complex that moves intracellularly along a right-handed helical path, and when it becomes stationary at FA sites, it powers a left-handed rotation of the cell around its long axis...
October 5, 2016: Nature
Kyosei Urafuji, Manabu Arioka
In mammals, three types of intracellular phospholipase A1 (iPLA1) enzymes have been characterized and are thought to be involved in various cellular processes such as phospholipid metabolism, organelle biogenesis, and membrane trafficking. In this study we analyzed the unique iPLA1-like protein, Yor022c, in the budding yeast Saccharomyces cerevisiae. By the mass spectrometry analysis, we demonstrate that Yor022c is actually a phospholipase displaying sn-1-specific activity toward phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid, generating 2-acyl lysophospholipids...
October 13, 2016: Biochemical and Biophysical Research Communications
Timothy Wai, Shotaro Saita, Hendrik Nolte, Sebastian Müller, Tim König, Ricarda Richter-Dennerlein, Hans-Georg Sprenger, Joaquin Madrenas, Mareike Mühlmeister, Ulrich Brandt, Marcus Krüger, Thomas Langer
The SPFH (stomatin, prohibitin, flotillin, HflC/K) superfamily is composed of scaffold proteins that form ring-like structures and locally specify the protein-lipid composition in a variety of cellular membranes. Stomatin-like protein 2 (SLP2) is a member of this superfamily that localizes to the mitochondrial inner membrane (IM) where it acts as a membrane organizer. Here, we report that SLP2 anchors a large protease complex composed of the rhomboid protease PARL and the i-AAA protease YME1L, which we term the SPY complex (for SLP2-PARL-YME1L)...
October 13, 2016: EMBO Reports
Shaoxiao Wang, Siyuan Zhang, Chuan Xu, Addie Barron, Floyd Galiano, Dhaval Patel, Yong Joo Lee, Guy A Caldwell, Kim A Caldwell, Stephan N Witt
We have been investigating the role that phosphatidylethanolamine (PE) and phosphatidylcholine (PC) content plays in modulating the solubility of the Parkinson's disease protein alpha-synuclein (α-syn) using Saccharomyces cerevisiae and Caenorhabditis elegans. One enzyme that synthesizes PE is the conserved enzyme phosphatidylserine decarboxylase (Psd1/yeast; PSD-1/worms), which is lodged in the inner mitochondrial membrane. We previously found that decreasing the level of PE due to knockdown of Psd1/psd-1 affects the homeostasis of α-syn in vivo...
2016: PloS One
Daniel Köhler, Stefan Helm, Birgit Agne, Sacha Baginsky
Toc159-containing complexes at the outer chloroplast envelope membrane form stable super-complexes with a 1-MDa translocon at the inner chloroplast envelope membrane of which Tic56 is one essential subunit. While the single mutants tic56-1 and ppi2 (toc159) have an albino phenotype and are able to grow heterotrophically, we find the double mutant to be embryo-lethal. Comprehensive quantitative proteome profiling with both single mutants in combination with GeneChip analyses identified a posttranscriptional defect in the accumulation of plastid ribosomal proteins and diminished expression of plastid encoded proteins...
October 12, 2016: Plant Physiology
Brant M Webster, David J Thaller, Jens Jäger, Sarah E Ochmann, Sapan Borah, C Patrick Lusk
The integrity of the nuclear envelope barrier relies on membrane remodeling by the ESCRTs, which seal nuclear envelope holes and contribute to the quality control of nuclear pore complexes (NPCs); whether these processes are mechanistically related remains poorly defined. Here, we show that the ESCRT-II/III chimera, Chm7, is recruited to a nuclear envelope subdomain that expands upon inhibition of NPC assembly and is required for the formation of the storage of improperly assembled NPCs (SINC) compartment. Recruitment to sites of NPC assembly is mediated by its ESCRT-II domain and the LAP2-emerin-MAN1 (LEM) family of integral inner nuclear membrane proteins, Heh1 and Heh2...
October 12, 2016: EMBO Journal
Úrsula Flores-Pérez, Paul Jarvis
Chloroplasts are structurally complex organelles containing ~2000-3000 proteins. They are delimited by a double membrane system or envelope, have an inner aqueous compartment called the stroma, and possess a second internal membrane system called the thylakoids. Thus, determining the suborganellar location of a chloroplast protein is vital to understanding or verifying its function. One way in which protein localization can be addressed is through fractionation. Here we present two rapid and simple methods that may be applied sequentially on the same day: (a) The isolation of intact chloroplasts from Arabidopsis thaliana plants that may be used directly (e...
2017: Methods in Molecular Biology
Nicola Strenzke, Rituparna Chakrabarti, Hanan Al-Moyed, Alexandra Müller, Gerhard Hoch, Tina Pangrsic, Gulnara Yamanbaeva, Christof Lenz, Kuan-Ting Pan, Elisabeth Auge, Ruth Geiss-Friedlander, Henning Urlaub, Nils Brose, Carolin Wichmann, Ellen Reisinger
The multi-C2 domain protein otoferlin is required for hearing and mutated in human deafness. Some OTOF mutations cause a mild elevation of auditory thresholds but strong impairment of speech perception. At elevated body temperature, hearing is lost. Mice homozygous for one of these mutations, Otof(I515T/I515T), exhibit a moderate hearing impairment involving enhanced adaptation to continuous or repetitive sound stimulation. In Otof(I515T/I515T) inner hair cells (IHCs), otoferlin levels are diminished by 65%, and synaptic vesicles are enlarged...
October 11, 2016: EMBO Journal
Sophie Le Page, Marjorie Niro, Jérémy Fauconnier, Laura Cellier, Sophie Tamareille, Abdallah Gharib, Arnaud Chevrollier, Laurent Loufrani, Céline Grenier, Rima Kamel, Emmanuelle Sarzi, Alain Lacampagne, Michel Ovize, Daniel Henrion, Pascal Reynier, Guy Lenaers, Delphine Mirebeau-Prunier, Fabrice Prunier
BACKGROUND: Recent data suggests the involvement of mitochondrial dynamics in cardiac ischemia/reperfusion (I/R) injuries. Whilst excessive mitochondrial fission has been described as detrimental, the role of fusion proteins in this context remains uncertain. OBJECTIVES: To investigate whether Opa1 (protein involved in mitochondrial inner-membrane fusion) deficiency affects I/R injuries. METHODS AND RESULTS: We examined mice exhibiting Opa1delTTAG mutations (Opa1+/-), showing 70% Opa1 protein expression in the myocardium as compared to their wild-type (WT) littermates...
2016: PloS One
Tongtao Yue, Shixin Li, Yan Xu, Xianren Zhang, Fang Huang
The receptor mediated endocytosis of nanoparticles (NPs) is known to be size and shape dependent but regulated by membrane properties, like tension, rigidity and especially membrane proteins. Compared with transmembrane receptors which directly bind ligands coated on NPs to provide the driving force for passive endocytosis, the hidden role of inner anchored membrane proteins (IAMPs), however, has been grossly neglected. Here, by applying the N-varied dissipative particle dynamics (DPD) techniques, we present the first simulation study on the interplay between wrapping of NPs and clustering of IAMPs...
October 10, 2016: Journal of Physical Chemistry. B
Chih-Chan Lin, Chia-Lang Fang, Ding-Ping Sun, You-Cheng Hseu, Yih-Huei Uen, Kai-Yuan Lin, Yung-Chang Lin
BACKGROUND/PURPOSE: Gastric cancer (GC) is one of the most common malignant cancers worldwide. However, little is known about the molecular process underlying this disease and its progression. This study investigated correlations between the expression of a mitochondrial inner membrane protein translocase of inner mitochondrial membrane 9 homolog (TIMM9) and various clinicopathologic parameters as well as patients' survival. METHODS: Gastric tissue samples were obtained from 140 patients with GC and expression levels of TIMM9 were analyzed through immunohistochemistry...
October 6, 2016: Journal of the Formosan Medical Association, Taiwan Yi Zhi
Devinder Sandhu, Taylor Atkinson, Andrea Noll, Callie Johnson, Katherine Espinosa, Jessica Boelter, Stephanie Abel, Balpreet K Dhatt, Terese Barta, Eric Singsaas, Sol Sepsenwol, A Susana Goggi, Reid G Palmer
We have identified a viable-yellow and a lethal-yellow chlorophyll-deficient mutant in soybean. Segregation patterns suggested single-gene recessive inheritance for each mutant. The viable- and lethal-yellow plants showed significant reduction of chlorophyll a and b. Photochemical energy conversion efficiency and photochemical reflectance index were reduced in the viable-yellow plants relative to the wildtype, whereas the lethal-yellow plants showed no electron transport activity. The viable-yellow plants displayed reduced thylakoid stacking, while the lethal-yellow plants exhibited failure of proplastid differentiation into normal chloroplasts with grana...
November 2016: Plant Science: An International Journal of Experimental Plant Biology
Leïla Zerkoune, Sylviane Lesieur, Jean-Luc Putaux, Luc Choisnard, Annabelle Gèze, Denis Wouessidjewe, Borislav Angelov, Corinne Vebert-Nardin, James Doutch, Angelina Angelova
Soft mesoporous hierarchically structured particles were created by the self-assembly of an amphiphilic deep cavitand cyclodextrin βCD-nC10 (degree of substitution n = 7.3), with a nanocavity grafted by multiple alkyl (C10) chains on the secondary face of the βCD macrocycle through enzymatic biotransesterification, and the nonlamellar lipid monoolein (MO). The effect of the non-ionic dispersing agent polysorbate 80 (P80) on the liquid crystalline organization of the nanocarriers and their stability was studied in the context of vesicle-to-cubosome transition...
September 13, 2016: Soft Matter
Inge Leonie Van 't Veer, Nadia Leloup, Alexander Egan, Bert Janssen, Nathaniel Martin, Waldemar Vollmer, Eefjan Breukink
Surface Plasmon Resonance (SPR) is one of the most powerful label free methods to determine kinetic parameters of molecular interactions in real time and in a high sensitive way. Penicillin binding proteins (PBPs) are peptidoglycan synthesis enzymes present in most bacteria. The established protocols to analyze interactions of PBPs by SPR involves immobilization to an ampicillin coated chip surface, a β-lactam antibiotic mimicking its substrate, forming a covalent complex with the PBPs transpeptidase (TP) active site...
October 6, 2016: Chembiochem: a European Journal of Chemical Biology
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