scholarly journals Appoptosin interacts with mitochondrial outer-membrane fusion proteins and regulates mitochondrial morphology

2016 ◽  
Vol 129 (5) ◽  
pp. 994-1002 ◽  
Author(s):  
Cuilin Zhang ◽  
Zhun Shi ◽  
Lingzhi Zhang ◽  
Zehua Zhou ◽  
Xiaoyuan Zheng ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Fusion Proteins ◽  
Mitochondrial Outer Membrane ◽  
Mitochondrial Morphology ◽  
Membrane Fusion Proteins

Development of New Cloning Vectors for the Production of Immunogenic Outer Membrane Fusion Proteins in Escherichia coli

1996 ◽  
Vol 14 (2) ◽  
pp. 203-208 ◽  
Author(s):  
Pierre Cornells ◽  
Javier Cote Sierra ◽  
Antonio Lim ◽  
Achut Malur ◽  
Sumalee Tungpradabkul ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Fusion ◽  
Outer Membrane ◽  
Fusion Proteins ◽  
Cloning Vectors ◽  
Membrane Fusion Proteins

scholarly journals Localization and Regulation of the T1 Unimolecular Spanin

2018 ◽  
Vol 92 (22) ◽  
Author(s):  
Rohit Kongari ◽  
Jeffrey Snowden ◽  
Joel D. Berry ◽  
Ry Young
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Fusion Proteins ◽  
Transmembrane Domain ◽  
Time Lapse ◽  
Negative Regulator ◽  
Viral Fusion ◽  
Outer Membranes ◽  
Two Component ◽  
Membrane Fusion Proteins

ABSTRACTSpanins are bacteriophage lysis proteins responsible for disruption of the outer membrane, the final step of Gram-negative host lysis. The absence of spanins results in a terminal phenotype of fragile spherical cells. The phage T1 employs a unimolecular spanin gp11that has an N-terminal lipoylation signal and a C-terminal transmembrane domain. Upon maturation and localization, gp11ends up as an outer membrane lipoprotein with a C-terminal transmembrane domain embedded in the inner membrane, thus connecting both membranes as a covalent polypeptide chain. Unlike the two-component spanins encoded by most of the other phages, including lambda, the unimolecular spanins have not been studied extensively. In this work, we show that the gp11mutants lacking either membrane localization signal were nonfunctional and conferred a partially dominant phenotype. Translation from internal start sites within the gp11coding sequence generated a shorter product which exhibited a negative regulatory effect on gp11function. Fluorescence spectroscopy time-lapse videos of gp11-GFP expression showed gp11accumulated in distinct punctate foci, suggesting localized clusters assembled within the peptidoglycan meshwork. In addition, gp11was shown to mediate lysis in the absence of holin and endolysin function when peptidoglycan density was depleted by starvation for murein precursors. This result indicates that the peptidoglycan is a negative regulator of gp11function. This supports a model in which gp11acts by fusing the inner and outer membranes, a mode of action analogous to but mechanistically distinct from that proposed for the two-component spanin systems.IMPORTANCESpanins have been proposed to fuse the cytoplasmic and outer membranes during phage lysis. Recent work with the lambda spanins Rz-Rz1, which are similar to class I viral fusion proteins, has shed light on the functional domains and requirements for two-component spanin function. Here we report, for the first time, a genetic and biochemical approach to characterize unimolecular spanins, which are structurally and mechanistically different from two-component spanins. Considering similar predicted secondary structures within the ectodomains, unimolecular spanins can be regarded as a prokaryotic version of type II viral membrane fusion proteins. This study not only adds to our understanding of regulation of phage lysis at various levels but also provides a prokaryotic genetically tractable platform for interrogating class II-like membrane fusion proteins.

scholarly journals Bacterial Adaptor Membrane Fusion Proteins and the Structurally Dissimilar Outer Membrane Auxiliary Proteins Have Exchanged Central Domains inα-Proteobacteria

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Anthony Y. Xiao ◽  
Jing Wang ◽  
Milton H. Saier
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Fusion Proteins ◽  
Transport Systems ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Transporter Protein ◽  
Functional Implications ◽  
Membrane Fusion Proteins ◽  
Helical Region

Transport systems frequently include auxiliary proteins that perform subfunctions within the transporter protein complex. Two such proteins found in Gram-negative bacteria are the Membrane Fusion Proteins (MFPs) and the Outer Membrane Auxiliary (OMA) proteins. We here demonstrate that OMAs present inα-proteobacteria (but not in other bacterial types) contain a longα-helical region that is homologous to corresponding regions in the MFPs. The results suggest that during their evolution, OMAs, specifically fromα-proteobacteria, exchanged their ownα-helical domain for one derived from an MFP. The structural and functional implications of these findings are discussed.

scholarly journals Opening the Channel: the Two Functional Interfaces of Pseudomonas aeruginosa OpmH with the Triclosan Efflux Pump TriABC

2016 ◽  
Vol 198 (23) ◽  
pp. 3176-3185 ◽  
Author(s):  
Abigail T. Ntreh ◽  
Jon W. Weeks ◽  
Logan M. Nickels ◽  
Helen I. Zgurskaya
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Membrane Fusion ◽  
Outer Membrane ◽  
Fusion Proteins ◽  
Efflux Pump ◽  
Cell Envelope ◽  
Functional Integration ◽  
Content Type ◽  
Membrane Fusion Proteins ◽  
Stimulation Of

ABSTRACTTriABC-OpmH is an efflux pump fromPseudomonas aeruginosawith an unusual substrate specificity and protein composition. When overexpressed, this pump confers a high level of resistance to the biocide triclosan and the detergent SDS, which are commonly used in combinations for antimicrobial treatments. This activity requires an RND transporter (TriC), an outer membrane channel (OpmH), and two periplasmic membrane fusion proteins (TriA and TriB) with nonequivalent functions. In the active complex, TriA is responsible for the recruitment of OpmH, while TriB is responsible for stimulation of the transporter TriC. Here, we used the functional and structural differences between the two membrane fusion proteins to link their functional roles to specific interactions with OpmH. Our results provide evidence that the TriB-dependent stimulation of the TriC transporter is coupled to opening of the OpmH aperture through binding to the interprotomer groove of OpmH.IMPORTANCEMultidrug efflux transporters are important contributors to intrinsic and acquired antibiotic resistance in clinics. In Gram-negative bacteria, these transporters have a characteristic tripartite architecture spanning the entire two-membrane cell envelope. How such complexes are assembled and how the reactions separated in two different membranes are coupled to provide efficient efflux of various compounds across the cell envelope remain unclear. This study addressed these questions, and the results suggest a mechanism for functional integration of drug efflux by the inner membrane transporter and opening of the channel for transport across the outer membrane.

scholarly journals Ugo1 and Mdm30 act sequentially during Fzo1-mediated mitochondrial outer membrane fusion

2011 ◽  
Vol 124 (7) ◽  
pp. 1126-1135 ◽  
Author(s):  
F. Anton ◽  
J. M. Fres ◽  
A. Schauss ◽  
B. Pinson ◽  
G. J. K. Praefcke ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Outer Membrane ◽  
Mitochondrial Outer Membrane

scholarly journals Interdependent assembly of specific regulatory lipids and membrane fusion proteins into the vertex ring domain of docked vacuoles

2004 ◽  
Vol 167 (6) ◽  
pp. 1087-1098 ◽  
Author(s):  
Rutilio A. Fratti ◽  
Youngsoo Jun ◽  
Alexey J. Merz ◽  
Nathan Margolis ◽  
William Wickner
Keyword(s):  
Membrane Fusion ◽  
Protein Interactions ◽  
Fusion Proteins ◽  
Membrane Microdomains ◽  
Rab Gtpase ◽  
Protein Protein Interactions ◽  
Px Domain ◽  
Protein Partitioning ◽  
Membrane Fusion Proteins ◽  
Rab Effector

Membrane microdomains are assembled by lipid partitioning (e.g., rafts) or by protein–protein interactions (e.g., coated vesicles). During docking, yeast vacuoles assemble “vertex” ring-shaped microdomains around the periphery of their apposed membranes. Vertices are selectively enriched in the Rab GTPase Ypt7p, the homotypic fusion and vacuole protein sorting complex (HOPS)–VpsC Rab effector complex, SNAREs, and actin. Membrane fusion initiates at vertex microdomains. We now find that the “regulatory lipids” ergosterol, diacylglycerol and 3- and 4-phosphoinositides accumulate at vertices in a mutually interdependent manner. Regulatory lipids are also required for the vertex enrichment of SNAREs, Ypt7p, and HOPS. Conversely, SNAREs and actin regulate phosphatidylinositol 3-phosphate vertex enrichment. Though the PX domain of the SNARE Vam7p has direct affinity for only 3-phosphoinositides, all the regulatory lipids which are needed for vertex assembly affect Vam7p association with vacuoles. Thus, the assembly of the vacuole vertex ring microdomain arises from interdependent lipid and protein partitioning and binding rather than either lipid partitioning or protein interactions alone.

scholarly journals Membrane Fusion Proteins Are Required for oskar mRNA Localization in the Drosophila Egg Chamber

2000 ◽  
Vol 218 (2) ◽  
pp. 314-325 ◽  
Author(s):  
Douglas M Ruden ◽  
Vincent Sollars ◽  
Xiaoyan Wang ◽  
Daisuke Mori ◽  
Marina Alterman ◽  
...  
Keyword(s):  
Membrane Fusion ◽  
Fusion Proteins ◽  
Mrna Localization ◽  
Egg Chamber ◽  
Membrane Fusion Proteins

scholarly journals Virus membrane-fusion proteins: more than one way to make a hairpin

2006 ◽  
Vol 4 (1) ◽  
pp. 67-76 ◽  
Author(s):  
Margaret Kielian ◽  
Félix A. Rey
Keyword(s):  
Membrane Fusion ◽  
Fusion Proteins ◽  
Membrane Fusion Proteins

scholarly journals Regulation of mitochondrial fusion by the F-box protein Mdm30 involves proteasome-independent turnover of Fzo1

2006 ◽  
Vol 173 (5) ◽  
pp. 645-650 ◽  
Author(s):  
Mafalda Escobar-Henriques ◽  
Benedikt Westermann ◽  
Thomas Langer
Keyword(s):  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Critical Role ◽  
Mitochondrial Fusion ◽  
Yeast Cells ◽  
Mitochondrial Outer Membrane ◽  
Central Component ◽  
Mitochondrial Morphology ◽  
Proteolytic Pathway ◽  
F Box Protein

Mitochondrial morphology depends on balanced fusion and fission events. A central component of the mitochondrial fusion apparatus is the conserved GTPase Fzo1 in the outer membrane of mitochondria. Mdm30, an F-box protein required for mitochondrial fusion in vegetatively growing cells, affects the cellular Fzo1 concentration in an unknown manner. We demonstrate that mitochondrial fusion requires a tight control of Fzo1 levels, which is ensured by Fzo1 turnover. Mdm30 binds to Fzo1 and, dependent on its F-box, mediates proteolysis of Fzo1. Unexpectedly, degradation occurs along a novel proteolytic pathway not involving ubiquitylation, Skp1–Cdc53–F-box (SCF) E3 ubiquitin ligase complexes, or 26S proteasomes, indicating a novel function of an F-box protein. This contrasts to the ubiquitin- and proteasome-dependent turnover of Fzo1 in α-factor–arrested yeast cells. Our results therefore reveal not only a critical role of Fzo1 degradation for mitochondrial fusion in vegetatively growing cells but also the existence of two distinct proteolytic pathways for the turnover of mitochondrial outer membrane proteins.

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