Role of disulfide bonds in maintaining the structural integrity of the sheath of Leptothrix discophora SP-6.

Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.

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The effect of oestrogen withdrawal on cardiac Ca2+ regulation and the influence of GPER1

European Heart Journal ◽

10.1093/ehjci/ehaa946.3599 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

A.J Francis ◽

J.M Firth ◽

N Islam ◽

J Gorelik ◽

K.T MacLeod

Keyword(s):

Heart Failure ◽

Structural Integrity ◽

Left Ventricular ◽

Funding Source ◽

Hormonal Changes ◽

Ion Conductance ◽

Developing Heart ◽

Rapid Stimulation ◽

Post Menopausal

Abstract Background Post-menopausal women have an enhanced risk of developing heart failure, attributed to declining oestrogen levels during menopause. However, the signalling mechanisms remain undetermined. Purpose We aim to determine the role of G-protein coupled oestrogenic receptor 1 (GPER1) in intracellular Ca2+ regulation and the consequences of hormonal changes that may exacerbate the pathophysiology of heart failure. Methods Ovariectomy (OVx) (mimics menopausal hormone changes) or sham surgeries were conducted on female guinea pigs. Left ventricular cardiomyocytes were isolated 150-days post-operatively for experimental use. Cellular t-tubule network and structural integrity was measured using fluorescent di-8-ANEPPs staining and scanning ion conductance microscopy. GPER1 expression and localisation was measured by Western blot and immunostaining. The role of GPER1 activation was measured using selective agonist G-1 in electrophysiological and Ca2+-sensitive dye fluorescence experiments. Results Following oestrogen withdrawal, the t-tubule network density decreased by 13% and z-groove index reduced by 15%. GPER1 predominantly localised to the peri-nuclear endoplasmic reticulum and its expression increased by 32% in OVx. Action potential duration (APD) prolonged in OVx and following GPER1 activation, APD90 shortened by 11% and 25% in sham and OVx respectively. OVx cells had larger peak inward Ca2+ current (ICaL) (by 22%) and sarcoplasmic reticulum (SR) Ca2+ content (by 13%), compared with sham. While GPER1 activation had little effect on peak ICaL or SR content, it reduced Ca2+ transient amplitude (by 20%), SR fractional release (by 11%) in OVx cells. The frequency of occurrence of spontaneous Ca2+ waves evoked by periods of rapid stimulation reduced by 40% and wave-free survival time prolonged in OVx cells following GPER1 activation. Conclusions In the hearts of an animal species whose electrophysiology and intracellular Ca2+ regulation is akin to humans, we show that following oestrogen deficiency, the t-tubule network is down-regulated and becomes disorganised, GPER1 expression is increased and its activation induces negative inotropic responses in cardiomyocytes. This may limit the adverse changes to Ca2+ signalling reported in OVx that could be pro-arrhythmic and exacerbate the progression to heart failure. Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): British Heart Foundation

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Folding of peptides and proteins: role of disulfide bonds, recent developments

BioMolecular Concepts ◽

10.1515/bmc-2013-0022 ◽

2013 ◽

Vol 4 (6) ◽

pp. 597-604 ◽

Cited By ~ 8

Author(s):

Yuji Hidaka ◽

Shigeru Shimamoto

Keyword(s):

Protein Folding ◽

Disulfide Bonds ◽

Bond Formation ◽

Difficult Problem ◽

Chemical Methods ◽

Mutant Proteins ◽

Folding Intermediates ◽

Peptide Chemistry ◽

Recent Developments

AbstractDisulfide-containing proteins are ideal models for studies of protein folding as the folding intermediates can be observed, trapped, and separated by HPLC during the folding reaction. However, regulating or analyzing the structures of folding intermediates of peptides and proteins continues to be a difficult problem. Recently, the development of several techniques in peptide chemistry and biotechnology has resulted in the availability of some powerful tools for studying protein folding in the context of the structural analysis of native, mutant proteins, and folding intermediates. In this review, recent developments in the field of disulfide-coupled peptide and protein folding are discussed, from the viewpoint of chemical and biotechnological methods, such as analytical methods for the detection of disulfide pairings, chemical methods for disulfide bond formation between the defined Cys residues, and applications of diselenide bonds for the regulation of disulfide-coupled peptide and protein folding.

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Role of disulfide bonds in folding and secretion of human lysozyme in saccharomycescerevisiae

Biochemical and Biophysical Research Communications ◽

10.1016/s0006-291x(88)80377-2 ◽

1988 ◽

Vol 152 (3) ◽

pp. 962-967 ◽

Cited By ~ 45

Author(s):

Yoshio Taniyama ◽

Yoshio Yamamoto ◽

Masafumi Nakao ◽

Masakazu Kikuchi ◽

Morio Ikehara

Keyword(s):

Disulfide Bonds ◽

Human Lysozyme

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Role of the Ndc1 interaction network in yeast nuclear pore complex assembly and maintenance

The Journal of Cell Biology ◽

10.1083/jcb.200810030 ◽

2009 ◽

Vol 185 (3) ◽

pp. 475-491 ◽

Cited By ~ 97

Author(s):

Evgeny Onischenko ◽

Leslie H. Stanton ◽

Alexis S. Madrid ◽

Thomas Kieselbach ◽

Karsten Weis

Keyword(s):

Nuclear Pore Complex ◽

Structural Integrity ◽

Fluorescent Protein ◽

Interaction Network ◽

Nucleocytoplasmic Transport ◽

Nuclear Pore ◽

Binding Partners ◽

Interaction Partners ◽

Redundant Functions

The nuclear pore complex (NPC) mediates all nucleocytoplasmic transport, yet its structure and biogenesis remain poorly understood. In this study, we have functionally characterized interaction partners of the yeast transmembrane nucleoporin Ndc1. Ndc1 forms a distinct complex with the transmembrane proteins Pom152 and Pom34 and two alternative complexes with the soluble nucleoporins Nup53 and Nup59, which in turn bind to Nup170 and Nup157. The transmembrane and soluble Ndc1-binding partners have redundant functions at the NPC, and disruption of both groups of interactions causes defects in Ndc1 targeting and in NPC structure accompanied by significant pore dilation. Using photoconvertible fluorescent protein fusions, we further show that the depletion of Pom34 in cells that lack NUP53 and NUP59 blocks new NPC assembly and leads to the reversible accumulation of newly made nucleoporins in cytoplasmic foci. Therefore, Ndc1 together with its interaction partners are collectively essential for the biosynthesis and structural integrity of yeast NPCs.

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Neural induction and the structure of the target cell surface

Development ◽

10.1242/dev.70.1.171 ◽

1982 ◽

Vol 70 (1) ◽

pp. 171-187

Author(s):

A. M. Duprat ◽

L. Gualandris ◽

P. Rouge

Keyword(s):

Cell Surface ◽

Structural Integrity ◽

Neural Induction ◽

Active Role ◽

Target Cells ◽

Similar Treatment ◽

Structural Modifications ◽

Pleurodeles Waltl

Lectins (SBA and PSA) were used to provoke crowding and structural modifications of the presumptive ectoderm cell surface in order to investigate the role of the membrane organization of the competent target cells in neural induction. Are specific characteristics of the cell surface essential for this phenomenon to occur? From amphibian gastrulae, it is possible to obtain neural induction in vitro by association of presumptive ectoderm (target cells) with chordamesoderm (inductor tissue): 4 h of contact is sufficient in Pleurodeles waltl for transmission of the inductive signal. Very quickly, the treatment of the normal ectoderm by lectins (SBA-FITC or PSA-FITC) provoked surface modifications. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm did not result in any neural induction. Lectin-treatment (50 µg ml1−, 30 min) of presumptive ectoderm previous to its association with the natural inductor for 4 h, disturbed the phenomenon: no induction. Similar treatment followed by association with the inductor for 24 h: induction. Treatment of SBA or PSA with their respective hapten inhibitors prior to addition to ectodermal cells completely blocked the suppressive effects on induction. The structural integrity of the membrane of competent target cells is necessary for neural induction to occur. The cell membrane could thus play, directly or indirectly, an active role in the specificity of this process

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Iron Requirement for Mn(II) Oxidation by Leptothrix discophora SS-1

Applied and Environmental Microbiology ◽

10.1128/aem.02291-08 ◽

2008 ◽

Vol 75 (5) ◽

pp. 1229-1235 ◽

Cited By ~ 28

Author(s):

Iman A. El Gheriany ◽

Daniela Bocioaga ◽

Anthony G. Hay ◽

William C. Ghiorse ◽

Michael L. Shuler ◽

...

Keyword(s):

Complex Formation ◽

Temporal Variations ◽

Iron Limitation ◽

Gene Transcript ◽

Cellular Functions ◽

Transcript Levels ◽

Leptothrix Discophora ◽

Geochemical Cycling ◽

Iron Requirement

ABSTRACT A common form of biocatalysis of Mn(II) oxidation results in the formation of biogenic Mn(III, IV) oxides and is a key reaction in the geochemical cycling of Mn. In this study, we grew the model Mn(II)-oxidizing bacterium Leptothrix discophora SS-1 in media with limited iron (0.1 μM iron/5.8 mM pyruvate) and sufficient iron (0.2 μM iron/5.8 mM pyruvate). The influence of iron on the rate of extracellular Mn(II) oxidation was evaluated. Cultures in which cell growth was limited by iron exhibited reduced abilities to oxidize Mn(II) compared to cultures in medium with sufficient iron. While the extracellular Mn(II)-oxidizing factor (MOF) is thought to be a putative multicopper oxidase, Mn(II) oxidation in the presence of zero added Cu(II) was detected and the decrease in the observed Mn(II) oxidation rate in iron-limited cultures was not relieved when the medium was supplemented with Cu(II). The decline of Mn(II) oxidation under iron-limited conditions was not accompanied by siderophore production and is unlikely to be an artifact of siderophore complex formation with Mn(III). The temporal variations in mofA gene transcript levels under conditions of limited and abundant iron were similar, indicating that iron limitation did not interfere with the transcription of the mofA gene. Our quantitative PCR results provide a step forward in understanding the regulation of Mn(II) oxidation. The mechanistic role of iron in Mn(II) oxidation is uncertain; the data are consistent with a direct requirement for iron as a component of the MOF or an indirect effect of iron resulting from the limitation of one of many cellular functions requiring iron.

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A review of fungal influenced corrosion of metals

Zastita materijala ◽

10.5937/zasmat2104333o ◽

2021 ◽

Vol 62 (4) ◽

pp. 333-339

Author(s):

Imo Okorie ◽

Romanus Nwokorie

Keyword(s):

Growth Pattern ◽

Metal Surfaces ◽

Structural Integrity ◽

Great Influence ◽

Fungal Growth ◽

Corrosive Media ◽

Electrochemical Processes ◽

Single Mechanism ◽

Growth Of Fungi

The growth of fungi on the surface of metals has great influence on their structural integrity and failure. Their growth on metal surfaces is determined by their secreted metabolites which enable them to adapt to new environmental and nourishment conditions. Although information on the capacity of fungi to adapt to metal surfaces is scarce, most fungi growing on metal surfaces alter the composition of the metals involving it in the process of functional growth and metabolism. Changes in the composition and colour of the metals are some of the evidences confirming that fungus has penetrated the metal surfaces and use it to satisfy its nutritional need with resultant corrosion. In this work we tried to explain different mechanisms of fungal influenced corrosion from different perspectives ranging from the role of biofilms, corrosive media generation by fungal metabolism processes to electrochemical processes generated by fungal growth on metal surfaces. Finally, no single mechanism can conclusively explain all forms of fungal influenced corrosion because every mechanism is unique and applies to individual fungus, its metabolic biproducts or the growth pattern.

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A study of organo-hectorite clay crystallization

Clay Minerals ◽

10.1180/claymin.1997.032.1.05 ◽

1997 ◽

Vol 32 (1) ◽

pp. 29-40 ◽

Cited By ~ 36

Author(s):

K. A. Carrado ◽

P. Thiyagarajan ◽

K. Song

Keyword(s):

Room Temperature ◽

Structural Integrity ◽

Effect Of Temperature ◽

Clay Layer ◽

Layer Formation ◽

Surface Areas ◽

Line Shape Analysis ◽

Long Time ◽

Organometallic Molecules

AbstractA method has been developed to synthesize organo-hectorite clays directly from a Mg-silicate gel containing organic or organometallic molecules that are expected to be incorporated within the interlayer space. Complete crystallization occurs upon aqueous reflux for 48 h. The progress of clay layer formation was monitored by X-ray powder diffraction (XRD), differential thermal gravimetry (DTG), and infrared (IR) spectroscopy. Evidence of clay XRD peaks occurs after just 4 h of hydrothermal treatment, and Mg(OH)2 is no longer observable after 14 h. Observable changes in DTG and IR occur at about this time as well. Warren line-shape analysis of the 110 reflection indicates that when growth is complete the clay lamellae are on average ∼50% and 25% of the size of natural hectorites and montmorillonites, respectively. The N2 BET surface areas for all materials are also compared. Small angle neutron scattering shows that addition of tetraethyl ammonium (TEA) ions does not alter the structural integrity over that of the purely inorganic form of Li-hectorite, but that use of a cationic polymer does significantly alter the microstructure. The effect of temperature is critical, for at room temperature only the layered Mg hydroxide mineral brucite crystallizes unless very long time scales are used. The crystallizations carried out at room temperature show that clay will form after about 3 months, but that the presence of organics (at least TEA) acts to hinder this process greatly. The role of the organic molecules on silicate clay layer formation is compared with the role of organics in zeolite synthesis.

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